Add support for returning TX backpack version

lib/MSP/msp.cpp

@@ -97,7 +97,10 @@ MSP::processReceivedByte(uint8_t c)
                 m_packet.flags = header->flags;
                 // reset the offset iterator for re-use in payload below
                 m_offset = 0;
-                m_inputState = MSP_PAYLOAD_V2_NATIVE;
+                if (m_packet.payloadSize == 0)
+                    m_inputState = MSP_CHECKSUM_V2_NATIVE;
+                else
+                    m_inputState = MSP_PAYLOAD_V2_NATIVE;
             }
             break;
 

lib/MSP/msp.h

@@ -2,11 +2,7 @@
 
 #include <Arduino.h>
 
-// TODO: MSP_PORT_INBUF_SIZE should be changed to
-// dynamically allocate array length based on the payload size
-// Hardcoding payload size to 8 bytes for now, since MSP is
-// limited to a 4 byte payload on the BF side
-#define MSP_PORT_INBUF_SIZE 8
+#define MSP_PORT_INBUF_SIZE 32
 
 #define CHECK_PACKET_PARSING() \
   if (packet->readError) {\

lib/MSP/msptypes.h

@@ -16,6 +16,9 @@
 #define MSP_ELRS_REQU_VTX_PKT                   0x0B
 #define MSP_ELRS_SET_TX_BACKPACK_WIFI_MODE      0x0C
 #define MSP_ELRS_SET_VRX_BACKPACK_WIFI_MODE     0x0D
+#define MSP_ELRS_SET_RX_WIFI_MODE               0x0E
+#define MSP_ELRS_SET_RX_LOAN_MODE               0x0F
+#define MSP_ELRS_GET_BACKPACK_VERSION           0x10
 
 // CRSF encapsulated msp defines
 #define ENCAPSULATED_MSP_PAYLOAD_SIZE           4

src/Tx_main.cpp

@@ -23,6 +23,8 @@ uint8_t broadcastAddress[6] = {0, 0, 0, 0, 0, 0};
 #endif
 uint8_t bindingAddress[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
 
+const uint8_t version[] = {LATEST_VERSION};
+
 connectionState_e connectionState = starting;
 unsigned long rebootTime = 0;
 
@@ -98,6 +100,17 @@ void OnDataRecv(uint8_t * mac_addr, uint8_t *data, uint8_t data_len)
   blinkLED();
 }
 
+void SendVersionResponse()
+{
+  mspPacket_t out;
+  out.reset();
+  out.makeResponse();
+  out.function = MSP_ELRS_GET_BACKPACK_VERSION;
+  for (size_t i=0 ; i<sizeof(version) ; i++)
+    out.addByte(version[i]);
+  msp.sendPacket(&out, &Serial);
+}
+
 void ProcessMSPPacketFromTX(mspPacket_t *packet)
 {
   if (packet->function == MSP_ELRS_BIND)
@@ -134,6 +147,10 @@ void ProcessMSPPacketFromTX(mspPacket_t *packet)
     DBGLN("Processing MSP_ELRS_SET_TX_BACKPACK_WIFI_MODE...");
     RebootIntoWifi();
     break;
+  case MSP_ELRS_GET_BACKPACK_VERSION:
+    DBGLN("Processing MSP_ELRS_GET_BACKPACK_VERSION...");
+    SendVersionResponse();
+    break;
   default:
     // transparently forward MSP packets via espnow to any subscribers
     sendMSPViaEspnow(packet);