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](/downloads) page. If you wish to view the code or contribute to development of the firmware, please visit the device code [GitHub page](https://github.com/meshtastic/firmware).
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.
You can get the latest python tool/library with `pip3 install --upgrade meshtastic` on Windows/Linux/OS-X. See the [python section](/docs/software/python/cli/installation) 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:
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.
You can programmatically do operations from your own python code by using the Meshtastic `RemoteHardwareClient` class. See the [Python API](/docs/software/python/cli/installation) documentation for more details.
You can add a simple LED and resistor to validate that the GPIO operations work as expected. Use [this tutorial](https://www.instructables.com/Slide-Switch-With-Arduino-Uno-R3/) as a guide.
- (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) 220Ω resistor (somewhat optional, but recommended)
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
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`.
