Pseudocode for DOGTXmitSM.c

InitDOGTXmitSM
	Initialize into the first state, WaitingToSendFirstByte
	Set CurrentState to WaitingToSendFirstByte
	Post the initial transition event
end InitDOGTXmitSM


RunDOGTXmitSM
	switch on CurrentState
		case WaitingToSendFirstByte state
			if the event type is ES_BEGIN_TXMIT	
				Save the event param that describes the packet type
        		If constructing the packet of specified type is successful
				Reset the index of number of bytes sent
				Set CurrentState to SendingAPacket
				Begin transmitting by calling helper function
			else 		
				constructing packet failed, do nothing
			end if
			break
    	case SendingAPacket state
			if the event type is ES_ALL_BYTES_SENT
				Set CurrentState to WaitingToSendFirstByte
			else if the event type is ES_LOST_CONNECTION
				Set CurrentState to WaitingToSendFirstByte
			end if
      		break
	end switch on Current State
  	return ReturnEvent
end RunDOGTXmitSM


DOGTXmitISR

	(Only respond to the interrupt that we care about: TXMIS)
	If transmit interrupts are unmasked and it fired
		Clear UART TXmit interrupt by setting TXIC in UARTICR (interrupt clear register)
		
		if we have sent all of the bytes
			Disable UART TXmit interrupt by clearing interrupt mask bit in UART mask reg
			Post ES_ALL_BYTES_SENT to TXmitSM
		else (we are not done sending bytes yet)
			Write the new data to data register UARTDR
			Increment BytesSentIndex
		end if
	else
		(TXMIS is not set, meaning it's not a transmit interrupt, so take no action)
	end if 
end DOGTXmitISR


ConstructPacket
	Constructs the packet that will be sent by filling out the
	TxPacket array with appropriate data
 
 	If PacketType is STATUS
 		Set PacketSize accordingly
		Set FrameDataSize accordingly
		Get destination address from RX service
		Create XBee header
		Fill out RF data of TxPacket (just using PacketType)
		Then fill out RF data of TxPacket using getter function for IMU data
		Create an index variable to track RF data byte that's being set to a status byte
		start the 'for' loop at RF data start +1 because of the PacketType bit that's first
			looping over the IMU data using the getter function, save each to TxPacket
		SetXBeeChecksum
		Return true because packet was created successfully
 	else if PacketType is ENCR_RESET
		Set PacketSize accordingly
		Set FrameDataSize accordingly
		Get destination address from RX service
		Create XBee header
		Fill out RF data of TxPacket (just using PacketType)
		SetXBeeChecksum
		Return true because packet was created successfully
	else if PacketType is PAIR_ACK
		Set PacketSize accordingly
		Set FrameDataSize accordingly
		Get destination address from RX service
		Create XBee header
		Fill out RF data of TxPacket (just using PacketType)
		SetXBeeChecksum
		Return true because packet was created successfully
	else 
		bad packet type, packet was not created. return false
	end if
end ConstructPacket


CreateXBeeHeader
	Creates the header, which is all the bytes before the RF data
	
	TxPacket[0] equals 0x7E 
	TxPacket[1] equals length of MSB which is 0x00
	TxPacket[2] equals length of LSB
	TxPacket[3] equals API_ID for a transmit request
	TxPacket[4] equals FRAME_ID which is arbitrary, not specified in comm protocol
	TxPacket[5] equals Destination Address MSB
	TxPacket[6] equals Destination Address LSB
	TxPacket[7] equals OPTIONS, which in our case is 0x00
end CreateXBeeHeader



SetXBeeChecksum

	Calculates checksum and puts that value in last byte of TxPacket[]
	
	for each byte in the framing data
		Add current TxPacket to the sum
	end for loop
	Calculate XBeeChecksum by subtracting sum from 0xff

	Set the last byte in the TxPacket array to be the XBeeCheckSum that was just calculated
end SetXBeeChecksum
		


StartDOGTXmit
Kicks off transmission of a packet and will cause a UART Tx interrupt, 
	which will be handled in DOGTXmitISR

	if there is room to transfer a byte (Txmit Fifo Empty = TXFE is set)
		Write the new data to data register UARTDR
		Enable UART TXmit interrupt by setting interrupt mask bit in UART mask reg
		so that when the byte is done sending, it fires an interrupt
		Increment BytesSentIndex (goes from 0 to 1 here)
		Return true because first byte was successfully transmitted
	else (there is not room to transmit a byte because the transmit fifo is full)
		return false
	end if
end StartDOGTXmit