1. Chip Config & Drivers – Required Drivers:
Software UART to send/receive packets to/from UHF/VHF radio.
USART0
SPI Driver for SD Card – Driver that the FAT32 file system will use the read and write data to the SD Flash Card. (need to turn off when so it doesn’t listen to I2C)
Flight Computer Comm. – Driver that will do communication between Flight Computer and Electrical Power System. (I2C)
I2C Comm. between RTC and WDT on System Support Module – Driver that will send and Receive I2C packets to RTC and WDT. (need to enable)
I2C Comm. between Flight Computer and UHF/VHF Radio – Driver will send/receive packets to/from UHF/VHF Radio via I2C.
USART1
S-Band Radio Comm. – Driver that will send/receive packets to/from the S-Band Radio. (UART)
Heat On – Driver will turn the Heater on for various reasons. Will use a GPIO (Does this driver need to worry about battery voltage?)
Function (Input from System Support Module) – Use 3 GPIO. (Future communication scheme)
Off Vcc (Input from System Support Module) – Use a GPIO.
Antenna Deployment Signal – Driver that will deploy antenna, use 2 GPIO.
Camera On – Driver that will power on the camera, use a GPIO.
Analog Audio to UHF/VHF Radio – Driver will output analog signal to radio. (Up call in ISR at 8kHz)

2. Current Status Working Driver(s) Driver(s) in the pipeline SW UART I2C
Buffered receive and transmit
FIFO buffers
Driver(s) in the pipeline
I2C
Uart0
Uart1

3. SwUartTxDriver - Design
Tx Ring Buffer
Tx FSM Diagram
Key
old
new
State
output
If no char in buffer
Idle A
Stop
high
Start
Low
St0
bit0
St7
bit7
If char found in buffer
St6
bit6
St1
bit1
ASCII characters are removed from Tx ring buffer bit by bit.
St5
bit5
St2
bit2
St4
bit4
St3
bit3

4. SwUartTxDriver - Functions
ubyte SwUartTxCheckBuff(void)
Function used to get the status of the Tx FIFO ring buffer used
void SwUartTxPutC(ubyte inchar)
Function Used to insert characters into the Tx FIFO ring buffer
If buffer is full function will spin until the ISR has taken a character out of the Tx FIFO ring buffer
void SwUartTxPutS(ubyte *instr)
Function used to put a character string into the Tx FIFO ring buffer
Function makes multiple calls of SwUartTxPutC
void IsrSwUartTxBitShift(void)
Function to implement the Tx FSM within the Timer_A ISR to shift out the bit of each character
Function will be called every 4800 baud half bit time within ISR

5. SwUartRxDriver - Design
Rx Ring Buffer
Key
Rx FSM Diagram
old
State
output
new
While no input
Idle A
Stop
high
Start
Low
St0
bit0
St7
bit7
When ISR is made
St6
bit6
St1
bit1
ASCII characters are inserted into the Rx ring buffer bit by bit.
St5
bit5
St2
bit2
St4
bit4
St3
bit3

6. SwUartRxDriver - Functions
ubyte SwUartRxGetC(void)
Function used to get a character out of the Rx FIFO ring buffer
Function will return character if one is present and return NULL_UBYTE if the buffer is empty
ubyte SwUartRxCheckBuff(void)
Function used to get the status of the Rx FIFO ring buffer used
ubyte SwUartRxPutC(ubyte inchar)
Function used by ISR to put characters in the Rx FIFO buffer
Function will return one of the following values: SWUART_RXBUFF_ERRORFULL, SWUART_RXBUFF_NOERROR
void SwUartRxStart(void)
Function used by Port2 ISR to start Rx FSM
void IsrSwUartRxBitTake(void)
Function implements FSM to shift in bits to receive a single character and put character into buffer
Function will be called every half bit time at 4800 baud within ISR

7. TESTING
Development board was hooked up to a Terminal Software, SW UART was made to echo what was sent to it. Also, multiple characters were sent and the SW UART echoed back the entire packet after \r.
Packet Rx/Tx has been tested using SW UART without any problem with the driver.

8. Hardware Map Timer A : TMRA3
19200 Hz interrupts (4800 baud generation at 4x for signal pseudo-sync)
Software UART Receive
1200 Hz interrupts (1200 baud generation for signal pseudo-sync)
Software UART Transmit
Timer B : TMRB7
8000 Hz interrupts
Analog Audio
100 Hz interrupts
OS Tick
Sensor Acquisition*
Analog to Digital Converter : ADC12
Analog audio in
8 bit samples
Digital to Analog Converter : DAC12
Analog audio out
Receiver/Transmitter One : USART1
UART
MHX [ | | 9600 | 1200 ]
Port Interrupts
Software UART Receive Sync
DTMF Valid Signal*
Supervisor Serial Interface (Currently Undefined)*
Receiver/Transmitter Zero : USART0
UART
Camera at [ | | 9600 ] baud (others available)
SPI
SD Flash Mass Storage (Unknown max flash speed. Test at uC max and backoff as necessary.)
I2C
Speed
400khz by spec. Drive at [ 200k | 100k | 50k ].
Devices
Camera Temperature
Radio TX/RX/AMP Binary Power Control
Radio TX Current
Radio RX Current
Power System

9. FUTURE I2C, Uart0 and Uart1 drivers are in progress (80%) done.
Buffers have been written for USART1 and USART0 in UART mode.
SPI drivers under research and conversation. Looking at file system calls to drivers so they can be integrated.