# MicroMesh

MicroMesh is a small, dependency-free Meshtastic client for MicroPython. It talks to a
Meshtastic device over its serial API and implements the protobuf wire format directly,
so `google.protobuf`, threads, and `pyserial` are not required.

The initial release supports:

- serial `ToRadio` / `FromRadio` framing and resynchronization;
- the configuration handshake and a small in-memory node list;
- text, arbitrary data, and position packets;
- routing acknowledgements, node/user data, waypoints, and device metrics;
- familiar generated-protobuf methods: `SerializeToString`, `ParseFromString`,
  `CopyFrom`, `HasField`, `ClearField`, and `WhichOneof`;
- preservation of unknown protobuf fields for forward compatibility.

This is intentionally not a complete replacement for the desktop
[`meshtastic`](https://github.com/meshtastic/python) package. Configuration and admin
messages are currently returned as raw encoded bytes.

## Install

From a checkout of this repository, install with a current `mpremote`:

```sh
mpremote mip install package.json
```

Alternatively, copy the `micromesh` directory to `/lib` on the board. After this
repository is published on GitHub it can also be installed as
`mpremote mip install github:ORG/micromesh`.

It can also be installed on CPython for development:

```sh
python -m pip install .
```

## Quick start

```python
from machine import UART, Pin
from micromesh import PortNum, SerialInterface

uart = UART(1, baudrate=115200, tx=Pin(17), rx=Pin(16), timeout=0)

def received(packet):
    if packet.WhichOneof("payload_variant") != "decoded":
        return
    if packet.decoded.portnum == PortNum.TEXT_MESSAGE_APP:
        print("from !%08x:" % packet.from_, packet.decoded.payload.decode())

mesh = SerialInterface(uart, on_packet=received)
mesh.connect()
mesh.sendText("hello mesh")

while True:
    mesh.poll()
```

The UART baud rate and pins depend on the attached Meshtastic device. `poll()` is
non-blocking when the UART is configured with `timeout=0`.

Direct messages accept either an integer or Meshtastic's hexadecimal node ID:

```python
mesh.sendText("hello", destinationId="!a1b2c3d4", wantAck=True)
mesh.sendPosition(45.5152, -122.6784, altitude=15)
mesh.sendData(b"custom", portNum=PortNum.PRIVATE_APP)
```

## Protobufs

Messages can be used without a radio:

```python
from micromesh import Data, PortNum

data = Data(portnum=PortNum.TEXT_MESSAGE_APP, payload=b"hello")
encoded = data.SerializeToString()
decoded = Data().ParseFromString(encoded)
```

Generated-module-style imports are available as `micromesh.mesh_pb2` and
`micromesh.portnums_pb2` for easier porting from the desktop library.

Only the commonly useful schemas are modeled. Unknown fields survive a decode/encode
round trip, but their contents are not interpreted. A field named `from` is accessed as
`packet.from_` because `from` is a Python keyword.

## Development

```sh
python -m unittest discover -s tests
```

The API protocol is defined by the
[`meshtastic/protobufs`](https://github.com/meshtastic/protobufs) project. Update the
field declarations in `micromesh/messages.py` when adopting newer schemas.

`manifest.py` is also included for freezing the package into custom MicroPython firmware.