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This commit refactors the serial bridge functionality out of the `simple_repeater` example and into a more reusable, object-oriented structure. An `AbstractBridge` interface has been introduced, along with a concrete `SerialBridge` implementation. This encapsulates all the logic for packet framing, checksum calculation, and serial communication, cleaning up the main example file significantly. The `simple_repeater` example now instantiates and uses the `SerialBridge` class, resulting in better separation of concerns and improved code organization.pull/454/head
João Brázio
9 months ago
4 changed files with 171 additions and 98 deletions
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#pragma once |
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#include <Mesh.h> |
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class AbstractBridge { |
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public: |
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virtual ~AbstractBridge() {} |
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/**
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* @brief Initializes the bridge. |
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*/ |
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virtual void begin() = 0; |
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/**
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* @brief A method to be called on every main loop iteration. |
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* Used for tasks like checking for incoming data. |
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*/ |
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virtual void loop() = 0; |
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/**
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* @brief A callback that is triggered when the mesh transmits a packet. |
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* The bridge can use this to forward the packet. |
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* |
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* @param packet The packet that was transmitted. |
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*/ |
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virtual void onPacketTransmitted(mesh::Packet* packet) = 0; |
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/**
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* @brief Processes a received packet from the bridge's medium. |
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*/ |
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virtual void onPacketReceived() = 0; |
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}; |
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#include "SerialBridge.h" |
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#include <HardwareSerial.h> |
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#ifdef BRIDGE_OVER_SERIAL |
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#define SERIAL_PKT_MAGIC 0xcafe |
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struct SerialPacket { |
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uint16_t magic, len, crc; |
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uint8_t payload[MAX_TRANS_UNIT]; |
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SerialPacket() : magic(SERIAL_PKT_MAGIC), len(0), crc(0) {} |
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}; |
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// Fletcher-16
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// https://en.wikipedia.org/wiki/Fletcher%27s_checksum
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inline static uint16_t fletcher16(const uint8_t *bytes, const size_t len) { |
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uint8_t sum1 = 0, sum2 = 0; |
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for (size_t i = 0; i < len; i++) { |
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sum1 = (sum1 + bytes[i]) % 255; |
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sum2 = (sum2 + sum1) % 255; |
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} |
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return (sum2 << 8) | sum1; |
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}; |
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SerialBridge::SerialBridge(Stream& serial, mesh::PacketManager* mgr) : _serial(&serial), _mgr(mgr) {} |
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void SerialBridge::begin() { |
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#if defined(ESP32) |
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((HardwareSerial*)_serial)->setPins(BRIDGE_OVER_SERIAL_RX, BRIDGE_OVER_SERIAL_TX); |
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#elif defined(RP2040_PLATFORM) |
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((HardwareSerial*)_serial)->setRX(BRIDGE_OVER_SERIAL_RX); |
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((HardwareSerial*)_serial)->setTX(BRIDGE_OVER_SERIAL_TX); |
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#elif defined(STM32_PLATFORM) |
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((HardwareSerial*)_serial)->setRx(BRIDGE_OVER_SERIAL_RX); |
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((HardwareSerial*)_serial)->setTx(BRIDGE_OVER_SERIAL_TX); |
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#else |
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#error SerialBridge was not tested on the current platform |
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#endif |
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((HardwareSerial*)_serial)->begin(115200); |
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} |
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void SerialBridge::onPacketTransmitted(mesh::Packet* packet) { |
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SerialPacket spkt; |
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spkt.len = packet->writeTo(spkt.payload); |
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spkt.crc = fletcher16(spkt.payload, spkt.len); |
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_serial->write((uint8_t *)&spkt, sizeof(SerialPacket)); |
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} |
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void SerialBridge::loop() { |
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while (_serial->available()) { |
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onPacketReceived(); |
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} |
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} |
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void SerialBridge::onPacketReceived() { |
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static constexpr uint16_t size = sizeof(SerialPacket) + 1; |
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static uint8_t buffer[size]; |
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static uint16_t tail = 0; |
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buffer[tail] = (uint8_t)_serial->read(); |
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tail = (tail + 1) % size; |
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// Check for complete packet by looking back to where the magic number should be
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const uint16_t head = (tail - sizeof(SerialPacket) + size) % size; |
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if ((buffer[head] | (buffer[(head + 1) % size] << 8)) != SERIAL_PKT_MAGIC) { |
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return; |
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} |
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uint8_t bytes[MAX_TRANS_UNIT]; |
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const uint16_t len = buffer[(head + 2) % size] | (buffer[(head + 3) % size] << 8); |
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if (len == 0 || len > sizeof(bytes)) { |
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return; |
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} |
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for (size_t i = 0; i < len; i++) { |
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bytes[i] = buffer[(head + 6 + i) % size]; |
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} |
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const uint16_t crc = buffer[(head + 4) % size] | (buffer[(head + 5) % size] << 8); |
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const uint16_t f16 = fletcher16(bytes, len); |
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if ((f16 != crc)) { |
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return; |
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} |
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mesh::Packet *new_pkt = _mgr->allocNew(); |
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if (new_pkt == NULL) { |
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return; |
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} |
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new_pkt->readFrom(bytes, len); |
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_mgr->queueInbound(new_pkt, 0); |
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} |
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#endif |
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@ -0,0 +1,30 @@ |
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#pragma once |
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#include "helpers/AbstractBridge.h" |
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#include <Stream.h> |
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#ifdef BRIDGE_OVER_SERIAL |
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/**
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* @brief A bridge implementation that uses a serial port to connect two mesh networks. |
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*/ |
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class SerialBridge : public AbstractBridge { |
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public: |
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/**
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* @brief Construct a new Serial Bridge object |
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* |
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* @param serial The serial port to use for the bridge. |
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* @param mgr A pointer to the packet manager. |
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*/ |
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SerialBridge(Stream& serial, mesh::PacketManager* mgr); |
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void begin() override; |
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void loop() override; |
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void onPacketTransmitted(mesh::Packet* packet) override; |
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void onPacketReceived() override; |
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private: |
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Stream* _serial; |
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mesh::PacketManager* _mgr; |
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}; |
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#endif |
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