Machine_State TDMA_Assign(uint32_t *cycles, uint8_t ch_addr) {
volatile struct Listen_Struct RX_Message;
RX_Message = LBT_Listen(0); // listen forever until the packet is received
*cycles = long_int_merge(RX_Message.payload[CYCLES_POS_LOWER],
RX_Message.payload[CYCLES_POS_MIDDLE],
RX_Message.payload[CYCLES_POS_UPPER]);
Radio_Sleep();
Sleep_Timer(*cycles - GT);
return Sensing;
}
struct Listen_Struct LBT_Listen(uint16_t timeoutPeriod)
{
uint8_t Old_GDO;
uint8_t Old_MSP_RX_Port_IES;
uint8_t Old_MSP_RX_Port_IE;
uint8_t Old_MSP_RX_Port_Out;
uint8_t status;
uint8_t state;
uint8_t buffer[64];
LBT_Status return_status;
struct Listen_Struct retVal;
// Flush the RX FIFO
SPI_Strobe(SFRX, Get_RX_FIFO);
// Configure machine state
SPI_Read(GDO_RX, &Old_GDO); // Capture and save the old setting for the GDO pin
Old_MSP_RX_Port_IES = MSP_RX_Port_IES; // Save the old interrupt edge select value
Old_MSP_RX_Port_IE = MSP_RX_Port_IE; // Save the old interrupt enable value
Old_MSP_RX_Port_Out = MSP_RX_Port_OUT;
status = SPI_Send(GDO_RX, 0x07); // Set the GDO to assert on pkt recieve with crc OK
state = status & State_Bits; // Mask off the state bits from the status byte
if(state != SB_Idle) // If a radio is already busy
{
return_status = Radio_Busy;
goto Cleanup; // Yes. A Goddamn goto.
}
// Set GDO pin to trigger on rising edge for PKT RX
MSP_RX_Port_IES &= ~MSP_RX_Port_IE;
MSP_RX_Port_IE |= MSP_RX_Port_IE;
SPI_Strobe(SRX, Get_RX_FIFO); // Set radio to listen
Sleep_Timer(0, timeoutPeriod);
SPI_Read_Status(RXBYTES, &status); // Get packet status
if(status & OverFlow) // If the buffer is overflowed dump it and don't read the values
{
return_status = RX_Buffer_Overflow;
SPI_Strobe(SFRX, Get_RX_FIFO);
goto Cleanup;
}
// Read the FIFO buffer into the out variable. IF there is no overflow then contents of the RXBYTES register is just the
// number of bytes in the RX FIFO.
SPI_Read_Burst(RXFIFO, buffer, status);
return_status = Message_Recieved;
retVal.length = buffer[0] - 5;
retVal.address = buffer[1];
retVal.signal = buffer[status - 2];
retVal.Status = return_status;
uint8_t i;
for(i = 0; i < status - 5; i++)
{
retVal.payload[i] = buffer[i + 3];
}
Cleanup:
// Restore old machine state
MSP_RX_Port_IE = Old_MSP_RX_Port_IE; // Restore the old interrupt enable value
MSP_RX_Port_IFG &= ~MSP_RX_Pin; // Clear interrupt flags before exit
MSP_RX_Port_IES = Old_MSP_RX_Port_IES; // Restore the old interrupt edge select value
MSP_RX_Port_OUT = Old_MSP_RX_Port_Out; // Restore the old port setting
SPI_Send(GDO_RX, Old_GDO); // Set the GDO pin back to its old function
return retVal;
}
LBT_Status LBT_Send(uint8_t dest_address, uint8_t source_address, uint8_t *message, uint8_t length)
{
uint8_t status;
uint8_t state;
uint8_t FIFO_Space;
uint8_t Old_GDO;
uint8_t Old_MSP_RX_Port_IES;
uint8_t Old_MSP_RX_Port_IE;
uint8_t Old_MSP_RX_Port_Out;
LBT_Status return_status;
// Configure machine state
SPI_Read(GDO_RX, &Old_GDO); // Capture and save the old setting for the GDO pin
Old_MSP_RX_Port_IES = MSP_RX_Port_IES; // Save the old interrupt edge select value
Old_MSP_RX_Port_IE = MSP_RX_Port_IE; // Save the old interrupt enable value
Old_MSP_RX_Port_Out = MSP_RX_Port_OUT; // Save the old value of the GDO pin port
MSP_RX_Port_OUT &= ~MSP_RX_Pin;
status = SPI_Send(GDO_RX, 0x06); // Set the GDO to assert on preamble start and TX complete
state = status & State_Bits; // Mask off the state bits from the status byte
if(state != SB_Idle) // If a TX was already in progress.
{
return_status = Radio_Busy;
goto Cleanup; // Yes. A Goddamn goto.
}
// Change to recieve mode to check for clear channel
SPI_Strobe(SRX, Get_TX_FIFO); // Listen before transmit
Sleep_Timer(0,328); // Sleep 10 ms
SPI_Read_Status(PKTSTATUS, &status); // Get packet status
if(!(status & BIT4)) // Check for clear channel. If true then a carrier signal was recv'd and a collision occured.
{
return_status = Channel_Busy; // shit!
goto Cleanup;
}
SPI_Strobe(SIDLE, Get_TX_FIFO); // stop the radio
// Load the TX fifo
SPI_Send(TXFIFO, length + 2);
SPI_Send(TXFIFO, dest_address);
SPI_Send(TXFIFO, source_address);
status = SPI_Send_Burst(TXFIFO, message, length); // Load the TX fifo
FIFO_Space = status & FIFO_Bytes; // Get the space left in the FIFO
if(FIFO_Space == 0) // FIFO space remaining of 0 means overflow
{
return_status = TX_Buffer_Overflow;
goto Cleanup;
}
// Enable interrupt on falling edge
MSP_RX_Port_IES |= MSP_RX_Pin;
MSP_RX_Port_IE |= MSP_RX_Pin;
SPI_Strobe(STX, Get_TX_FIFO); // Tell radio to transmit
LPM3; // Sleep until TX is done, interrupt will wake up the
return_status = Transmit_Success;
// Clear the interrupt and set the GDO pin back to its old function here. n
Cleanup:
MSP_RX_Port_IFG &= ~MSP_RX_Pin; // Clear interrupt flags before exit
MSP_RX_Port_IES = Old_MSP_RX_Port_IES; // Restore the old interrupt edge select value
MSP_RX_Port_IE = Old_MSP_RX_Port_IE; // Restore the old interrupt enable value
MSP_RX_Port_OUT = Old_MSP_RX_Port_Out; // Restore the old port setting
SPI_Send(GDO_RX, Old_GDO); // Set the GDO pin back to its old function
return return_status;
}
