[SX127x] Fixed direct mode inactive until first packet is received (#337)

src/modules/SX127x/SX127x.cpp

@@ -92,7 +92,7 @@ int16_t SX127x::beginFSK(uint8_t chipVersion, float br, float freqDev, float rxB
   state = SX127x::setAFCBandwidth(rxBw);
   RADIOLIB_ASSERT(state);
 
-  //sets AFC&AGC trigger to RSSI and preamble detect
+  // sets AFC&AGC trigger to RSSI and preamble detect
   state = SX127x::setAFCAGCTrigger(SX127X_RX_TRIGGER_BOTH);
   RADIOLIB_ASSERT(state);
 
@@ -359,6 +359,10 @@ int16_t SX127x::directMode() {
   state = _mod->SPIsetRegValue(SX127X_REG_DIO_MAPPING_1, SX127X_DIO1_CONT_DCLK | SX127X_DIO2_CONT_DATA, 5, 2);
   RADIOLIB_ASSERT(state);
 
+  // enable receiver startup without preamble or RSSI
+  state = SX127x::setAFCAGCTrigger(SX127X_RX_TRIGGER_NONE);
+  RADIOLIB_ASSERT(state);
+
   // set continuous mode
   return(_mod->SPIsetRegValue(SX127X_REG_PACKET_CONFIG_2, SX127X_DATA_MODE_CONTINUOUS, 6, 6));
 }