Initial commit

src/lora_transport.cpp

@@ -0,0 +1,102 @@
+#include "lora_transport.h"
+#include <LoRa.h>
+#include <SPI.h>
+
+static uint16_t crc16_ccitt(const uint8_t *data, size_t len) {
+  uint16_t crc = 0xFFFF;
+  for (size_t i = 0; i < len; ++i) {
+    crc ^= static_cast<uint16_t>(data[i]) << 8;
+    for (uint8_t b = 0; b < 8; ++b) {
+      if (crc & 0x8000) {
+        crc = (crc << 1) ^ 0x1021;
+      } else {
+        crc <<= 1;
+      }
+    }
+  }
+  return crc;
+}
+
+void lora_init() {
+  SPI.begin(PIN_LORA_SCK, PIN_LORA_MISO, PIN_LORA_MOSI, PIN_LORA_NSS);
+  LoRa.setPins(PIN_LORA_NSS, PIN_LORA_RST, PIN_LORA_DIO0);
+  LoRa.begin(LORA_FREQUENCY);
+  LoRa.setSpreadingFactor(LORA_SPREADING_FACTOR);
+  LoRa.setSignalBandwidth(LORA_BANDWIDTH);
+  LoRa.setCodingRate4(LORA_CODING_RATE);
+  LoRa.enableCrc();
+  LoRa.setSyncWord(LORA_SYNC_WORD);
+}
+
+bool lora_send(const LoraPacket &pkt) {
+  uint8_t buffer[5 + LORA_MAX_PAYLOAD + 2];
+  size_t idx = 0;
+  buffer[idx++] = pkt.protocol_version;
+  buffer[idx++] = static_cast<uint8_t>(pkt.role);
+  buffer[idx++] = static_cast<uint8_t>(pkt.device_id_short >> 8);
+  buffer[idx++] = static_cast<uint8_t>(pkt.device_id_short & 0xFF);
+  buffer[idx++] = static_cast<uint8_t>(pkt.payload_type);
+
+  if (pkt.payload_len > LORA_MAX_PAYLOAD) {
+    return false;
+  }
+
+  memcpy(&buffer[idx], pkt.payload, pkt.payload_len);
+  idx += pkt.payload_len;
+
+  uint16_t crc = crc16_ccitt(buffer, idx);
+  buffer[idx++] = static_cast<uint8_t>(crc >> 8);
+  buffer[idx++] = static_cast<uint8_t>(crc & 0xFF);
+
+  LoRa.beginPacket();
+  LoRa.write(buffer, idx);
+  LoRa.endPacket();
+  return true;
+}
+
+bool lora_receive(LoraPacket &pkt, uint32_t timeout_ms) {
+  uint32_t start = millis();
+  while (true) {
+    int packet_size = LoRa.parsePacket();
+    if (packet_size > 0) {
+      if (packet_size < 7) {
+        while (LoRa.available()) {
+          LoRa.read();
+        }
+        return false;
+      }
+
+      uint8_t buffer[5 + LORA_MAX_PAYLOAD + 2];
+      size_t len = 0;
+      while (LoRa.available() && len < sizeof(buffer)) {
+        buffer[len++] = LoRa.read();
+      }
+
+      if (len < 7) {
+        return false;
+      }
+
+      uint16_t crc_calc = crc16_ccitt(buffer, len - 2);
+      uint16_t crc_rx = static_cast<uint16_t>(buffer[len - 2] << 8) | buffer[len - 1];
+      if (crc_calc != crc_rx) {
+        return false;
+      }
+
+      pkt.protocol_version = buffer[0];
+      pkt.role = static_cast<DeviceRole>(buffer[1]);
+      pkt.device_id_short = static_cast<uint16_t>(buffer[2] << 8) | buffer[3];
+      pkt.payload_type = static_cast<PayloadType>(buffer[4]);
+      pkt.payload_len = len - 7;
+      if (pkt.payload_len > LORA_MAX_PAYLOAD) {
+        return false;
+      }
+      memcpy(pkt.payload, &buffer[5], pkt.payload_len);
+      return true;
+    }
+
+    if (timeout_ms == 0 || millis() - start >= timeout_ms) {
+      return false;
+    }
+    delay(5);
+  }
+}