139 lines
4.1 KiB
Markdown
139 lines
4.1 KiB
Markdown
# New Meshtastic Module
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Guide for developing a new Meshtastic firmware module.
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## Module Hierarchy
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Choose the appropriate base class:
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1. **`MeshModule`** - Raw base class. Override `wantPacket()` and `handleReceived()`. Returns `ProcessMessage::STOP` or `ProcessMessage::CONTINUE`.
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2. **`SinglePortModule`** - Handles a single `meshtastic_PortNum`. Constructor takes `(name, portNum)`. Simplified `wantPacket()` checking `decoded.portnum`. Use `allocDataPacket()` to create outgoing packets.
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3. **`ProtobufModule<T>`** - Template for protobuf-encoded modules. Constructor takes `(name, portNum, fields)`. Override `handleReceivedProtobuf()`. Use `allocDataProtobuf(payload)` to create outgoing packets.
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Most modules also mix in `concurrency::OSThread` for periodic background tasks.
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## Implementation Pattern
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```cpp
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// src/modules/MyModule.h
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#pragma once
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#include "ProtobufModule.h"
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#include "concurrency/OSThread.h"
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class MyModule : public ProtobufModule<meshtastic_MyMessage>, private concurrency::OSThread
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{
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public:
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MyModule();
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protected:
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// Process incoming protobuf packet. Return true to stop further processing.
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virtual bool handleReceivedProtobuf(const meshtastic_MeshPacket &mp, meshtastic_MyMessage *msg) override;
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// Generate response packet (optional)
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virtual meshtastic_MeshPacket *allocReply() override;
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// Periodic task - return next run interval in ms, or disable()
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virtual int32_t runOnce() override;
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// Modify packet in-flight before delivery (optional)
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virtual bool alterReceivedProtobuf(meshtastic_MeshPacket &mp, meshtastic_MyMessage *msg);
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// Request a UI display frame (optional)
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virtual bool wantUIFrame();
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};
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```
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## Registration
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Register in `src/modules/Modules.cpp` inside `setupModules()`:
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```cpp
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#if !MESHTASTIC_EXCLUDE_MYMODULE
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new MyModule();
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#endif
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```
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If other code needs to reference the module instance:
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```cpp
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#if !MESHTASTIC_EXCLUDE_MYMODULE
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myModule = new MyModule();
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#endif
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```
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And declare the global in the header:
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```cpp
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extern MyModule *myModule;
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```
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Some modules also conditionally instantiate based on `moduleConfig`:
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```cpp
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#if !MESHTASTIC_EXCLUDE_MYMODULE
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if (moduleConfig.has_my_module && moduleConfig.my_module.enabled) {
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new MyModule();
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}
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#endif
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```
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## Conditional Compilation
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Add a `MESHTASTIC_EXCLUDE_MYMODULE` guard. This allows the module to be excluded from constrained builds. The flag name must follow the pattern: `MESHTASTIC_EXCLUDE_` + uppercase module name.
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## Protobuf Messages (if needed)
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1. Define messages in `protobufs/meshtastic/` (e.g., `mymodule.proto`)
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2. Add a `.options` file for nanopb field size constraints
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3. Regenerate with `bin/regen-protos.sh`
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4. Generated code appears in `src/mesh/generated/meshtastic/`
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5. Assign a `meshtastic_PortNum` if the module uses a new port number
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## Timing and Defaults
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Use `Default` class helpers for configurable intervals:
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```cpp
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int32_t MyModule::runOnce()
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{
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uint32_t interval = Default::getConfiguredOrDefaultMs(moduleConfig.my_module.update_interval,
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default_my_module_interval);
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// ... do work ...
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return interval;
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}
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```
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On public/default channels, enforce minimums with `Default::getConfiguredOrMinimumValue()`.
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## Observer Pattern
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Subscribe to system events:
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```cpp
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CallbackObserver<MyModule, const meshtastic::Status *> statusObserver =
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CallbackObserver<MyModule, const meshtastic::Status *>(this, &MyModule::handleStatusUpdate);
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```
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## Testing
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Add test suite in `test/test_mymodule/`:
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```text
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test/
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└── test_mymodule/
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└── test_main.cpp
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```
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Run with: `pio test -e native`
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## Checklist
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- [ ] Header and implementation files in `src/modules/`
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- [ ] Inherit from appropriate base class (MeshModule / SinglePortModule / ProtobufModule)
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- [ ] Mix in OSThread if periodic work is needed
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- [ ] Register in `src/modules/Modules.cpp` with `MESHTASTIC_EXCLUDE_` guard
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- [ ] Add protobuf definitions if needed (`protobufs/meshtastic/`)
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- [ ] Use `Default::getConfiguredOrDefaultMs()` for timing
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- [ ] Respect bandwidth limits on public channels
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- [ ] Add test suite in `test/`
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