Serial comms implementation

Collaboration diagram for Serial comms implementation:

Modules
	Serial return codes sent to TS
	Hard coded response for some TS messages

Typedefs
using	crc_t = uint32_t

Functions
void	processSerialCommand (void)
	Processes a message once it has been fully received.
void	sendToothLog (void)
	Should be called when serialStatusFlag == SERIAL_TRANSMIT_TOOTH_INPROGRESS,.
void	sendCompositeLog (void)
	Should be called when serialStatusFlag == LOG_SEND_COMPOSITE.
bool	isRxTimeout (void)
	Has the current receive operation timed out?
void	flushRXbuffer (void)
	Flush all remaining bytes from the rx serial buffer.
static uint32_t	reverse_bytes (uint32_t i)
	Reverse the byte order of a uint32_t.
void	writeByteReliableBlocking (byte value)
static void	readSerialTimeout (char *buffer, size_t length)
	Read from the serial port into the supplied buffer.
template<typename TIntegral >
static TIntegral	readSerialIntegralTimeout (void)
	Reads an integral type, timing out if necessary.
static uint32_t	serialWrite (uint32_t value)
	Write a uint32_t to Serial.
static void	serialWrite (uint16_t value)
	Write a uint16_t to Serial.
static uint16_t	writeNonBlocking (const byte *buffer, size_t length)
	Send as much data as possible without blocking the caller.
static size_t	writeNonBlocking (size_t start, uint32_t value)
	Write a uint32_t to Serial without blocking the caller.
static uint16_t	sendBufferAndCrcNonBlocking (const byte *buffer, size_t start, size_t length)
	Send the buffer, followed by it's CRC.
static void	sendSerialPayloadNonBlocking (uint16_t payloadLength)
	Start sending the shared serialPayload buffer.
static void	sendReturnCodeMsg (byte returnCode)
	Send a message to TS containing only a return code.
static bool	updatePageValues (uint8_t pageNum, uint16_t offset, const byte *buffer, uint16_t length)
	Update a pages contents from a buffer.
static void	loadPageValuesToBuffer (uint8_t pageNum, uint16_t offset, byte *buffer, uint16_t length)
	Loads a pages contents into a buffer.
static void	generateLiveValues (uint16_t offset, uint16_t packetLength)
	Send a status record back to tuning/logging SW. This will "live" information from currentStatus struct.
static void	loadO2CalibrationChunk (uint16_t offset, uint16_t chunkSize)
	Update the oxygen sensor table from serialPayload.
static uint16_t	toTemperature (byte lo, byte hi)
	Convert 2 bytes into an offset temperature in degrees Celsius.
static void	processTemperatureCalibrationTableUpdate (uint16_t calibrationLength, uint8_t calibrationPage, uint16_t *values, uint16_t *bins)
	Update a temperature calibration table from serialPayload.
void	serialReceive (void)
	The serial receive pump. Should be called whenever the serial port has data available to read.
void	serialTransmit (void)
	The serial transmit pump. Should be called when serialStatusFlag indicates a transmit operation is in progress.

Variables
static constexpr uint8_t	SEND_OUTPUT_CHANNELS = 48U
	Code for the "send output channels command".
static uint16_t	serialBytesRxTx = 0
	The number of bytes received or transmitted to date during nonblocking I/O.
static constexpr uint16_t	SERIAL_TIMEOUT = 400
	Timeout threshold in milliseconds.
uint32_t	serialReceiveStartTime = 0
	The time in milliseconds at which the serial receive started. Used for calculating whether a timeout has occurred.
static FastCRC32	CRC32_serial
	Support accumulation of a CRC during non-blocking operations.
static FastCRC32	CRC32_calibration
	Support accumulation of a CRC during calibration loads. Must be a separate instance to CRC32_serial due to calibration data being sent in multiple packets.
static uint8_t	serialPayload [SERIAL_BUFFER_SIZE]
	Serial payload buffer.
static uint16_t	serialPayloadLength = 0
	How many bytes in serialPayload were received or sent.
Stream *	pPrimarySerial

Detailed Description

Typedef Documentation

crc_t

using crc_t = uint32_t

Function Documentation

flushRXbuffer()

void flushRXbuffer

(

void

)

Flush all remaining bytes from the rx serial buffer.

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generateLiveValues()

static void generateLiveValues ( uint16_t  offset, uint16_t  packetLength  )

static

Send a status record back to tuning/logging SW. This will "live" information from currentStatus struct.

Parameters

offset	- Start field number
packetLength	- Length of actual message (after possible ack/confirm headers) E.g. tuning sw command 'A' (Send all values) will send data from field number 0, LOG_ENTRY_SIZE fields.

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isRxTimeout()

bool isRxTimeout

(

void

)

Has the current receive operation timed out?

Checks whether the current serial command should be timed out.

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loadO2CalibrationChunk()

static void loadO2CalibrationChunk ( uint16_t  offset, uint16_t  chunkSize  )

static

Update the oxygen sensor table from serialPayload.

Parameters

offset	Offset into serialPayload and the table
chunkSize	Number of bytes available in serialPayload

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loadPageValuesToBuffer()

static void loadPageValuesToBuffer ( uint8_t  pageNum, uint16_t  offset, byte *  buffer, uint16_t  length  )

static

Loads a pages contents into a buffer.

Parameters

pageNum	The index of the page to update
offset	Offset into the page
buffer	The buffer to read from
length	The buffer length

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processSerialCommand()

void processSerialCommand

(

void

)

Processes a message once it has been fully received.

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processTemperatureCalibrationTableUpdate()

static void processTemperatureCalibrationTableUpdate ( uint16_t  calibrationLength, uint8_t  calibrationPage, uint16_t *  values, uint16_t *  bins  )

static

Update a temperature calibration table from serialPayload.

Parameters

calibrationLength	The chunk size received from TS
calibrationPage	Index of the table
values	The table values
bins	The table bin values

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readSerialIntegralTimeout()

template<typename TIntegral >

static TIntegral readSerialIntegralTimeout ( void  )

static

Reads an integral type, timing out if necessary.

Template Parameters

TIntegral

The integral type. E.g. uint16_t

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readSerialTimeout()

static void readSerialTimeout ( char *  buffer, size_t  length  )

static

Read from the serial port into the supplied buffer.

Attention

The buffer is filled in reverse, since TS comms is little-endian.

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reverse_bytes()

static uint32_t reverse_bytes ( uint32_t  i )

static

Reverse the byte order of a uint32_t.

Attention

noinline is needed to prevent enlarging callers stack frame, which in turn throws off free ram reporting.

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sendBufferAndCrcNonBlocking()

static uint16_t sendBufferAndCrcNonBlocking ( const byte *  buffer, size_t  start, size_t  length  )

static

Send the buffer, followed by it's CRC.

This is supposed to be called multiple times for the same buffer until it's all sent.

Parameters

buffer	The buffer
start	Index into the buffer to start sending at. [0, length)
length	Total size of the buffer

Returns

Cumulative total number of bytes written . I.e. the next start value

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sendCompositeLog()

void sendCompositeLog

(

void

)

Should be called when serialStatusFlag == LOG_SEND_COMPOSITE.

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sendReturnCodeMsg()

static void sendReturnCodeMsg ( byte  returnCode )

static

Send a message to TS containing only a return code.

This is used when TS asks for an action to happen (E.g. start a logger) or to signal an error condition to TS

Attention

This is a blocking operation

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sendSerialPayloadNonBlocking()

static void sendSerialPayloadNonBlocking ( uint16_t  payloadLength )

static

Start sending the shared serialPayload buffer.

serialStatusFlag will be signal the result of the send:
serialStatusFlag == SERIAL_INACTIVE: send is complete
serialStatusFlag == SERIAL_TRANSMIT_INPROGRESS: partial send, subsequent calls to continueSerialTransmission will finish sending serialPayload

Parameters

payloadLength

How many bytes to send [0, sizeof(serialPayload))

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sendToothLog()

void sendToothLog

(

void

)

Should be called when serialStatusFlag == SERIAL_TRANSMIT_TOOTH_INPROGRESS,.

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serialReceive()

void serialReceive

(

void

)

The serial receive pump. Should be called whenever the serial port has data available to read.

Processes the incoming data on the serial buffer based on the command sent. Can be either data for a new command or a continuation of data for command that is already in progress:

Commands are single byte (letter symbol) commands.

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serialTransmit()

void serialTransmit

(

void

)

The serial transmit pump. Should be called when serialStatusFlag indicates a transmit operation is in progress.

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serialWrite() [1/2]

static void serialWrite ( uint16_t  value )

static

Write a uint16_t to Serial.

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serialWrite() [2/2]

static uint32_t serialWrite ( uint32_t  value )

static

Write a uint32_t to Serial.

Returns

The value as transmitted on the wire

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toTemperature()

static uint16_t toTemperature ( byte  lo, byte  hi  )

static

Convert 2 bytes into an offset temperature in degrees Celsius.

Attention

Returned value will be offset CALIBRATION_TEMPERATURE_OFFSET

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updatePageValues()

static bool updatePageValues ( uint8_t  pageNum, uint16_t  offset, const byte *  buffer, uint16_t  length  )

static

Update a pages contents from a buffer.

Parameters

pageNum	The index of the page to update
offset	Offset into the page
buffer	The buffer to read from
length	The buffer length

Returns

true if page updated successfully

false if page cannot be updated

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writeByteReliableBlocking()

void writeByteReliableBlocking

(

byte

value

)

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writeNonBlocking() [1/2]

static uint16_t writeNonBlocking ( const byte *  buffer, size_t  length  )

static

Send as much data as possible without blocking the caller.

Returns

Number of bytes sent

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writeNonBlocking() [2/2]

static size_t writeNonBlocking ( size_t  start, uint32_t  value  )

static

Write a uint32_t to Serial without blocking the caller.

Returns

Number of bytes sent

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Variable Documentation

CRC32_calibration

FastCRC32 CRC32_calibration

static

Support accumulation of a CRC during calibration loads. Must be a separate instance to CRC32_serial due to calibration data being sent in multiple packets.

CRC32_serial

FastCRC32 CRC32_serial

static

Support accumulation of a CRC during non-blocking operations.

pPrimarySerial

Stream* pPrimarySerial

SEND_OUTPUT_CHANNELS

constexpr uint8_t SEND_OUTPUT_CHANNELS = 48U

staticconstexpr

Code for the "send output channels command".

SERIAL_TIMEOUT

constexpr uint16_t SERIAL_TIMEOUT = 400

staticconstexpr

Timeout threshold in milliseconds.

serialBytesRxTx

uint16_t serialBytesRxTx = 0

static

The number of bytes received or transmitted to date during nonblocking I/O.

Note

We can share one variable between rx & tx because we only support simplex serial comms. I.e. we can only be receiving or transmitting at any one time.

serialPayload

uint8_t serialPayload[SERIAL_BUFFER_SIZE]

static

Serial payload buffer.

serialPayloadLength

uint16_t serialPayloadLength = 0

static

How many bytes in serialPayload were received or sent.

serialReceiveStartTime

uint32_t serialReceiveStartTime = 0

The time in milliseconds at which the serial receive started. Used for calculating whether a timeout has occurred.