DIY Meshtastic - How To Build Your Own Meshtastic Device with FakeTec PCB & NRF52840

Adrelien -

Learn how to build your own low-cost Meshtastic node using the FakeTec PCB design, NRF52840 Pro Micro, and an HT-RA62 LoRa module. This compact and efficient build offers the perfect balance between affordability and functionality for your mesh communication needs.

Hardware

Here's what you'll need to get started:

Total build cost: ~$11.00 (excluding shipping and any optional components)

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This guide focuses on creating a basic functioning Meshtastic node. The FakeTec PCB design supports additional components like GPS, but we're keeping it simple for now. You can always expand functionality later by adding the resistors, MOSFETs, and other components suggested in the original repository.

PCB Ordering

To order the PCB from JLCPCB:

  1. Navigate to JLCPCB's quote page
  2. Download the latest Gerber files (v4) from the FakeTec PCB repository
  3. Upload the Gerber ZIP file to JLCPCB
  4. Keep all the default PCB settings (you can change the PCB color if desired)
  5. Place your order and await delivery

Component Details

NRF52840 Pro Micro

The NRF52840 Pro Micro is an excellent choice for building a Meshtastic LoRa Node. This compact board features:

  • Integrated Battery Management System (BMS)
  • Bluetooth connectivity
  • Very low power consumption
  • Small form factor

This allows your node to run on a small battery for days. However, it's important to note that the NRF52840 does not have WiFi capabilities, so features like the PAX counter or connecting to MQTT via WiFi won't be available. This board is best suited for applications that rely on Bluetooth and LoRa communication.

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It is not recommended to use a battery larger than 450mAh with this board. Although this limitation is not officially documented, some users (e.g., on Reddit) have reported instability or charging issues with larger batteries.

If you plan to use a larger battery, you must short the BOOST pads on the back of the board (located next to RST and VCC).

Battery Charge Current: Without BOOST jumper: 100mA | With BOOST jumper: 300mA

HT-RA62 LoRa Module

The HT-RA62 LoRa module is a compact, surface-mount (SMC) version of the popular LoRa radio, designed for integration into custom PCBs. Unlike the RA-02 DIP version, which features through-hole pins and is suitable for breadboarding and prototyping, the HT-RA62 requires more advanced soldering techniques and precise manual soldering. This trade-off, however, allows for a much slimmer and more space-efficient design.

The module supports both 433 MHz and 868/915 MHz frequency bands, depending on the specific model, offering flexibility for deployment across different regions in compliance with ISM band regulations. Built on the Semtech SX1262 newer chipset (typically the SX1276 or SX1278), it delivers high sensitivity and long-range communication capabilities.

Assembly

Since we're working with surface-mount components, this assembly will be more challenging than using through-hole components. Take your time and practice before starting if you're new to SMC soldering.

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We will only cover the bare minimum required to get the device running. If you want to utilize the full capabilities of the PCB, you’ll need to follow the suggestions on GitHub to add the additional MOSFET and resistors.

Step 1: Prepare the Pro Micro and PCB

  1. Align the Pro Micro board with the holes on the PCB
  2. Ensure the USB port is facing outward, and the PCB is facing up
  3. You should see the Pro Micro on top with the PCB underneath, and above the Pro Micro, the two columns of 8 pads designated for the LoRa module

Step 2: Install and Solder the Pro Micro

  1. Insert the header pins that came with the Pro Micro from the bottom of the PCB
  2. Push the pins through the PCB and then through the Pro Micro
  3. Place the entire assembly on a table with the pins pointing up
  4. Use tape to secure it in place if needed
  5. Begin soldering the pins
  6. Once all pins are soldered from the top, flip the board and break the black plastic holding the pins together using a small cutter (like those that come with 3D printers). Break it in chunks every 4 pins make a break. It will make it so much easier to remove it later on.
  7. Carefully peel away the plastic with the cutter tip
  8. Once all pins are soldered from the top and the plastic removed, solder from the bottom side for better conductivity
  9. Using wire cutters, trim the excess pins that stick out
  10. Cool down the Pro Micro first, then plug it into a power source to test if it still works
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Wear eye protection! The cut pins can fly off in all directions.

Step 3: Solder the LoRa Module

  1. Orient the LoRa module with the IPEX connector positioned at the top left corner
  2. Align it carefully with the pads on the PCB
  3. Since there are no pins to hold it in place, use electrical tape to secure it temporarily. Pro tip: Stretching the electrical tape makes it narrower, which can help secure the module to the board
  4. Begin by soldering one corner pad (GND or ANT is recommended)
  5. Once the first joint is complete, the module should be stable enough to continue soldering the remaining pads
  6. Take breaks as needed and work carefully - there's no rush!
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For SMC soldering, apply a small amount of solder to the pad first, then hold the component in place with tweezers while reheating the solder. This "tack soldering" approach makes alignment much easier.
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After completing the wiring, it's crucial not to forget to connect your antenna

Flashing The Software

Before using your Meshtastic node, you'll need to flash it with the appropriate firmware.

Step 1: Update the Bootloader

Most NRF52840 Pro Micro boards come with an outdated bootloader version that needs updating:

  1. Connect the node to your PC using a data cable
  2. Put the node into DFU (Device Firmware Update) mode by shorting the GND and Reset pins once or twice
  3. A new drive should appear on your computer
  4. Check the INFO_UF2.TXT file to determine your current bootloader version
  5. Visit Adafruit's GitHub page for nRF52 Bootloader releases
  6. Find the next release after your current version (you must update incrementally)
  7. Download the nice_nano_bootloader-X.X.X.HEX and nice_nano_bootloader-X.X.X.UF2 files for your board
  8. Drag and drop the .HEX file onto the drive first, then the .UF2 file
  9. The device will disconnect and restart
  10. Check the bootloader version again and repeat if necessary until you reach the latest version

Step 2: Install Meshtastic Firmware

  1. Visit the Meshtastic web flasher
  2. Select "NRF52 Pro-micro DIY variant" from the list
  3. Download the UF2 file
  4. Put your node in DFU mode again
  5. Drag and drop the downloaded UF2 file onto the drive
  6. Wait for the device to restart (this may take a minute or two)

Pairing Devices

With the hardware assembled and the firmware flashed, you're now ready to pair your FakeTec Meshtastic node with your phone:

  1. Download the Meshtastic app on your phone (available for both iOS and Android)
  2. Navigate to the Bluetooth page and wait for your device to appear
  3. Select your Meshtastic device from the list
  4. When prompted for a pairing PIN, enter "123456"
  5. Select your region based on your LoRa frequency (e.g., "EU433" for 433MHz modules)
  6. The node will restart, and you'll be ready to go!

Conclusion

Building your own Meshtastic node with the FakeTec PCB design offers an excellent balance of cost-effectiveness and functionality. At approximately $11 for the basic components, this DIY approach makes mesh networking accessible to hobbyists and enthusiasts.

The assembly process, while requiring some soldering skill, is straightforward when following the step-by-step instructions. The NRF52840 Pro Micro's integrated battery management and Bluetooth capabilities, combined with the compact HT-RA62 LoRa module, create a power-efficient node perfect for off-grid communication.