Rename SerialBridge to RS232Bridge

src/helpers/bridges/RS232Bridge.cpp

@@ -0,0 +1,123 @@
+#include "RS232Bridge.h"
+#include <HardwareSerial.h>
+#include <RTClib.h>
+
+#ifdef WITH_RS232_BRIDGE
+
+// Fletcher-16
+// https://en.wikipedia.org/wiki/Fletcher%27s_checksum
+inline static uint16_t fletcher16(const uint8_t *bytes, const size_t len) {
+  uint8_t sum1 = 0, sum2 = 0;
+
+  for (size_t i = 0; i < len; i++) {
+    sum1 = (sum1 + bytes[i]) % 255;
+    sum2 = (sum2 + sum1) % 255;
+  }
+
+  return (sum2 << 8) | sum1;
+};
+
+const char* RS232Bridge::getLogDateTime() {
+  static char tmp[32];
+  uint32_t now = _rtc->getCurrentTime();
+  DateTime dt = DateTime(now);
+  sprintf(tmp, "%02d:%02d:%02d - %d/%d/%d U", dt.hour(), dt.minute(), dt.second(), dt.day(), dt.month(), dt.year());
+  return tmp;
+}
+
+RS232Bridge::RS232Bridge(Stream& serial, mesh::PacketManager* mgr, mesh::RTCClock* rtc) : _serial(&serial), _mgr(mgr), _rtc(rtc) {}
+
+void RS232Bridge::begin() {
+#if !defined(WITH_RS232_BRIDGE_RX) || !defined(WITH_RS232_BRIDGE_TX)
+#error "WITH_RS232_BRIDGE_RX and WITH_RS232_BRIDGE_TX must be defined"
+#endif
+
+#if defined(ESP32)
+  ((HardwareSerial *)_serial)->setPins(WITH_RS232_BRIDGE_RX, WITH_RS232_BRIDGE_TX);
+#elif defined(NRF52_PLATFORM)
+  ((HardwareSerial *)_serial)->setPins(WITH_RS232_BRIDGE_RX, WITH_RS232_BRIDGE_TX);
+#elif defined(RP2040_PLATFORM)
+  ((SerialUART *)_serial)->setRX(WITH_RS232_BRIDGE_RX);
+  ((SerialUART *)_serial)->setTX(WITH_RS232_BRIDGE_TX);
+#elif defined(STM32_PLATFORM)
+  ((HardwareSerial *)_serial)->setRx(WITH_RS232_BRIDGE_RX);
+  ((HardwareSerial *)_serial)->setTx(WITH_RS232_BRIDGE_TX);
+#else
+#error RS232Bridge was not tested on the current platform
+#endif
+  ((HardwareSerial*)_serial)->begin(115200);
+}
+
+void RS232Bridge::onPacketTransmitted(mesh::Packet* packet) {
+  if (!_seen_packets.hasSeen(packet)) {
+    uint8_t buffer[MAX_SERIAL_PACKET_SIZE];
+    uint16_t len = packet->writeTo(buffer + 4);
+
+    buffer[0] = (SERIAL_PKT_MAGIC >> 8) & 0xFF;
+    buffer[1] = SERIAL_PKT_MAGIC & 0xFF;
+    buffer[2] = (len >> 8) & 0xFF;
+    buffer[3] = len & 0xFF;
+
+    uint16_t checksum = fletcher16(buffer + 4, len);
+    buffer[4 + len] = (checksum >> 8) & 0xFF;
+    buffer[5 + len] = checksum & 0xFF;
+
+    _serial->write(buffer, len + SERIAL_OVERHEAD);
+
+#if MESH_PACKET_LOGGING
+    Serial.printf("%s: BRIDGE: TX, len=%d crc=0x%04x\n", getLogDateTime(), len, checksum);
+#endif
+  }
+}
+
+void RS232Bridge::loop() {
+  while (_serial->available()) {
+    uint8_t b = _serial->read();
+
+    if (_rx_buffer_pos < 2) {
+      // Waiting for magic word
+      if ((_rx_buffer_pos == 0 && b == ((SERIAL_PKT_MAGIC >> 8) & 0xFF)) ||
+          (_rx_buffer_pos == 1 && b == (SERIAL_PKT_MAGIC & 0xFF))) {
+        _rx_buffer[_rx_buffer_pos++] = b;
+      } else {
+        _rx_buffer_pos = 0;
+      }
+    } else {
+      // Reading length, payload, and checksum
+      _rx_buffer[_rx_buffer_pos++] = b;
+
+      if (_rx_buffer_pos >= 4) {
+        uint16_t len = (_rx_buffer[2] << 8) | _rx_buffer[3];
+        if (len > (MAX_TRANS_UNIT + 1)) {
+          _rx_buffer_pos = 0; // Invalid length, reset
+          return;
+        }
+
+        if (_rx_buffer_pos == len + SERIAL_OVERHEAD) { // Full packet received
+          uint16_t checksum = (_rx_buffer[4 + len] << 8) | _rx_buffer[5 + len];
+          if (checksum == fletcher16(_rx_buffer + 4, len)) {
+#if MESH_PACKET_LOGGING
+            Serial.printf("%s: BRIDGE: RX, len=%d crc=0x%04x\n", getLogDateTime(), len, checksum);
+#endif
+            mesh::Packet* pkt = _mgr->allocNew();
+            if (pkt) {
+              pkt->readFrom(_rx_buffer + 4, len);
+              onPacketReceived(pkt);
+            }
+          }
+          _rx_buffer_pos = 0; // Reset for next packet
+        }
+      }
+    }
+  }
+}
+
+void RS232Bridge::onPacketReceived(mesh::Packet* packet) {
+  if (!_seen_packets.hasSeen(packet)) {
+    _mgr->queueInbound(packet, 0);
+  } else {
+    _mgr->free(packet);
+  }
+}
+
+#endif

src/helpers/bridges/RS232Bridge.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include "helpers/AbstractBridge.h"
+#include "helpers/SimpleMeshTables.h"
+#include <Stream.h>
+
+#ifdef WITH_RS232_BRIDGE
+
+/**
+ * @brief A bridge implementation that uses a serial port to connect two mesh networks.
+ */
+class RS232Bridge : public AbstractBridge {
+public:
+  /**
+   * @brief Construct a new Serial Bridge object
+   * 
+   * @param serial The serial port to use for the bridge.
+   * @param mgr A pointer to the packet manager.
+   * @param rtc A pointer to the RTC clock.
+   */
+  RS232Bridge(Stream& serial, mesh::PacketManager* mgr, mesh::RTCClock* rtc);
+  void begin() override;
+  void loop() override;
+  void onPacketTransmitted(mesh::Packet* packet) override;
+  void onPacketReceived(mesh::Packet* packet) override;
+
+private:
+  const char* getLogDateTime();
+  /**
+   * @brief The 2-byte magic word used to signify the start of a packet.
+   */
+  static constexpr uint16_t SERIAL_PKT_MAGIC = 0xCAFE;
+
+  /**
+   * @brief The total overhead of the serial protocol in bytes.
+   *        [MAGIC_WORD (2 bytes)] [LENGTH (2 bytes)] [PAYLOAD (variable)] [CHECKSUM (2 bytes)]
+   */
+  static constexpr uint16_t SERIAL_OVERHEAD = 6;
+
+  /**
+   * @brief The maximum size of a packet on the serial line.
+   *
+   * This is calculated as the sum of:
+   * - 1 byte for the packet header (from mesh::Packet)
+   * - 4 bytes for transport codes (from mesh::Packet)
+   * - 1 byte for the path length (from mesh::Packet)
+   * - MAX_PATH_SIZE for the path itself (from MeshCore.h)
+   * - MAX_PACKET_PAYLOAD for the payload (from MeshCore.h)
+   * - SERIAL_OVERHEAD for the serial framing
+   */
+  static constexpr uint16_t MAX_SERIAL_PACKET_SIZE = (MAX_TRANS_UNIT + 1) + SERIAL_OVERHEAD;
+
+  Stream* _serial;
+  mesh::PacketManager* _mgr;
+  mesh::RTCClock* _rtc;
+  SimpleMeshTables _seen_packets;
+  uint8_t _rx_buffer[MAX_SERIAL_PACKET_SIZE]; // Buffer for serial data
+  uint16_t _rx_buffer_pos = 0;
+};
+
+#endif