IsoTp: allow custom padding byte

Author: dron0gus

firmware/controllers/can/isotp/isotp.cpp

@@ -38,7 +38,10 @@ int IsoTpBase::sendFrame(const IsoTpFrameHeader &header, const uint8_t *data, in
 
 	int dlc = 8;
 	CanTxMessage txmsg(CanCategory::SERIAL, txFrameId, dlc, busIndex, IS_EXT_RANGE_ID(txFrameId));
-
+	// fill message with padding byte
+	for (int i = isoHeaderByteIndex; i < 8; i++) {
+		txmsg[i] = paddingByte;
+	}
 	// fill the frame data according to the CAN-TP protocol (ISO 15765-2)
 	txmsg[isoHeaderByteIndex] = (uint8_t)((header.frameType & 0xf) << 4);
 	switch (header.frameType) {

firmware/controllers/can/isotp/isotp.h

@@ -113,6 +113,10 @@ class IsoTpBase {
 	// but some vendors add some specific data in first CAN byte
 	size_t isoHeaderByteIndex = 0;
 
+	// default padding byte
+	// Normally a "0xA" is used as padding since it will produce no stuffing bits on the CAN.
+	uint8_t paddingByte = 0x0A;
+
 	ICanTransmitter *txTransport;
 
 	size_t busIndex;