TX happening in single SPI transaction

crossbow.ino

@@ -1,5 +1,5 @@
-// #define DEVICE_MODE_TX
-#define DEVICE_MODE_RX
+#define DEVICE_MODE_TX
+// #define DEVICE_MODE_RX
 
 // #define FEATURE_TX_OLED
 #define FORCE_TX_WITHOUT_INPUT
@@ -60,6 +60,8 @@ RxDeviceState_t rxDeviceState = {};
 TxDeviceState_t txDeviceState = {};
 volatile RadioState_t radioState;
 
+uint8_t tmpBuffer[MAX_PACKET_SIZE];
+
 uint8_t getRadioRssi(void)
 {
     return 164 - constrain(LoRa.packetRssi() * -1, 0, 164);
@@ -263,8 +265,6 @@ void loop(void)
 {
 
     if (radioState.bytesToRead != NO_DATA_TO_READ) {
-        static uint8_t tmpBuffer[20];
-
         LoRa.read(tmpBuffer, radioState.bytesToRead);
 
         for (int i = 0; i < radioState.bytesToRead; i++) {
@@ -395,8 +395,12 @@ void loop(void)
 
     if (qsp.canTransmit && transmitPayload)
     {
+        uint8_t size;
         LoRa.beginPacket();
-        qspEncodeFrame(&qsp);
+        //Prepare packet
+        qspEncodeFrame(&qsp, tmpBuffer, &size);
+        //Sent it to radio in one SPI transaction
+        LoRa.write(tmpBuffer, size);
         LoRa.endPacket();
         //After ending packet, put device into receive mode again
         LoRa.receive();

qsp.cpp

@@ -230,26 +230,27 @@ void qspDecodeIncomingFrame(
 /**
  * Encode frame is corrent format and write to hardware
  */
-void qspEncodeFrame(QspConfiguration_t *qsp) {
+void qspEncodeFrame(QspConfiguration_t *qsp, uint8_t buffer[], uint8_t *size) {
     //Zero CRC
     qsp->crc = 0;
 
-    //Write CHANNEL_ID
-    qsp->hardwareWriteFunction(CHANNEL_ID, qsp);
+    qspComputeCrc(qsp, CHANNEL_ID);
+    buffer[0] = CHANNEL_ID;
 
     //Write frame type and length
     uint8_t data = qsp->payloadLength & 0x0f;
     data |= (qsp->frameToSend << 4) & 0xf0;
-    qsp->hardwareWriteFunction(data, qsp);
+    qspComputeCrc(qsp, data);
+    buffer[1] = data;
 
-    //Write payload
     for (uint8_t i = 0; i < qsp->payloadLength; i++)
     {
-        qsp->hardwareWriteFunction(qsp->payload[i], qsp);
+        qspComputeCrc(qsp, qsp->payload[i]);
+        buffer[i + 2] = qsp->payload[i];
     }
 
-    //Finally write CRC
-    qsp->hardwareWriteFunction(qsp->crc, qsp);
+    buffer[qsp->payloadLength + 2] = qsp->crc;
+    *size = qsp->payloadLength + 3; //Total length of QSP frame
 }
 
 void encodePingPayload(QspConfiguration_t *qsp, uint32_t currentMicros) {

qsp.h

@@ -17,6 +17,6 @@ void qspDecodeIncomingFrame(
     RadioState_t *radioState
 );
 void qspClearPayload(QspConfiguration_t *qsp);
-void qspEncodeFrame(QspConfiguration_t *qsp);
+void qspEncodeFrame(QspConfiguration_t *qsp, uint8_t buffer[], uint8_t *size);
 
 void encodePingPayload(QspConfiguration_t *qsp, uint32_t currentMicros);