Open Electronics

The Y2K wrist sequencer is a musical device worn like a watch. It composes music by selecting sounds for each step and playing them back in sequence. The transparent 3D-printed case and snap-band bracelet make it a fashion accessory as well as an instrument. The project comes from 3DSage, who chose simple components and a retro aesthetic that hits the mark.

The heart of the system is an ESP32, which handles the sequencer logic and sound generation. A rotary encoder enables the standard sequencer workflows: scroll through steps, select a sound, and store it in the desired position. The LCD display shows the state of the composition, while the speaker plays the tones. There is also a headphone jack for private listening.

How the Y2K wrist sequencer works

The operation is simple and straightforward. For each step, the user selects a sound to store in that position, such as a square-wave A note at 440Hz. The rotary encoder allows navigating between options and confirming choices. The touch pins, made from brass bar, cover an octave and make the device work more like a Stylophone synthesizer. The sequential playback lets you hear all stored sounds, creating a rhythmic melody.

The ESP32 can produce more complex waveforms, but the basic square-wave tones chosen for the default sounds fit the aesthetic perfectly. This approach keeps the project simple and true to the Y2K spirit. Additionally, the choice of a rechargeable AA battery makes the device portable and easy to recharge. The transparent PETG case adds a visual touch that recalls late-1990s gadgets.

Why this project is interesting

It is a simple and stylish way to make music, with a retro Y2K aesthetic that hits the nostalgia sweet spot. You don’t need to be a synthesis expert to use it: the controls are immediate and the visual feedback on the display guides you step by step. Moreover, the project is fully reproducible with easily available components. To get started you need only a few parts: an ESP32 board with 32 GPIOs, a 12mm rotary encoder with knob, and a 0.25-watt speaker. The transparent case is printed in PETG, the same material chosen by 3DSage.

The choice of the rotary encoder is spot-on for physical interaction: rotation and pressure give tactile feedback that recalls old synthesizers. The brass pins, on the other hand, add a live performance element. The result is a device that can be used both for planned composition and for improvisation. Thanks to the transparent case, you can see the internal circuit, a detail makers will appreciate.

How to remake the project

To build the Y2K wrist sequencer you need few components. Besides the ESP32, you need a rotary encoder, an LCD display, a speaker, and a rechargeable AA battery. The touch pins are made from a brass bar, while the case is 3D-printed in transparent PETG. The snap-band bracelet completes the wearable design.

• ESP32 for logic and sound generation
• Rotary encoder for navigation and selection
• LCD display for visual feedback
• Speaker and headphone jack for audio output
• Rechargeable AA battery for power
• Brass bar for touch pins
• Transparent PETG for the 3D-printed case

Assembly requires some soldering and 3D printing of the case. Once assembled, the device is worn on the wrist and you can start composing. The sequential playback makes everything immediate: press the pins, select sounds, and listen to the result. The 3DSage video shows the step-by-step build, from printing the case to mounting the brass pins.

For power, a rechargeable AA battery is sufficient thanks to the ESP32’s low consumption. If you want to experiment with other boards in the ESP32 family, you can easily adapt the code. The project is a great starting point for anyone wanting to explore music synthesis with open-source hardware. Finally, the transparent case is customizable: you can change the color or add decorations.

Source: https://youtu.be/RrWw1gm3UEo?si=SbXtYVeqWxJHxh0B

Related products

• 12mm rotary encoder with knob

The post Y2K Wrist Sequencer: Retro Music with ESP32 appeared first on Open Electronics.

The Y2K wrist sequencer is a musical device worn like a watch. It composes music by selecting sounds for each step and playing them back in sequence. The transparent 3D-printed case and snap-band bracelet make it a fashion accessory as well as an instrument. The project comes from 3DSage, who chose simple components and a retro aesthetic that hits the mark.

The heart of the system is an ESP32, which handles the sequencer logic and sound generation. A rotary encoder enables the standard sequencer workflows: scroll through steps, select a sound, and store it in the desired position. The LCD display shows the state of the composition, while the speaker plays the tones. There is also a headphone jack for private listening.

How the Y2K wrist sequencer works

The operation is simple and straightforward. For each step, the user selects a sound to store in that position, such as a square-wave A note at 440Hz. The rotary encoder allows navigating between options and confirming choices. The touch pins, made from brass bar, cover an octave and make the device work more like a Stylophone synthesizer. The sequential playback lets you hear all stored sounds, creating a rhythmic melody.

The ESP32 can produce more complex waveforms, but the basic square-wave tones chosen for the default sounds fit the aesthetic perfectly. This approach keeps the project simple and true to the Y2K spirit. Additionally, the choice of a rechargeable AA battery makes the device portable and easy to recharge. The transparent PETG case adds a visual touch that recalls late-1990s gadgets.

Why this project is interesting

It is a simple and stylish way to make music, with a retro Y2K aesthetic that hits the nostalgia sweet spot. You don’t need to be a synthesis expert to use it: the controls are immediate and the visual feedback on the display guides you step by step. Moreover, the project is fully reproducible with easily available components. To get started you need only a few parts: an ESP32 board with 32 GPIOs, a 12mm rotary encoder with knob, and a 0.25-watt speaker. The transparent case is printed in PETG, the same material chosen by 3DSage.

The choice of the rotary encoder is spot-on for physical interaction: rotation and pressure give tactile feedback that recalls old synthesizers. The brass pins, on the other hand, add a live performance element. The result is a device that can be used both for planned composition and for improvisation. Thanks to the transparent case, you can see the internal circuit, a detail makers will appreciate.

How to remake the project

To build the Y2K wrist sequencer you need few components. Besides the ESP32, you need a rotary encoder, an LCD display, a speaker, and a rechargeable AA battery. The touch pins are made from a brass bar, while the case is 3D-printed in transparent PETG. The snap-band bracelet completes the wearable design.

• ESP32 for logic and sound generation
• Rotary encoder for navigation and selection
• LCD display for visual feedback
• Speaker and headphone jack for audio output
• Rechargeable AA battery for power
• Brass bar for touch pins
• Transparent PETG for the 3D-printed case

Assembly requires some soldering and 3D printing of the case. Once assembled, the device is worn on the wrist and you can start composing. The sequential playback makes everything immediate: press the pins, select sounds, and listen to the result. The 3DSage video shows the step-by-step build, from printing the case to mounting the brass pins.

For power, a rechargeable AA battery is sufficient thanks to the ESP32’s low consumption. If you want to experiment with other boards in the ESP32 family, you can easily adapt the code. The project is a great starting point for anyone wanting to explore music synthesis with open-source hardware. Finally, the transparent case is customizable: you can change the color or add decorations.

Source: https://youtu.be/RrWw1gm3UEo?si=SbXtYVeqWxJHxh0B

Related products

• 12mm rotary encoder with knob

The post Y2K Wrist Sequencer: Retro Music with ESP32 appeared first on Open Electronics.

Building a motorized welding turntable solves a common problem: welding around circular or cylindrical objects without walking around the workpiece. Greenhill Forge’s project creates a large motorized lazy Susan with adjustable speed and a modest budget. The table rotates the piece under the torch, so the welder stays still and both hands are free to guide the arc.

The heart of the system is a stepper motor mounted under the table surface. Rotation passes through a gear reducer and a standard spider coupling, which transmits motion to the top plate. The reducer increases torque and lowers speed, so the table moves smoothly even with heavy parts. Everything is controlled by an Arduino UNO Rev3 board, which drives the motor and reads user commands.

Speed control and user interface

The user adjusts rotation speed with a rotary encoder. The knob is comfortable to use even with welding gloves. A small OLED screen shows the set speed, so control is immediate and precise. The firmware on the Arduino UNO reads the encoder, updates the display, and drives the stepper motor with the correct pulse frequency.

For those who want to replicate the project, choosing components is straightforward. A Uno R3 with ATmega328 is the same board used in the original project. A NEMA 17 stepper motor rated at 1.2 A has the right torque for a table of this size, which rotates through a reducer anyway. A 12 mm rotary encoder with knob connects directly to digital pins and can be turned even with welding gloves. Finally, a 128×64 OLED display shows parameters clearly.

• Stepper motor with gear reducer for torque
• Spider coupling to connect shaft and table
• Lazy Susan bearing for rotating support
• Rotary encoder for adjustment
• OLED display for visual feedback

Grounding through the shaft

An important detail is grounding management. In welding, current must return to the generator through the workpiece. If the turntable is not grounded, current passes through the lazy Susan bearings, causing arcs that damage them quickly. Greenhill Forge solves the problem with a ground strap that runs through the motor shaft.

The strap maintains conductivity between the table surface and the workpiece. This way, welding current has a dedicated path and the bearings stay protected. The strap is a wear item, but with normal use it should last a long time. Also, replacement cost is minimal, so maintenance stays economical.

The project is documented in a Greenhill Forge video, which follows the entire process: cutting and welding the frame, mounting the motor under the table, and grounding. At the end, the table is shown in action during a real weld, with speed adjusted on the fly.

Why build a turntable

This project appeals to both beginners and experienced welders. Construction is simple and requires few tools. Moreover, electronic control with Arduino UNO opens the door to future modifications, such as programmed rotation or foot pedal control. The modest cost makes the project accessible to many makers.

The welding turntable is an example of how a stepper motor, an encoder, and an OLED display can turn a simple support into a professional tool. Well-designed grounding protects components and ensures quality welds. Finally, adjustable speed lets you adapt rotation to any type of work.

Source: https://youtu.be/WQSzLMcc9zQ?si=DB7dDrRwHsfXU1OI

Related products

• 12mm rotary encoder with knob

The post Motorized welding turntable with Arduino UNO appeared first on Open Electronics.

Building a motorized welding turntable solves a common problem: welding around circular or cylindrical objects without walking around the workpiece. Greenhill Forge’s project creates a large motorized lazy Susan with adjustable speed and a modest budget. The table rotates the piece under the torch, so the welder stays still and both hands are free to guide the arc.

The heart of the system is a stepper motor mounted under the table surface. Rotation passes through a gear reducer and a standard spider coupling, which transmits motion to the top plate. The reducer increases torque and lowers speed, so the table moves smoothly even with heavy parts. Everything is controlled by an Arduino UNO Rev3 board, which drives the motor and reads user commands.

Speed control and user interface

The user adjusts rotation speed with a rotary encoder. The knob is comfortable to use even with welding gloves. A small OLED screen shows the set speed, so control is immediate and precise. The firmware on the Arduino UNO reads the encoder, updates the display, and drives the stepper motor with the correct pulse frequency.

For those who want to replicate the project, choosing components is straightforward. A Uno R3 with ATmega328 is the same board used in the original project. A NEMA 17 stepper motor rated at 1.2 A has the right torque for a table of this size, which rotates through a reducer anyway. A 12 mm rotary encoder with knob connects directly to digital pins and can be turned even with welding gloves. Finally, a 128×64 OLED display shows parameters clearly.

• Stepper motor with gear reducer for torque
• Spider coupling to connect shaft and table
• Lazy Susan bearing for rotating support
• Rotary encoder for adjustment
• OLED display for visual feedback

Grounding through the shaft

An important detail is grounding management. In welding, current must return to the generator through the workpiece. If the turntable is not grounded, current passes through the lazy Susan bearings, causing arcs that damage them quickly. Greenhill Forge solves the problem with a ground strap that runs through the motor shaft.

The strap maintains conductivity between the table surface and the workpiece. This way, welding current has a dedicated path and the bearings stay protected. The strap is a wear item, but with normal use it should last a long time. Also, replacement cost is minimal, so maintenance stays economical.

The project is documented in a Greenhill Forge video, which follows the entire process: cutting and welding the frame, mounting the motor under the table, and grounding. At the end, the table is shown in action during a real weld, with speed adjusted on the fly.

Why build a turntable

This project appeals to both beginners and experienced welders. Construction is simple and requires few tools. Moreover, electronic control with Arduino UNO opens the door to future modifications, such as programmed rotation or foot pedal control. The modest cost makes the project accessible to many makers.

The welding turntable is an example of how a stepper motor, an encoder, and an OLED display can turn a simple support into a professional tool. Well-designed grounding protects components and ensures quality welds. Finally, adjustable speed lets you adapt rotation to any type of work.

Source: https://youtu.be/WQSzLMcc9zQ?si=DB7dDrRwHsfXU1OI

Related products

• 12mm rotary encoder with knob

The post Motorized welding turntable with Arduino UNO appeared first on Open Electronics.

Let’s get to know and learn how to use a board for RF tag identification, easily paired with Arduino.

We have covered radio-frequency identification, better known as RFID, several times before; for example, in issue no. 254 we dedicated an in-depth look at it with a thorough theoretical introduction and some usage examples based on the RFID PN522 module, accompanied by the ever-present Arduino board. In this article, we pick up the discussion again by experimenting with another module, the RFID-RC522, based on the MFRC522 chip produced by NXP (the datasheet is available at the web link https://www.nxp.com/docs/en/data-sheet/MFRC522.pdf).

The RFID-RC522 module

The MFRC522 is a highly integrated RFID reader/writer for contactless communication at 13.56 MHz, supporting the ISO/IEC14443A/MIFARE and NTAG standards.

The transmitter inside the MFRC522 can drive an antenna designed to communicate with cards and transponders without additional active circuits. The internal receiver can efficiently demodulate and decode signals from cards and transponders compatible with the standards listed above.

The MFRC522 supports the MF1xxS20, MF1xxS70, and MF1xxS50 models. It also supports contactless communication with MIFARE transfer rates up to 848 kB (kiloBaud) in bidirectional mode.

The MFRC522 is compatible with all variants of the MIFARE identification protocols MIFARE Mini, MIFARE 1K, MIFARE 4K, MIFARE Ultralight, MIFARE DESFire EV1, and MIFARE Plus RF, grouped under the generic term MIFARE.

Below we summarize the main technical features of the module:

• analog circuit to demodulate and decode responses;
• buffered drivers for connecting an antenna with a reduced number of external components;
• supports ISO/IEC 14443 A/MIFARE and NTAG;
• typical operating distance in read/write mode up to 50 mm depending on antenna size and tuning;
• supports MF1xxS20, MF1xxS70, and MF1xxS50 encryption in read/write mode;
• supports ISO/IEC 14443 with high transfer rate communication up to 848 kbaud;
• supports MFIN/MFOUT;
• additional internal power supply to the smart card IC connected via MFIN/MFOUT;
• supported host interfaces: SPI up to 10 Mbit/s, I²C-Bus up to 400 kBd in Fast mode, up to 3400 kBd in High-speed mode, serial UART RS232 up to 1,228.8 kB/s, with voltage levels depending on the pin supply voltage;
• the FIFO buffer manages sending and receiving at 64 bytes;
• flexible interrupt modes;
• hard reset with low-power function;
• software power-down;
• programmable timer;
• supply voltage from 2.5 to 3.3 V;
• programmable I/O pins.

The RFID-RC522 module is detailed in Fig. 1, where you can see all the available connections.

Connecting to Arduino

Since all current libraries for using the module with Arduino reuse the SPI connection, we will focus only on that; Fig. 2 illustrates the connection to make for the subsequent tests with Arduino UNO.

In Table 1 we describe the connections analytically with their signals: on the left are those of the Arduino UNO and on the right the contacts of the RFID-RC522 module with the corresponding wire colors in the diagram in Fig. 2. The IRQ pin of the RFID module should be left unconnected because we do not manage it in this project and do not need it.

Of course, you must be very careful, because swapping just two wires will cause the module to fail; another important thing is power: the module requires 3.3 V, and the corresponding pin on Arduino is right next to the 5 V one; a moment of distraction would almost certainly damage the module.

The board (the RFID module used in the project) comes with two 8-pin strip headers (one straight and one at 90°) to solder as you prefer into the appropriate signal holes, an RFID Tag Card, and an RFID keychain Tag for initial testing.

Libraries for RC522

Using this module is made easier by the availability of specific libraries, of which we have selected two: the one from Velleman and the one written by Miguel Balboa.

Velleman: it is a minimal library consisting of only two files (RFID.h and RFID.cpp). Once downloaded from the link: https://www.velleman.eu/downloads/29/vma405_library.zip, you need to include it by opening a new sketch with an updated version of the IDE (in our case 1.8.12). Run the command Sketch – Include Library – Add .ZIP Library… and select the .zip file (Fig. 3), then close the IDE; it will be available when you reopen it.

Miguel Balboa: this library, much more powerful and articulated, is recommended by the official Arduino website; it is constantly updated, so it is always best to go to the link https://www.arduino.cc/reference/en/libraries/mfrc522/ or directly to the GitHub https://github.com/miguelbalboa/rfid; at the time of writing, the latest version is 1.4.8.

Its inclusion in the IDE is done in the same way as seen before. This library is quite demanding and requires considerable skills in RFID and programming to exploit it, so we only point it out to more experienced readers, while for the test we will see later we will use the one distributed by Velleman.

Functionality test

Let’s start with a test to verify the connections and the correct installation of the vma405 library. We have prepared a sketch named “RFID_TAG_CODE”; open it in the IDE and upload it to the Arduino UNO, then open the Serial Monitor, which will show the message “Avvicina un Tag al Modulo” (Bring a Tag close to the Module); at this point, bring the Tag close to the part of the module where the radio wave symbols are silkscreened (Fig. 4).

Keep in mind that the module should always be kept away from devices that can generate electric or electromagnetic fields, otherwise it might not work correctly.

The moment the Tag is recognized, the module reads its UID (unique identification code) and displays it on the Serial Monitor, both in decimal and hexadecimal format; in Fig. 5 we can observe the successive reading of two Tags.

If after the first identification you bring the same Tag close again, nothing will happen because we have not included an alternative action in the sketch; bringing another Tag close instead will give its UID in both formats.

When this test succeeds, you need to decide which Tag will be the “System Administrator” of the circuit we have prepared for experimenting with this module and note the five decimal numbers that make up its UID. For our example, we will use the first group visible in the figure (197, 5, 190, 35, 93).

Access control project

With the help of a breadboard and very few other components, let’s now build a circuit to simulate an access control system using RFID technology with our RC522 module.

The sketch we have prepared can be downloaded and is called Access_Control.rar; it consists of two tabs, and the folder obtained from decompressing the file must be placed in the sketch folder of your IDE; the vma405_library must have been installed beforehand.

The idea is a hypothetical access control system, where the acceptance of a Tag is indicated by the alternating on/off of a blue LED, while rejection is represented by a red LED turning on for about 3 seconds.

Authorized Tags are pre-stored in the EEPROM of the Arduino microcontroller; our sketch supports up to three, but they can be increased up to the availability of the EEPROM. Storage only happens with prior authorization from the “System Administrator,” who has an RFID CARD Tag whose UID must be manually entered in the sketch and which, once read by the module, allows other Tags to be brought close to accredit them and store them in the EEPROM.

From this point on, when you bring an authorized tag near the module, the blue LED will turn on or off with each pass, toggling its state. The red LED, on the other hand, will light up for three seconds when someone tries to gain access with an unregistered tag, effectively denying authorization, and then it will turn off.

Before uploading the sketch to the Arduino, you need to open it and assign the corresponding decimal values of the chosen tag’s UID to the five variables dec_code0 through dec_code4 (Fig. 6), replacing the pre-stored values you will find there.

At this point you can upload the sketch to the Arduino and then disconnect the USB cable to remove power. Next, move on to building the practical layout shown in Fig. 7, which explains how to connect all the required components.

Required materials

The materials needed to build the project are:

• RFID-RC522 module
• Arduino UNO
• Breadboard with side power rails (red and black, or red and blue)
• 6×6 mm push button
• Red LED
• Blue LED (or another color of your choice)
• 2 resistors of 220 Ohm
• 1 resistor of 10 kOhm
• 5 M-M jumper wires
• 7 M-F jumper wires
• 1 jumper bridge, 3-pin
• 1 jumper bridge, 5-pin
• 1 jumper bridge, 19-pin
• 4 tags, one of which marked as administrator

Note that regarding jumper wires and bridges, we provided the list to replicate our exact practical layout; of course you can make any variation, as long as you correctly make the proposed connections, otherwise the circuit will not work. Above all, be extremely careful not to reverse the power supply (3.3V and GND), otherwise you risk burning the module!

A special note about the breadboard: during our tests we came across a model with the power rails interrupted in the middle section. This was actually clearly indicated by the break in the red and blue silkscreen lines, but since it is unusual, we initially did not notice it. As a result, the RC522 module’s LED still turned on (due to current carried by the signals), but tag reading did not work. We therefore had to add two jumper wires to connect the two rails along their entire length (Fig. 8), i.e., to bridge them.

How the access control works

Once the circuit is complete on the breadboard and the connections are checked, to begin simply reconnect the USB cable from the PC to the Arduino UNO board. You will see the RC522 module’s red LED light up (but as explained earlier, this does not indicate correct power supply), while the two red and blue LEDs on the breadboard remain off.

Now open the Serial Monitor of the Arduino IDE, and the message “Controllo accessi attivo” will appear. The first operation to perform is to bring the Administrator tag near the module. If everything is in order, the two LEDs will blink simultaneously three times and remain on; the Serial Monitor will also show the message visible in Fig. 9, indicating that Administrator mode is active.

If at first power-up a number other than 0 appears (usually it will be 255), you need to reset the EEPROM. Simply press the push button mounted on the breadboard to achieve the desired result (Fig. 10).

After the reset, you will exit Administrator mode and the LEDs will turn off. You must pass the Administrator tag again to re-enter, then simply bring the tag you want to authorize near the module to store its UID (Fig. 11).

This operation can be performed for a maximum of three tags; after that, no more can be stored unless you modify the sketch accordingly.

Daily use of the system

At this point we can observe the circuit’s behavior depending on the type of tag we bring near the RFID reader; there are two possibilities.

Unregistered tag: the red LED turns on for about three seconds, then turns off; authorization is denied.

Registered tag: if the blue LED is off, it turns on, indicating that authorization has been granted; the LED stays on until you pass the same tag or another registered tag, at which point it turns off.

One last curiosity: if you lack other tags to simulate unauthorized access, you can use your own smartphone. If you have a phone with an NFC chip running Android 5.0 or later, simply enable NFC in the settings and then use the smartphone as if it were a tag.

In fact, when you bring it near the module with the chip side facing it, it will be recognized as a tag, but with a peculiarity that prevents its use as an authorized tag: with each new read, the UID turns out to be different from the previous read. This is easily verifiable with the “RFID_TAG_CODE” sketch. So even if you store the chip as authorized, it will not be recognized on subsequent reads.

In some rare cases, the smartphone may need a specific app to function as a tag. Simply download “NFC Tools” from the Play Store and leave it active, without doing anything else.

Conclusions

We end this article with a suggestion: as you can easily imagine, this project can be expanded by adding, for example, a relay driven by the same pin as the blue LED, which would allow you to activate an actuator such as an electric lock. The only limits are those of your imagination.

Naturally, the greater the complexity of the expansion, the more variations and implementations you will need to make to the sketch, but it will all be a useful programming exercise that will increase your skills and give you great satisfaction.

The post RFID with RC522: Radio-Frequency Identification with Arduino appeared first on Open Electronics.

Let’s get to know and learn how to use a board for RF tag identification, easily paired with Arduino.

We have covered radio-frequency identification, better known as RFID, several times before; for example, in issue no. 254 we dedicated an in-depth look at it with a thorough theoretical introduction and some usage examples based on the RFID PN522 module, accompanied by the ever-present Arduino board. In this article, we pick up the discussion again by experimenting with another module, the RFID-RC522, based on the MFRC522 chip produced by NXP (the datasheet is available at the web link https://www.nxp.com/docs/en/data-sheet/MFRC522.pdf).

The RFID-RC522 module

The MFRC522 is a highly integrated RFID reader/writer for contactless communication at 13.56 MHz, supporting the ISO/IEC14443A/MIFARE and NTAG standards.

The transmitter inside the MFRC522 can drive an antenna designed to communicate with cards and transponders without additional active circuits. The internal receiver can efficiently demodulate and decode signals from cards and transponders compatible with the standards listed above.

The MFRC522 supports the MF1xxS20, MF1xxS70, and MF1xxS50 models. It also supports contactless communication with MIFARE transfer rates up to 848 kB (kiloBaud) in bidirectional mode.

The MFRC522 is compatible with all variants of the MIFARE identification protocols MIFARE Mini, MIFARE 1K, MIFARE 4K, MIFARE Ultralight, MIFARE DESFire EV1, and MIFARE Plus RF, grouped under the generic term MIFARE.

Below we summarize the main technical features of the module:

• analog circuit to demodulate and decode responses;
• buffered drivers for connecting an antenna with a reduced number of external components;
• supports ISO/IEC 14443 A/MIFARE and NTAG;
• typical operating distance in read/write mode up to 50 mm depending on antenna size and tuning;
• supports MF1xxS20, MF1xxS70, and MF1xxS50 encryption in read/write mode;
• supports ISO/IEC 14443 with high transfer rate communication up to 848 kbaud;
• supports MFIN/MFOUT;
• additional internal power supply to the smart card IC connected via MFIN/MFOUT;
• supported host interfaces: SPI up to 10 Mbit/s, I²C-Bus up to 400 kBd in Fast mode, up to 3400 kBd in High-speed mode, serial UART RS232 up to 1,228.8 kB/s, with voltage levels depending on the pin supply voltage;
• the FIFO buffer manages sending and receiving at 64 bytes;
• flexible interrupt modes;
• hard reset with low-power function;
• software power-down;
• programmable timer;
• supply voltage from 2.5 to 3.3 V;
• programmable I/O pins.

The RFID-RC522 module is detailed in Fig. 1, where you can see all the available connections.

Connecting to Arduino

Since all current libraries for using the module with Arduino reuse the SPI connection, we will focus only on that; Fig. 2 illustrates the connection to make for the subsequent tests with Arduino UNO.

In Table 1 we describe the connections analytically with their signals: on the left are those of the Arduino UNO and on the right the contacts of the RFID-RC522 module with the corresponding wire colors in the diagram in Fig. 2. The IRQ pin of the RFID module should be left unconnected because we do not manage it in this project and do not need it.

Of course, you must be very careful, because swapping just two wires will cause the module to fail; another important thing is power: the module requires 3.3 V, and the corresponding pin on Arduino is right next to the 5 V one; a moment of distraction would almost certainly damage the module.

The board (the RFID module used in the project) comes with two 8-pin strip headers (one straight and one at 90°) to solder as you prefer into the appropriate signal holes, an RFID Tag Card, and an RFID keychain Tag for initial testing.

Libraries for RC522

Using this module is made easier by the availability of specific libraries, of which we have selected two: the one from Velleman and the one written by Miguel Balboa.

Velleman: it is a minimal library consisting of only two files (RFID.h and RFID.cpp). Once downloaded from the link: https://www.velleman.eu/downloads/29/vma405_library.zip, you need to include it by opening a new sketch with an updated version of the IDE (in our case 1.8.12). Run the command Sketch – Include Library – Add .ZIP Library… and select the .zip file (Fig. 3), then close the IDE; it will be available when you reopen it.

Miguel Balboa: this library, much more powerful and articulated, is recommended by the official Arduino website; it is constantly updated, so it is always best to go to the link https://www.arduino.cc/reference/en/libraries/mfrc522/ or directly to the GitHub https://github.com/miguelbalboa/rfid; at the time of writing, the latest version is 1.4.8.

Its inclusion in the IDE is done in the same way as seen before. This library is quite demanding and requires considerable skills in RFID and programming to exploit it, so we only point it out to more experienced readers, while for the test we will see later we will use the one distributed by Velleman.

Functionality test

Let’s start with a test to verify the connections and the correct installation of the vma405 library. We have prepared a sketch named “RFID_TAG_CODE”; open it in the IDE and upload it to the Arduino UNO, then open the Serial Monitor, which will show the message “Avvicina un Tag al Modulo” (Bring a Tag close to the Module); at this point, bring the Tag close to the part of the module where the radio wave symbols are silkscreened (Fig. 4).

Keep in mind that the module should always be kept away from devices that can generate electric or electromagnetic fields, otherwise it might not work correctly.

The moment the Tag is recognized, the module reads its UID (unique identification code) and displays it on the Serial Monitor, both in decimal and hexadecimal format; in Fig. 5 we can observe the successive reading of two Tags.

If after the first identification you bring the same Tag close again, nothing will happen because we have not included an alternative action in the sketch; bringing another Tag close instead will give its UID in both formats.

When this test succeeds, you need to decide which Tag will be the “System Administrator” of the circuit we have prepared for experimenting with this module and note the five decimal numbers that make up its UID. For our example, we will use the first group visible in the figure (197, 5, 190, 35, 93).

Access control project

With the help of a breadboard and very few other components, let’s now build a circuit to simulate an access control system using RFID technology with our RC522 module.

The sketch we have prepared can be downloaded and is called Access_Control.rar; it consists of two tabs, and the folder obtained from decompressing the file must be placed in the sketch folder of your IDE; the vma405_library must have been installed beforehand.

The idea is a hypothetical access control system, where the acceptance of a Tag is indicated by the alternating on/off of a blue LED, while rejection is represented by a red LED turning on for about 3 seconds.

Authorized Tags are pre-stored in the EEPROM of the Arduino microcontroller; our sketch supports up to three, but they can be increased up to the availability of the EEPROM. Storage only happens with prior authorization from the “System Administrator,” who has an RFID CARD Tag whose UID must be manually entered in the sketch and which, once read by the module, allows other Tags to be brought close to accredit them and store them in the EEPROM.

From this point on, when you bring an authorized tag near the module, the blue LED will turn on or off with each pass, toggling its state. The red LED, on the other hand, will light up for three seconds when someone tries to gain access with an unregistered tag, effectively denying authorization, and then it will turn off.

Before uploading the sketch to the Arduino, you need to open it and assign the corresponding decimal values of the chosen tag’s UID to the five variables dec_code0 through dec_code4 (Fig. 6), replacing the pre-stored values you will find there.

At this point you can upload the sketch to the Arduino and then disconnect the USB cable to remove power. Next, move on to building the practical layout shown in Fig. 7, which explains how to connect all the required components.

Required materials

The materials needed to build the project are:

• RFID-RC522 module
• Arduino UNO
• Breadboard with side power rails (red and black, or red and blue)
• 6×6 mm push button
• Red LED
• Blue LED (or another color of your choice)
• 2 resistors of 220 Ohm
• 1 resistor of 10 kOhm
• 5 M-M jumper wires
• 7 M-F jumper wires
• 1 jumper bridge, 3-pin
• 1 jumper bridge, 5-pin
• 1 jumper bridge, 19-pin
• 4 tags, one of which marked as administrator

Note that regarding jumper wires and bridges, we provided the list to replicate our exact practical layout; of course you can make any variation, as long as you correctly make the proposed connections, otherwise the circuit will not work. Above all, be extremely careful not to reverse the power supply (3.3V and GND), otherwise you risk burning the module!

A special note about the breadboard: during our tests we came across a model with the power rails interrupted in the middle section. This was actually clearly indicated by the break in the red and blue silkscreen lines, but since it is unusual, we initially did not notice it. As a result, the RC522 module’s LED still turned on (due to current carried by the signals), but tag reading did not work. We therefore had to add two jumper wires to connect the two rails along their entire length (Fig. 8), i.e., to bridge them.

How the access control works

Once the circuit is complete on the breadboard and the connections are checked, to begin simply reconnect the USB cable from the PC to the Arduino UNO board. You will see the RC522 module’s red LED light up (but as explained earlier, this does not indicate correct power supply), while the two red and blue LEDs on the breadboard remain off.

Now open the Serial Monitor of the Arduino IDE, and the message “Controllo accessi attivo” will appear. The first operation to perform is to bring the Administrator tag near the module. If everything is in order, the two LEDs will blink simultaneously three times and remain on; the Serial Monitor will also show the message visible in Fig. 9, indicating that Administrator mode is active.

If at first power-up a number other than 0 appears (usually it will be 255), you need to reset the EEPROM. Simply press the push button mounted on the breadboard to achieve the desired result (Fig. 10).

After the reset, you will exit Administrator mode and the LEDs will turn off. You must pass the Administrator tag again to re-enter, then simply bring the tag you want to authorize near the module to store its UID (Fig. 11).

This operation can be performed for a maximum of three tags; after that, no more can be stored unless you modify the sketch accordingly.

Daily use of the system

At this point we can observe the circuit’s behavior depending on the type of tag we bring near the RFID reader; there are two possibilities.

Unregistered tag: the red LED turns on for about three seconds, then turns off; authorization is denied.

Registered tag: if the blue LED is off, it turns on, indicating that authorization has been granted; the LED stays on until you pass the same tag or another registered tag, at which point it turns off.

One last curiosity: if you lack other tags to simulate unauthorized access, you can use your own smartphone. If you have a phone with an NFC chip running Android 5.0 or later, simply enable NFC in the settings and then use the smartphone as if it were a tag.

In fact, when you bring it near the module with the chip side facing it, it will be recognized as a tag, but with a peculiarity that prevents its use as an authorized tag: with each new read, the UID turns out to be different from the previous read. This is easily verifiable with the “RFID_TAG_CODE” sketch. So even if you store the chip as authorized, it will not be recognized on subsequent reads.

In some rare cases, the smartphone may need a specific app to function as a tag. Simply download “NFC Tools” from the Play Store and leave it active, without doing anything else.

Conclusions

We end this article with a suggestion: as you can easily imagine, this project can be expanded by adding, for example, a relay driven by the same pin as the blue LED, which would allow you to activate an actuator such as an electric lock. The only limits are those of your imagination.

Naturally, the greater the complexity of the expansion, the more variations and implementations you will need to make to the sketch, but it will all be a useful programming exercise that will increase your skills and give you great satisfaction.

The post RFID with RC522: Radio-Frequency Identification with Arduino appeared first on Open Electronics.

Sirojudin Munir has released an open-source FOC driver for BLDC and PMSM motors. The project includes firmware for STM32, hardware designed in KiCad, Gerber files, a BOM, and a Python GUI for control and monitoring. It is a complete resource for anyone who wants to build or study the vector control of a brushless motor. The permissive MIT license and the stated component cost of $28.58 make it accessible to many makers.

The heart of the system is the STM32F405 microcontroller, which runs the Field-Oriented Control calculations. The ADC reads current, the PWM drives the inverter, and SPI communicates with the magnetic encoder. The DRV8323RH gate driver manages the MOSFETs and also acts as a voltage regulator. The AS5047 encoder detects the rotor position, while the INA240A1 amplifier measures current with precision. All these components work together for efficient and responsive control.

How FOC control works

The firmware implements the Field-Oriented Control algorithm to manage motor torque and speed. The self-commissioning process measures motor resistance and inductance and calibrates the encoder. This way, the driver adapts to the connected motor without manual intervention. Several control modes are available: current, speed, position, open-loop, and motor disable. This flexibility makes the project suitable for many practical applications.

• Current control to manage torque
• Speed control with encoder feedback
• Position control for precision applications
• Open-loop mode for quick tests
• Full motor disable for safety

The PyQt/PyQtGraph GUI allows real-time data visualization and sending commands to the driver. The Python tools include functions for calibration and monitoring. Additionally, the improved client written by Munir simplifies system tuning. The project is designed to be studied and modified, with clear documentation and well-organized files.

Hardware and main components

The schematic and PCB are made in KiCad, with Gerber files ready for production. The board operates with voltages from 6 to 24 V and current up to 1 A. The 3-pin connector with 1.25 mm pitch makes motor connection easy. Those who want to study brushless control starting from something ready-made can look at a brushless motor driver with a Hall sensor: it does not do vector control, but it lets you see the inverter and power MOSFETs in action before making your own board. For testing, you will need a brushless motor.

The DRV8323RH gate driver is a key component: it drives the inverter MOSFETs and integrates a voltage regulator. The AS5047 magnetic encoder offers high resolution for rotor position. The INA240A1 measures current with a dedicated amplifier. These components are chosen to ensure reliable performance and good value for money.

Software tools and commissioning

The firmware compiles with PlatformIO in Visual Studio Code, starting from the STM32CubeMX configuration. The project board includes all the steps for commissioning. Self-commissioning automates the measurement of motor resistance and inductance. Encoder calibration is guided, reducing errors. Finally, the Python GUI lets you test the different control modes in real time.

Munir’s project is an excellent example of open-source technical documentation. It includes demonstration videos and clear instructions for reproduction. For those taking their first steps with brushless motors, this driver offers a solid foundation. Even those with experience can find interesting ideas in the design and firmware.

In summary, this is a complete, well-documented FOC driver with a permissive license. The component cost is low and the build quality is high. For anyone wanting to delve into brushless motor control, this is a project worth studying carefully. The combination of STM32, DRV8323RH, and AS5047 delivers remarkable performance in a compact format.

Source: https://github.com/sirojudinMunir/sf-motion

Related products

• Brushless motor

The post Open-Source FOC Driver for BLDC Motors: Sirojudin Munir’s Project appeared first on Open Electronics.

Sirojudin Munir has released an open-source FOC driver for BLDC and PMSM motors. The project includes firmware for STM32, hardware designed in KiCad, Gerber files, a BOM, and a Python GUI for control and monitoring. It is a complete resource for anyone who wants to build or study the vector control of a brushless motor. The permissive MIT license and the stated component cost of $28.58 make it accessible to many makers.

The heart of the system is the STM32F405 microcontroller, which runs the Field-Oriented Control calculations. The ADC reads current, the PWM drives the inverter, and SPI communicates with the magnetic encoder. The DRV8323RH gate driver manages the MOSFETs and also acts as a voltage regulator. The AS5047 encoder detects the rotor position, while the INA240A1 amplifier measures current with precision. All these components work together for efficient and responsive control.

How FOC control works

The firmware implements the Field-Oriented Control algorithm to manage motor torque and speed. The self-commissioning process measures motor resistance and inductance and calibrates the encoder. This way, the driver adapts to the connected motor without manual intervention. Several control modes are available: current, speed, position, open-loop, and motor disable. This flexibility makes the project suitable for many practical applications.

• Current control to manage torque
• Speed control with encoder feedback
• Position control for precision applications
• Open-loop mode for quick tests
• Full motor disable for safety

The PyQt/PyQtGraph GUI allows real-time data visualization and sending commands to the driver. The Python tools include functions for calibration and monitoring. Additionally, the improved client written by Munir simplifies system tuning. The project is designed to be studied and modified, with clear documentation and well-organized files.

Hardware and main components

The schematic and PCB are made in KiCad, with Gerber files ready for production. The board operates with voltages from 6 to 24 V and current up to 1 A. The 3-pin connector with 1.25 mm pitch makes motor connection easy. Those who want to study brushless control starting from something ready-made can look at a brushless motor driver with a Hall sensor: it does not do vector control, but it lets you see the inverter and power MOSFETs in action before making your own board. For testing, you will need a brushless motor.

The DRV8323RH gate driver is a key component: it drives the inverter MOSFETs and integrates a voltage regulator. The AS5047 magnetic encoder offers high resolution for rotor position. The INA240A1 measures current with a dedicated amplifier. These components are chosen to ensure reliable performance and good value for money.

Software tools and commissioning

The firmware compiles with PlatformIO in Visual Studio Code, starting from the STM32CubeMX configuration. The project board includes all the steps for commissioning. Self-commissioning automates the measurement of motor resistance and inductance. Encoder calibration is guided, reducing errors. Finally, the Python GUI lets you test the different control modes in real time.

Munir’s project is an excellent example of open-source technical documentation. It includes demonstration videos and clear instructions for reproduction. For those taking their first steps with brushless motors, this driver offers a solid foundation. Even those with experience can find interesting ideas in the design and firmware.

In summary, this is a complete, well-documented FOC driver with a permissive license. The component cost is low and the build quality is high. For anyone wanting to delve into brushless motor control, this is a project worth studying carefully. The combination of STM32, DRV8323RH, and AS5047 delivers remarkable performance in a compact format.

Source: https://github.com/sirojudinMunir/sf-motion

Related products

• Brushless motor

The post Open-Source FOC Driver for BLDC Motors: Sirojudin Munir’s Project appeared first on Open Electronics.

Phil Underwood has spent twenty years mapping underground caves. His work has produced a series of open hardware devices that increase the speed and accuracy of surveys. The journey starts with tools based on 8-bit microcontrollers and arrives at a complete photogrammetry system. Each generation solved a specific problem, improving the design incrementally.

The first version, presented in 2008, used an accelerometer and a magnetometer to determine direction and angle. Distance, however, was still measured manually. The heart of the system was a PIC18LF2550, an 8-bit microcontroller. This approach proved that part of the survey could be automated, but human intervention was still needed for linear measurements.

The turning point came in 2020. Phil added a laser rangefinder and a 32-bit microcontroller. This allowed the device to calculate distances autonomously and handle more complex operations. Data collection also became faster and less error-prone. The move from 8 to 32 bits made it possible to process more information directly in the field.

Improved design and community

In 2023 the project received special attention. The enclosure was 3D-printed, with silicone buttons resistant to water and dust. The firmware moved to CircuitPython, a language that makes community contributions easier. Many makers were able to modify the code without deep electronics knowledge. This accelerated development and made the project more open.

Choosing CircuitPython made the code more readable and easier to maintain. 3D printing also allowed custom enclosures for each environment. The modular design made it simple to replace damaged components. As a result, the device became a reliable tool for cavers.

• 2008: accelerometer, magnetometer, PIC18LF2550 8-bit
• 2020: laser rangefinder and 32-bit microcontroller
• 2023: 3D-printed enclosure and CircuitPython firmware

Latest version: Raspberry Pi 5 Compute Module and photogrammetry

The latest generation represents a technological leap. The system uses a Raspberry Pi 5 Compute Module and two low-light cameras. The cameras capture images of the cave interior, then the software processes them to create textured 3D models. This approach eliminates the need to measure every point manually. The result is a detailed and realistic map.

For those wanting to experiment with similar sensors, a 9-axis module with accelerometer, gyroscope, and magnetometer combines in one unit the two measurements that supported the 2008 version. For processing, a Raspberry Pi 5 with 4 GB of RAM handles photogrammetry without strain, and a 5-megapixel camera for Raspberry Pi is the cheapest way to try dual capture.

Phil Underwood’s project shows a methodical approach to hardware design. Every choice, from materials to computing power, was guided by the real needs of cavers. The lessons learned apply to any rugged instrumentation. In particular, modularity and ease of maintenance are essential in extreme environments.

Lessons for makers

The story of this project teaches that incremental evolution works. You start with a simple prototype, test it in the field, then improve it. Each generation solved a concrete problem. Moreover, openness to the community accelerated the process. Documentation and code are available for anyone who wants to contribute.

Cave mapping with photogrammetry is just the latest milestone. The complete system, with Raspberry Pi 5 Compute Module, is an example of how open source hardware can tackle complex challenges. The device is called Shetland Attack Pony, and the sixth generation (SAP6) is fully documented: schematics, component list, and CircuitPython code are public.

Source: https://stic.readthedocs.io/

The post Mapping Caves with Photogrammetry and Raspberry Pi appeared first on Open Electronics.

Phil Underwood has spent twenty years mapping underground caves. His work has produced a series of open hardware devices that increase the speed and accuracy of surveys. The journey starts with tools based on 8-bit microcontrollers and arrives at a complete photogrammetry system. Each generation solved a specific problem, improving the design incrementally.

The first version, presented in 2008, used an accelerometer and a magnetometer to determine direction and angle. Distance, however, was still measured manually. The heart of the system was a PIC18LF2550, an 8-bit microcontroller. This approach proved that part of the survey could be automated, but human intervention was still needed for linear measurements.

The turning point came in 2020. Phil added a laser rangefinder and a 32-bit microcontroller. This allowed the device to calculate distances autonomously and handle more complex operations. Data collection also became faster and less error-prone. The move from 8 to 32 bits made it possible to process more information directly in the field.

Improved design and community

In 2023 the project received special attention. The enclosure was 3D-printed, with silicone buttons resistant to water and dust. The firmware moved to CircuitPython, a language that makes community contributions easier. Many makers were able to modify the code without deep electronics knowledge. This accelerated development and made the project more open.

Choosing CircuitPython made the code more readable and easier to maintain. 3D printing also allowed custom enclosures for each environment. The modular design made it simple to replace damaged components. As a result, the device became a reliable tool for cavers.

• 2008: accelerometer, magnetometer, PIC18LF2550 8-bit
• 2020: laser rangefinder and 32-bit microcontroller
• 2023: 3D-printed enclosure and CircuitPython firmware

Latest version: Raspberry Pi 5 Compute Module and photogrammetry

The latest generation represents a technological leap. The system uses a Raspberry Pi 5 Compute Module and two low-light cameras. The cameras capture images of the cave interior, then the software processes them to create textured 3D models. This approach eliminates the need to measure every point manually. The result is a detailed and realistic map.

For those wanting to experiment with similar sensors, a 9-axis module with accelerometer, gyroscope, and magnetometer combines in one unit the two measurements that supported the 2008 version. For processing, a Raspberry Pi 5 with 4 GB of RAM handles photogrammetry without strain, and a 5-megapixel camera for Raspberry Pi is the cheapest way to try dual capture.

Phil Underwood’s project shows a methodical approach to hardware design. Every choice, from materials to computing power, was guided by the real needs of cavers. The lessons learned apply to any rugged instrumentation. In particular, modularity and ease of maintenance are essential in extreme environments.

Lessons for makers

The story of this project teaches that incremental evolution works. You start with a simple prototype, test it in the field, then improve it. Each generation solved a concrete problem. Moreover, openness to the community accelerated the process. Documentation and code are available for anyone who wants to contribute.

Cave mapping with photogrammetry is just the latest milestone. The complete system, with Raspberry Pi 5 Compute Module, is an example of how open source hardware can tackle complex challenges. The device is called Shetland Attack Pony, and the sixth generation (SAP6) is fully documented: schematics, component list, and CircuitPython code are public.

Source: https://stic.readthedocs.io/

The post Mapping Caves with Photogrammetry and Raspberry Pi appeared first on Open Electronics.

Pi-Ener-lite is a compact UPS power supply designed by ACE design studio for the Raspberry Pi Zero. It connects to the board via 7 spring-loaded pogo pins, which handle both power delivery and data reading. The project integrates an 18650 battery, a CW2015 fuel gauge chip, and a DS1307 RTC chip, offering a complete uninterruptible power supply in a small footprint.

Operation is simple and reliable. When external power is lost, the system automatically switches to battery power. It also supports simultaneous charging and discharging, so you can use the Raspberry Pi Zero while the battery recharges. The whole setup is protected against overcharge, over-discharge, overcurrent, and short circuits.

Battery measurement and RTC

The CW2015 fuel gauge chip measures battery voltage and remaining capacity with ±2% accuracy. The DS1307 RTC chip, powered by a CR1220 coin cell, keeps time even when the main battery is removed. This combination makes Pi-Ener-lite a truly complete UPS for applications that require operational continuity.

Fuel gauge and RTC data are read over I2C, so you can access them easily from Python. The project includes Python examples and detailed documentation. An optional open-source 3D-printable case protects the entire system. Total cost is around $35.

Why choose Pi-Ener-lite

Pi-Ener-lite is a compact UPS specifically for the Pi Zero. Unlike other solutions, it leaves the GPIO connector free, so you can attach other modules without issues. It also adds battery measurement and an RTC, two features often missing from DIY UPS builds. The open-source 3D-printable case adds versatility.

The project is designed for those who want a reliable backup power supply without taking up space. The board connects in seconds thanks to the spring-loaded pogo pins. The CW2015 fuel gauge lets you monitor remaining charge precisely, avoiding sudden shutdowns. If you need a professional solution for your Pi Zero, this project fits the bill.

• Connection via 7 spring-loaded pogo pins, no soldering
• 18650 battery with CW2015 fuel gauge for charge monitoring
• DS1307 RTC with CR1220 battery to keep time
• Protection against overcharge, over-discharge, overcurrent, and short circuits
• Open-source 3D-printable case

To build the project, you need an 18650 battery and a CR1220 coin cell. The rest of the components are already mounted on the board. If you want to power the system from a higher voltage, you can use a 12V DC-DC step-up converter to adapt the input. Alternatively, for industrial applications, consider a DC-DC converter with 36-48V input and 24V output.

Getting started with Pi-Ener-lite

The first step is to connect the board to the Raspberry Pi Zero via the pogo pins. Then install the drivers for the CW2015 and DS1307. Finally, write a simple Python script to read voltage and time. The project board includes ready-to-use examples.

If you want a more powerful system, you can pair Pi-Ener-lite with a Raspberry Pi 5. In that case, you must adapt the power supply, because the Pi 5 requires more current. For the Pi Zero, the solution works perfectly as is. The project is designed to be simple, compact, and reliable.

In conclusion, Pi-Ener-lite is a well-designed UPS with quality components and clear documentation. The ability to print a 3D case makes it even more versatile. If you’re looking for a backup power supply for your Raspberry Pi Zero, this project deserves attention.

The post Pi-Ener-lite: Compact UPS with Fuel Gauge and RTC for Raspberry Pi Zero appeared first on Open Electronics.

Pi-Ener-lite is a compact UPS power supply designed by ACE design studio for the Raspberry Pi Zero. It connects to the board via 7 spring-loaded pogo pins, which handle both power delivery and data reading. The project integrates an 18650 battery, a CW2015 fuel gauge chip, and a DS1307 RTC chip, offering a complete uninterruptible power supply in a small footprint.

Operation is simple and reliable. When external power is lost, the system automatically switches to battery power. It also supports simultaneous charging and discharging, so you can use the Raspberry Pi Zero while the battery recharges. The whole setup is protected against overcharge, over-discharge, overcurrent, and short circuits.

Battery measurement and RTC

The CW2015 fuel gauge chip measures battery voltage and remaining capacity with ±2% accuracy. The DS1307 RTC chip, powered by a CR1220 coin cell, keeps time even when the main battery is removed. This combination makes Pi-Ener-lite a truly complete UPS for applications that require operational continuity.

Fuel gauge and RTC data are read over I2C, so you can access them easily from Python. The project includes Python examples and detailed documentation. An optional open-source 3D-printable case protects the entire system. Total cost is around $35.

Why choose Pi-Ener-lite

Pi-Ener-lite is a compact UPS specifically for the Pi Zero. Unlike other solutions, it leaves the GPIO connector free, so you can attach other modules without issues. It also adds battery measurement and an RTC, two features often missing from DIY UPS builds. The open-source 3D-printable case adds versatility.

The project is designed for those who want a reliable backup power supply without taking up space. The board connects in seconds thanks to the spring-loaded pogo pins. The CW2015 fuel gauge lets you monitor remaining charge precisely, avoiding sudden shutdowns. If you need a professional solution for your Pi Zero, this project fits the bill.

• Connection via 7 spring-loaded pogo pins, no soldering
• 18650 battery with CW2015 fuel gauge for charge monitoring
• DS1307 RTC with CR1220 battery to keep time
• Protection against overcharge, over-discharge, overcurrent, and short circuits
• Open-source 3D-printable case

To build the project, you need an 18650 battery and a CR1220 coin cell. The rest of the components are already mounted on the board. If you want to power the system from a higher voltage, you can use a 12V DC-DC step-up converter to adapt the input. Alternatively, for industrial applications, consider a DC-DC converter with 36-48V input and 24V output.

Getting started with Pi-Ener-lite

The first step is to connect the board to the Raspberry Pi Zero via the pogo pins. Then install the drivers for the CW2015 and DS1307. Finally, write a simple Python script to read voltage and time. The project board includes ready-to-use examples.

If you want a more powerful system, you can pair Pi-Ener-lite with a Raspberry Pi 5. In that case, you must adapt the power supply, because the Pi 5 requires more current. For the Pi Zero, the solution works perfectly as is. The project is designed to be simple, compact, and reliable.

In conclusion, Pi-Ener-lite is a well-designed UPS with quality components and clear documentation. The ability to print a 3D case makes it even more versatile. If you’re looking for a backup power supply for your Raspberry Pi Zero, this project deserves attention.

The post Pi-Ener-lite: Compact UPS with Fuel Gauge and RTC for Raspberry Pi Zero appeared first on Open Electronics.

Pi-Ener-lite is a compact UPS for Raspberry Pi Zero with a CW2015 fuel gauge, DS1307 RTC, and 18650 battery support, all connected via spring-loaded pogo pins.

SonicFly lets a drone follow another using only the sound of the leader's rotors—no GPS, cameras, or radio. Built by Yanbaihui Liu, it uses a four-microphone array, neural network, and Kalman filter to estimate position acoustically.

PyBLE is an open-source MicroPython IDE that communicates over Bluetooth LE, letting you code, run, and debug ESP32 boards wirelessly from a tablet or iPad—no cloud, no USB cable, no PC required.

Control a gate or other electronic devices from your smartphone using the Ganimede.E12 board and a dedicated mobile app, with a focus on privacy and security.

Gemma Translator is an open-source multilingual voice interpreter for Raspberry Pi 5 that runs entirely on-device, using Google Gemma 4 and LiteRT, with a retro-terminal UI and no cloud dependency.

A maker known as PRBS23 has freed the MasterBuilt Gravity 800 Grill controller from proprietary firmware, replacing it with an open source firmware featuring PID temperature control, over-the-air updates, and a real-time web interface.

Build a simple seven-note electronic keyboard using the versatile 555 timer IC. This project explains the astable multivibrator configuration and how to calculate resistor values for musical notes.

Build a no-code ePaper weather dashboard with the Seeed Studio XIAO EE05 and SenseCraft Seeedash. Drag-and-drop widgets, flash firmware, and display temperature, humidity, wind, and more on a 4.26-inch ePaper screen.