void trxWriteFrameBuffer(MacPacket packet) {
unsigned int i;
unsigned char phy_len;
Payload pld;
// Linearize contents in buffer
i = 0;
phy_len = packet->payload_length + MAC_HEADER_LENGTH + CRC_LENGTH;
frame_buffer[i++] = phy_len; //packet->payload_length + MAC_HEADER_LENGTH + CRC_LENGTH;
frame_buffer[i++] = packet->frame_ctrl.val.byte.LB;
frame_buffer[i++] = packet->frame_ctrl.val.byte.HB;
frame_buffer[i++] = packet->seq_num;
frame_buffer[i++] = packet->dest_pan_id.byte.LB;
frame_buffer[i++] = packet->dest_pan_id.byte.HB;
frame_buffer[i++] = packet->dest_addr.byte.LB;
frame_buffer[i++] = packet->dest_addr.byte.HB;
frame_buffer[i++] = packet->src_addr.byte.LB;
frame_buffer[i++] = packet->src_addr.byte.HB;
pld = macGetPayload(packet);
if(pld == NULL) { return; }
memcpy(frame_buffer + i, payToString(pld), payGetPayloadLength(pld));
spic1BeginTransaction();
spic1Transmit(TRX_CMD_FW);
spic1MassTransmit(phy_len, frame_buffer, phy_len*3); // 3*length microseconds timeout seems to work well
}
//Recieved radio packet, send over UART
void xbeeHandleRx(MacPacket packet) {
int i;
unsigned char checksum;
unsigned char pld_len = payGetPayloadLength(packet->payload);
unsigned char* pld_str = payToString(packet->payload);
unsigned char xb_frame_len = pld_len + XB_OVERHEAD_LENGTH;
WordVal src_addr = packet->src_addr;
dmaTxReady = 0;
checksum = XB_API_ID;
checksum += src_addr.byte.HB;
checksum += src_addr.byte.LB;
//CRITICAL_SECTION_START
txBufferA[0] = XB_RX_START; //Start Byte
txBufferA[1] = 0x00; //Length High Byte
txBufferA[2] = xb_frame_len; //Length Low Byte
txBufferA[3] = XB_API_ID; //API Identifier - Currently only support the RX type
txBufferA[4] = src_addr.byte.HB; //Source Address High byte
txBufferA[5] = src_addr.byte.LB; //Source Address Low Byte
txBufferA[6] = radioGetLastRSSI(); //'RSSI' Not currently implemented
txBufferA[7] = 0x00; //'Options' Not currently implemented
for(i = 0; i < pld_len; i++) {
checksum += pld_str[i];
txBufferA[RX_FRAME_OFFSET + i] = pld_str[i];
}
txBufferA[RX_FRAME_OFFSET + pld_len] = 0xFF - checksum; //set Checksum byte
//CRITICAL_SECTION_END
// pld_len + RX_FRAME_OFFSET + length(CHKSUM) - 1
DMA6CNT = pld_len + RX_FRAME_OFFSET;
DMA6CONbits.CHEN = 1;
DMA6REQbits.FORCE = 1;
}