[SX126x] Added support for AFSK transmission

src/modules/SX126x/SX126x.cpp

@@ -321,6 +321,63 @@ int16_t SX126x::receiveDirect() {
   return(RADIOLIB_ERR_UNKNOWN);
 }
 
+int16_t SX126x::directMode() {
+  // check modem
+  if(getPacketType() != RADIOLIB_SX126X_PACKET_TYPE_GFSK) {
+    return(RADIOLIB_ERR_WRONG_MODEM);
+  }
+
+  // set mode to standby
+  int16_t state = standby();
+  RADIOLIB_ASSERT(state);
+
+  // disable DIO2 RF switch
+  state = setDio2AsRfSwitch(false);
+  RADIOLIB_ASSERT(state);
+
+  // set DIO2 to clock output and DIO3 to data input
+  // this is done exclusively by writing magic values to even more magic registers
+  uint8_t val = 0;
+
+  state = readRegister(RADIOLIB_SX126X_REG_TX_BITBANG_ENABLE_1, &val, 1);
+  RADIOLIB_ASSERT(state);
+  val &= ~(0x07 << 4);
+  val |= (0x01 << 4);
+  state = writeRegister(RADIOLIB_SX126X_REG_TX_BITBANG_ENABLE_1, &val, 1);
+  RADIOLIB_ASSERT(state);
+  
+  state = readRegister(RADIOLIB_SX126X_REG_TX_BITBANG_ENABLE_0, &val, 1);
+  RADIOLIB_ASSERT(state);
+  val &= ~(0x0F << 0);
+  val |= (0x0C << 0);
+  state = writeRegister(RADIOLIB_SX126X_REG_TX_BITBANG_ENABLE_0, &val, 1);
+  RADIOLIB_ASSERT(state);
+  
+  state = readRegister(RADIOLIB_SX126X_REG_DIOX_OUT_ENABLE, &val, 1);
+  RADIOLIB_ASSERT(state);
+  val &= ~(0x01 << 3);
+  val |= (0x01 << 3);
+  state = writeRegister(RADIOLIB_SX126X_REG_DIOX_OUT_ENABLE, &val, 1);
+  RADIOLIB_ASSERT(state);
+  
+  state = readRegister(RADIOLIB_SX126X_REG_DIOX_IN_ENABLE, &val, 1);
+  RADIOLIB_ASSERT(state);
+  val &= ~(0x01 << 3);
+  val |= (0x01 << 3);
+  state = writeRegister(RADIOLIB_SX126X_REG_DIOX_IN_ENABLE, &val, 1);
+  RADIOLIB_ASSERT(state);
+
+  // enable TxDone interrupt
+  state = setDioIrqParams(RADIOLIB_SX126X_IRQ_TX_DONE, RADIOLIB_SX126X_IRQ_TX_DONE);
+  RADIOLIB_ASSERT(state);
+
+  // set preamble length to the maximum to prevent SX126x from exiting Tx mode for a while
+  state = setPreambleLength(0xFFFF);
+  RADIOLIB_ASSERT(state);
+
+  return(state);
+}
+
 int16_t SX126x::scanChannel(uint8_t symbolNum, uint8_t detPeak, uint8_t detMin) {
   // set mode to CAD
   int state = startChannelScan(symbolNum, detPeak, detMin);

src/modules/SX126x/SX126x.h

@@ -83,8 +83,11 @@
 #define RADIOLIB_SX126X_REG_DIOX_IN_ENABLE                     0x0583
 #define RADIOLIB_SX126X_REG_DIOX_PULL_UP_CTRL                  0x0584
 #define RADIOLIB_SX126X_REG_DIOX_PULL_DOWN_CTRL                0x0585
+#define RADIOLIB_SX126X_REG_TX_BITBANG_ENABLE_0                0x0587
+#define RADIOLIB_SX126X_REG_TX_BITBANG_ENABLE_1                0x0680
 #define RADIOLIB_SX126X_REG_WHITENING_INITIAL_MSB              0x06B8
 #define RADIOLIB_SX126X_REG_WHITENING_INITIAL_LSB              0x06B9
+#define RADIOLIB_SX126X_REG_RX_TX_PLD_LEN                      0x06BB
 #define RADIOLIB_SX126X_REG_CRC_INITIAL_MSB                    0x06BC
 #define RADIOLIB_SX126X_REG_CRC_INITIAL_LSB                    0x06BD
 #define RADIOLIB_SX126X_REG_CRC_POLYNOMIAL_MSB                 0x06BE
@@ -102,6 +105,7 @@
 #define RADIOLIB_SX126X_REG_IQ_CONFIG                          0x0736
 #define RADIOLIB_SX126X_REG_LORA_SYNC_WORD_MSB                 0x0740
 #define RADIOLIB_SX126X_REG_LORA_SYNC_WORD_LSB                 0x0741
+#define RADIOLIB_SX126X_REG_RX_ADDR_PTR                        0x0803
 #define RADIOLIB_SX126X_REG_RANDOM_NUMBER_0                    0x0819
 #define RADIOLIB_SX126X_REG_RANDOM_NUMBER_1                    0x081A
 #define RADIOLIB_SX126X_REG_RANDOM_NUMBER_2                    0x081B
@@ -1013,6 +1017,7 @@ class SX126x: public PhysicalLayer {
     int16_t setFrequencyRaw(float freq);
     int16_t setPacketMode(uint8_t mode, uint8_t len);
     int16_t setHeaderType(uint8_t headerType, size_t len = 0xFF);
+    int16_t directMode();
 
     // fixes to errata
     int16_t fixSensitivity();