Update to the latest M17 specification.

M17Defines.h

@@ -26,10 +26,13 @@ const unsigned int M17_FRAME_LENGTH_BYTES   = M17_FRAME_LENGTH_BITS / 8U;
 
 const unsigned int M17_SYNC_LENGTH_BITS    = 16U;
 
-const uint8_t M17_SYNC_BYTES[]      = {0x32U, 0x43U};
+const uint8_t M17_HEADER_SYNC_BYTES[]      = {0x5DU, 0xDDU};
+const uint8_t M17_DATA_SYNC_BYTES[]        = {0xDDU, 0xDDU};
+
 const uint8_t M17_SYNC_BYTES_LENGTH = 2U;
 
-const uint16_t M17_SYNC_BITS      = 0x3243U;
+const uint16_t M17_HEADER_SYNC_BITS = 0x5DDDU;
+const uint16_t M17_DATA_SYNC_BITS   = 0xDDDDU;
 
 #endif
 

M17RX.cpp

@@ -52,10 +52,17 @@ void CM17RX::reset()
 
 void CM17RX::databit(bool bit)
 {
-  if (m_state == M17RXS_NONE)
+  switch (m_state)  {
+    case M17RXS_NONE:
       processNone(bit);
-  else
+      break;
+    case M17RXS_HEADER:
+      processHeader(bit);
+      break;
+    default:
       processData(bit);
+      break;
+  }
 }
 
 void CM17RX::processNone(bool bit)
@@ -64,11 +71,24 @@ void CM17RX::processNone(bool bit)
   if (bit)
     m_bitBuffer |= 0x01U;
 
-  // Fuzzy matching of the data sync bit sequence
+  // Fuzzy matching of the header sync bit sequence
-  if (countBits16(m_bitBuffer ^ M17_SYNC_BITS) <= MAX_SYNC_BIT_START_ERRS) {
+  if (countBits16(m_bitBuffer ^ M17_HEADER_SYNC_BITS) <= MAX_SYNC_BIT_START_ERRS) {
-    DEBUG1("M17RX: sync found in None");
+    DEBUG1("M17RX: header sync found in None");
     for (uint8_t i = 0U; i < M17_SYNC_BYTES_LENGTH; i++)
-      m_buffer[i] = M17_SYNC_BYTES[i];
+      m_buffer[i] = M17_HEADER_SYNC_BYTES[i];
+
+    m_lostCount = MAX_SYNC_FRAMES;
+    m_bufferPtr = M17_SYNC_LENGTH_BITS;
+    m_state     = M17RXS_HEADER;
+
+    io.setDecode(true);
+  }
+
+  // Fuzzy matching of the data sync bit sequence
+  if (countBits16(m_bitBuffer ^ M17_DATA_SYNC_BITS) <= MAX_SYNC_BIT_START_ERRS) {
+    DEBUG1("M17RX: data sync found in None");
+    for (uint8_t i = 0U; i < M17_SYNC_BYTES_LENGTH; i++)
+      m_buffer[i] = M17_DATA_SYNC_BYTES[i];
 
     m_lostCount = MAX_SYNC_FRAMES;
     m_bufferPtr = M17_SYNC_LENGTH_BITS;
@@ -76,7 +96,43 @@ void CM17RX::processNone(bool bit)
 
     io.setDecode(true);
   }
+}
 
+void CM17RX::processHeader(bool bit)
+{
+  m_bitBuffer <<= 1;
+  if (bit)
+    m_bitBuffer |= 0x01U;
+
+  WRITE_BIT1(m_buffer, m_bufferPtr, bit);
+
+  m_bufferPtr++;
+  if (m_bufferPtr > M17_FRAME_LENGTH_BITS)
+    reset();
+
+  // Only search for a sync in the right place +-2 symbols
+  if (m_bufferPtr >= (M17_SYNC_LENGTH_BITS - 2U) && m_bufferPtr <= (M17_SYNC_LENGTH_BITS + 2U)) {
+    // Fuzzy matching of the data sync bit sequence
+    if (countBits16(m_bitBuffer ^ M17_HEADER_SYNC_BITS) <= MAX_SYNC_BIT_RUN_ERRS) {
+      DEBUG2("M17RX: found header sync in Data, pos", m_bufferPtr - M17_SYNC_LENGTH_BITS);
+      m_lostCount = MAX_SYNC_FRAMES;
+      m_bufferPtr = M17_SYNC_LENGTH_BITS;
+    }
+  }
+
+  // Send a data frame to the host if the required number of bits have been received
+  if (m_bufferPtr == M17_FRAME_LENGTH_BITS) {
+    m_lostCount--;
+
+    // Write data to host
+    m_outBuffer[0U] = 0x01U;
+    writeRSSIHeader(m_outBuffer);
+
+    // Start the next frame
+    ::memset(m_outBuffer, 0x00U, M17_FRAME_LENGTH_BYTES + 3U);
+    m_state     = M17RXS_DATA;
+    m_bufferPtr = 0U;
+  }
 }
 
 void CM17RX::processData(bool bit)
@@ -94,8 +150,8 @@ void CM17RX::processData(bool bit)
   // Only search for a sync in the right place +-2 symbols
   if (m_bufferPtr >= (M17_SYNC_LENGTH_BITS - 2U) && m_bufferPtr <= (M17_SYNC_LENGTH_BITS + 2U)) {
     // Fuzzy matching of the data sync bit sequence
-    if (countBits16(m_bitBuffer ^ M17_SYNC_BITS) <= MAX_SYNC_BIT_RUN_ERRS) {
+    if (countBits16(m_bitBuffer ^ M17_DATA_SYNC_BITS) <= MAX_SYNC_BIT_RUN_ERRS) {
-      DEBUG2("M17RX: found sync in Data, pos", m_bufferPtr - M17_SYNC_LENGTH_BITS);
+      DEBUG2("M17RX: found data sync in Data, pos", m_bufferPtr - M17_SYNC_LENGTH_BITS);
       m_lostCount = MAX_SYNC_FRAMES;
       m_bufferPtr = M17_SYNC_LENGTH_BITS;
     }
@@ -122,6 +178,20 @@ void CM17RX::processData(bool bit)
   }
 }
 
+void CM17RX::writeRSSIHeader(uint8_t* data)
+{
+#if defined(SEND_RSSI_DATA)
+  uint16_t rssi = io.readRSSI();
+
+  data[49U] = (rssi >> 8) & 0xFFU;
+  data[50U] = (rssi >> 0) & 0xFFU;
+
+  serial.writeM17Header(data, M17_FRAME_LENGTH_BYTES + 3U);
+#else
+  serial.writeM17Header(data, M17_FRAME_LENGTH_BYTES + 1U);
+#endif
+}
+
 void CM17RX::writeRSSIData(uint8_t* data)
 {
 #if defined(SEND_RSSI_DATA)

M17RX.h

@@ -24,6 +24,7 @@
 
 enum M17RX_STATE {
   M17RXS_NONE,
+  M17RXS_HEADER,
   M17RXS_DATA
 };
 
@@ -44,7 +45,9 @@ private:
   uint16_t    m_lostCount;
 
   void processNone(bool bit);
+  void processHeader(bool bit);
   void processData(bool bit);
+  void writeRSSIHeader(uint8_t* data);
   void writeRSSIData(uint8_t* data);
 };
 

SerialPort.cpp

@@ -60,8 +60,9 @@ const uint8_t MMDVM_P25_LOST     = 0x32U;
 const uint8_t MMDVM_NXDN_DATA    = 0x40U;
 const uint8_t MMDVM_NXDN_LOST    = 0x41U;
 
-const uint8_t MMDVM_M17_DATA     = 0x45U;
+const uint8_t MMDVM_M17_HEADER   = 0x45U;
-const uint8_t MMDVM_M17_LOST     = 0x46U;
+const uint8_t MMDVM_M17_DATA     = 0x46U;
+const uint8_t MMDVM_M17_LOST     = 0x47U;
 
 const uint8_t MMDVM_POCSAG_DATA  = 0x50U;
 
@@ -864,6 +865,20 @@ void CSerialPort::process()
             }
             break;
 
+          case MMDVM_M17_HEADER:
+            if (m_m17Enable) {
+              if (m_modemState == STATE_IDLE || m_modemState == STATE_M17)
+                err = m17TX.writeData(m_buffer + 3U, m_len - 3U);
+            }
+            if (err == 0U) {
+              if (m_modemState == STATE_IDLE)
+                setMode(STATE_M17);
+            } else {
+              DEBUG2("Received invalid M17 header", err);
+              sendNAK(err);
+            }
+            break;
+
           case MMDVM_M17_DATA:
             if (m_m17Enable) {
               if (m_modemState == STATE_IDLE || m_modemState == STATE_M17)
@@ -1233,6 +1248,29 @@ void CSerialPort::writeNXDNLost()
   writeInt(1U, reply, 3);
 }
 
+void CSerialPort::writeM17Header(const uint8_t* data, uint8_t length)
+{
+  if (m_modemState != STATE_M17 && m_modemState != STATE_IDLE)
+    return;
+
+  if (!m_m17Enable)
+    return;
+
+  uint8_t reply[130U];
+
+  reply[0U] = MMDVM_FRAME_START;
+  reply[1U] = 0U;
+  reply[2U] = MMDVM_M17_HEADER;
+
+  uint8_t count = 3U;
+  for (uint8_t i = 0U; i < length; i++, count++)
+    reply[count] = data[i];
+
+  reply[1U] = count;
+
+  writeInt(1U, reply, count);
+}
+
 void CSerialPort::writeM17Data(const uint8_t* data, uint8_t length)
 {
   if (m_modemState != STATE_M17 && m_modemState != STATE_IDLE)

SerialPort.h

@@ -52,6 +52,7 @@ public:
   void writeNXDNData(const uint8_t* data, uint8_t length);
   void writeNXDNLost();
 
+  void writeM17Header(const uint8_t* data, uint8_t length);
   void writeM17Data(const uint8_t* data, uint8_t length);
   void writeM17Lost();
 

version.h

@@ -25,7 +25,7 @@
 #define VER_MAJOR       "1"
 #define VER_MINOR       "5"
 #define VER_REV         "2"
-#define VERSION_DATE    "20201111"
+#define VERSION_DATE    "20201126"
 
 #if defined(ZUMSPOT_ADF7021)
 #define BOARD_INFO      "ZUMspot"