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Configuring GPIO Peripherals

Firmware Versionsโ€‹

danger

GPIO access is fundamentally dangerous because invalid options can physically damage or destroy your hardware. Ensure that you fully understand the schematic for your particular device before trying this as we do not offer a warranty. Use at your own risk.

The device firmware runs on the nodes to build the mesh for communication. Each different make and model of device requires a different build of the Meshtastic firmware in order to run properly. Thankfully, due to the design of Meshtastic, it is possible to port the firmware to new devices as they become available. The firmware currently runs on a range of ESP32 based devices, but there is also increasing support for the nRF52 microprocessor with some more recent devices coming to market.

The current firmware has support for a screen to display received messages, along with information about nodes on the mesh, and more detailed information about the device on which it is running.

The latest firmware can be downloaded from the Downloads page. If you wish to view the code or contribute to development of the firmware, please visit the device code GitHub page.

info

Please be aware that there are significant changes between version branches 1.2.x and 1.3.x which mean that devices need to be running the same branch of firmware to be able to talk to each other. Python, Android, and other software applications will also need to be running the same branch to be able to talk to the device.

This feature uses a preinstalled module in the device code and associated command line flags/classes in the python code. You'll need to be running at least version 1.2.23 (or later) of the python and device code to use this feature.

Remote Hardwareโ€‹

Supported Operationsโ€‹

  • Set any GPIO
  • Read any GPIO
  • Receive notification of changes in any GPIO

Setupโ€‹

You can get the latest python tool/library with pip3 install --upgrade meshtastic on Windows/Linux/OS-X. See the python section for more details.

To prevent access from untrusted users, you must first make a gpio channel that is used for authenticated access to this feature. You'll need to install this channel on both the local and remote node.

The procedure using the python command line tool is:

  1. Connect local device via USB
  2. Create a GPIO channel:
    meshtastic --ch-add gpio
  3. If doing local testing, you may also want to change the speed of the channel:
    meshtastic --ch-mediumfast
  4. Check the channel has been created and copy the long "Complete URL" that contains all the channels on that device:
    meshtastic --info
  5. Connect the remote device via USB (or use the remote admin feature to reach it through the mesh)
  6. Set it to join the gpio channel you created:
    meshtastic --seturl theurlyoucopiedinstep3

Now both devices should be able to talk over the gpio channel. Send a text message from one the other other verify. Also run --nodes to verify the second node shows up.

Masksโ€‹

To determine the appropriate mask for the pin(s) that you want to know. The python program (and output) below might help:

>>> for i in range(1,45):
... print(f'GPIO:{i} mask:{hex(2**i)}')
...
GPIO:1 mask:0x2
GPIO:2 mask:0x4
GPIO:3 mask:0x8
GPIO:4 mask:0x10
GPIO:5 mask:0x20
GPIO:6 mask:0x40
GPIO:7 mask:0x80
GPIO:8 mask:0x100
GPIO:9 mask:0x200
GPIO:10 mask:0x400
GPIO:11 mask:0x800
GPIO:12 mask:0x1000
GPIO:13 mask:0x2000
GPIO:14 mask:0x4000
GPIO:15 mask:0x8000
GPIO:16 mask:0x10000
GPIO:17 mask:0x20000
GPIO:18 mask:0x40000
GPIO:19 mask:0x80000
GPIO:20 mask:0x100000
GPIO:21 mask:0x200000
GPIO:22 mask:0x400000
GPIO:23 mask:0x800000
GPIO:24 mask:0x1000000
GPIO:25 mask:0x2000000
GPIO:26 mask:0x4000000
GPIO:27 mask:0x8000000
GPIO:28 mask:0x10000000
GPIO:29 mask:0x20000000
GPIO:30 mask:0x40000000
GPIO:31 mask:0x80000000
GPIO:32 mask:0x100000000
GPIO:33 mask:0x200000000
GPIO:34 mask:0x400000000
GPIO:35 mask:0x800000000
GPIO:36 mask:0x1000000000
GPIO:37 mask:0x2000000000
GPIO:38 mask:0x4000000000
GPIO:39 mask:0x8000000000
GPIO:40 mask:0x10000000000
GPIO:41 mask:0x20000000000
GPIO:42 mask:0x40000000000
GPIO:43 mask:0x80000000000
GPIO:44 mask:0x100000000000

Testing GPIO Operationsโ€‹

You can programmatically do operations from your own python code by using the Meshtastic RemoteHardwareClient class. See the Python API documentation for more details.

You can add a simple LED and resistor to validate that the GPIO operations work as expected. Use this tutorial as a guide.

Requirementsโ€‹

  • (x2) Meshtastic devices (one device could be on a local computer, and the other one just has to be powered and is the one with the LED to be connected to it)
  • (x2) wires (black and yellow; they can be any color but typically black is used for ground)
  • (x1) LED
  • (x1) 220ฮฉ resistor (somewhat optional, but recommended)
  • (x1) Breadboard (optional)

Preparationโ€‹

  1. Disconnect the remote device from power (battery/usb)
  2. Add a resistor from yellow wire to the one end of the LED (either end of the resistor is OK, either end of the LED is OK)
  3. Add the yellow wire from a GPIO pin that will not cause any issues (ex: for TLoraV1, we can use GPIO21)
  4. Add the black "ground" wire from the ground pin on the device (ex: for TLoraV1 it is the end pin next to the RST button) to the other end of the LED
  5. Power on the device

Validationโ€‹

By default, the pin may be "off" or "on". (It will most likely "off".) See the steps below for running commands. In the example of GPIO21, the mask would be 0x200000.

T-Lora v1 with LED on GPIO 21

Using GPIOs from the Python CLIโ€‹

Writing a GPIOโ€‹

Example: turning 'on' GPIO4
meshtastic  --port /dev/ttyUSB0 --gpio-wrb 4 1 --dest 28979058
# Connected to radio
# Writing GPIO mask 0x10 with value 0x10 to !28979058

Reading a GPIOโ€‹

Example: read GPIO4
meshtastic --port /dev/ttyUSB0 --gpio-rd 0x10 --dest 28979058
# Connected to radio
# Reading GPIO mask 0x10 from !28979058
# GPIO read response gpio_value=16
note

If the mask and the gpio_value match, then the value is "on". If the gpio_value is 0, then the value is "off".

Watching for GPIO Changesโ€‹

Example: watching GPIO4 for changes
meshtastic --port /dev/ttyUSB0 --gpio-watch 0x10 --dest 28979058
# Connected to radio
# Watching GPIO mask 0x10 from !28979058
# Received RemoteHardware typ=GPIOS_CHANGED, gpio_value=16
# Received RemoteHardware typ=GPIOS_CHANGED, gpio_value=0
# Received RemoteHardware typ=GPIOS_CHANGED, gpio_value=16
# < press ctrl-c to exit >