Description

Use the Asynchronous Serial Host (ASH) Framework interfaces on a host microcontroller when it communicates with an Ember chip via EZSP-UART.

See ash-common.h for source code.

See ash-protocol.h for source code.

Functions
uint8_t	ashEncodeByte (uint8_t len, uint8_t byte, uint8_t *offset)
	Builds an ASH frame.

EzspStatus	ashDecodeByte (uint8_t byte, uint8_t out, uint8_t outLen)
	Decodes and validates an ASH frame.

uint8_t	ashRandomizeArray (uint8_t seed, uint8_t *buf, uint8_t len)
	Randomizes array contents by XORing with an 8-bit pseudo random sequence.

void	ashStartAckTimer (void)
	Sets ashAckTimer to the specified period and starts it running.

bool	ashAckTimerHasExpired (void)
	Indicates whether or not ashAckTimer has expired.

void	ashAdjustAckPeriod (bool expired)
	Adapts the acknowledgement timer period to the observed ACK delay.

void	ashStartNrTimer (void)
	Starts the Not Ready timer.

bool	ashNrTimerHasExpired (void)
	Tests whether the Not Ready timer has expired or has stopped.

Macros
#define	ashStopAckTimer (void) do { ashAckTimer = 0; } while (false)
	Stops and clears ashAckTimer.

#define	ashAckTimerIsRunning () (ashAckTimer != 0)
	Indicates whether or not ashAckTimer is currently running.

#define	ashAckTimerIsNotRunning () (ashAckTimer == 0)
	Indicates whether or not ashAckTimer is currently running.

#define	ashSetAckPeriod (msec) do { ashAckPeriod = msec; ashAckTimer = 0; } while (false)
	Sets the acknowledgement timer period (in msec) and stops the timer.

#define	ashGetAckPeriod () (ashAckPeriod)
	Returns the acknowledgement timer period (in msec).

#define	ashSetAndStartAckTimer (msec) do { ashSetAckPeriod (msec); ashStartAckTimer (); } while (false)
	Sets the acknowledgement timer period (in msec), and starts the timer running.

#define	ASH_NR_TIMER_BIT 4

#define	ashStopNrTimer () do { ashNrTimer = 0; } while (false)
	Stops the Not Ready timer.

#define	ashNrTimerIsNotRunning () (ashAckTimer == 0)
	Indicates whether or not ashNrTimer is currently running.

#define	ASH_VERSION 2

#define	ASH_FLAG 0x7E
	frame delimiter

#define	ASH_ESC 0x7D
	byte stuffing escape byte

#define	ASH_XON 0x11
	flow control byte - means resume transmission

#define	ASH_XOFF 0x13
	flow control byte - means suspend transmission

#define	ASH_SUB 0x18
	replaces bytes w framing, overrun or overflow errors

#define	ASH_CAN 0x1A
	frame cancel byte

#define	ASH_WAKE 0xFF
	wake signal byte (also means NCP data pending)

#define	ASH_FLIP 0x20
	XOR mask used in byte stuffing.

#define	ASH_MIN_DATA_FIELD_LEN EZSP_MIN_FRAME_LENGTH

#define	ASH_MAX_DATA_FIELD_LEN EZSP_MAX_FRAME_LENGTH

#define	ASH_MIN_DATA_FRAME_LEN (ASH_MIN_DATA_FIELD_LEN + 1)

#define	ASH_MIN_FRAME_LEN 1

#define	ASH_MAX_FRAME_LEN (ASH_MAX_DATA_FIELD_LEN + 1)

#define	ASH_CRC_LEN 2

#define	ASH_MIN_FRAME_WITH_CRC_LEN (ASH_MIN_FRAME_LEN + ASH_CRC_LEN)

#define	ASH_MAX_FRAME_WITH_CRC_LEN (ASH_MAX_FRAME_LEN + ASH_CRC_LEN)

#define	ASH_NCP_SHFRAME_RX_LEN 2
	longest non-data frame received

#define	ASH_NCP_SHFRAME_TX_LEN 3
	longest non-data frame sent

#define	ASH_HOST_SHFRAME_RX_LEN 3
	longest non-data frame received

#define	ASH_HOST_SHFRAME_TX_LEN 2
	longest non-data frame sent

#define	ASH_DFRAME_MASK 0x80

#define	ASH_CONTROL_DATA 0x00

#define	ASH_SHFRAME_MASK 0xE0

#define	ASH_CONTROL_ACK 0x80

#define	ASH_CONTROL_NAK 0xA0

#define	ASH_CONTROL_RST 0xC0

#define	ASH_CONTROL_RSTACK 0xC1

#define	ASH_CONTROL_ERROR 0xC2

#define	ASH_ACKNUM_MASK 0x07
	acknowledge frame number

#define	ASH_ACKNUM_BIT 0

#define	ASH_RFLAG_MASK 0x08
	retransmitted frame flag

#define	ASH_RFLAG_BIT 3

#define	ASH_NFLAG_MASK 0x08
	receiver not ready flag

#define	ASH_NFLAG_BIT 3

#define	ASH_PFLAG_MASK 0x10
	flag reserved for future use

#define	ASH_PFLAG_BIT 4

#define	ASH_FRMNUM_MASK 0x70
	DATA frame number.

#define	ASH_FRMNUM_BIT 4

#define	ASH_GET_RFLAG (ctl) ((ctl & ASH_RFLAG_MASK ) >> ASH_RFLAG_BIT)

#define	ASH_GET_NFLAG (ctl) ((ctl & ASH_NFLAG_MASK ) >> ASH_NFLAG_BIT)

#define	ASH_GET_FRMNUM (ctl) ((ctl & ASH_FRMNUM_MASK ) >> ASH_FRMNUM_BIT)

#define	ASH_GET_ACKNUM (ctl) ((ctl & ASH_ACKNUM_MASK ) >> ASH_ACKNUM_BIT)

#define	ASH_FRAME_LEN_DATA_MIN (ASH_MIN_DATA_FIELD_LEN + 1)

#define	ASH_FRAME_LEN_ACK 1

#define	ASH_FRAME_LEN_NAK 1

#define	ASH_FRAME_LEN_RST 1

#define	ASH_FRAME_LEN_RSTACK 3

#define	ASH_FRAME_LEN_ERROR 3

#define	MOD8 (n) ((n) & 7)
	mask to frame number modulus

#define	INC8 (n) (n = ( MOD8 (n + 1)))
	increment in frame number modulus

#define	WITHIN_RANGE (lo, n, hi) ( MOD8 (n - lo) <= MOD8 (hi - lo))

Variables
bool	ashDecodeInProgress

uint16_t	ashAckTimer

uint16_t	ashAckPeriod

uint8_t	ashNrTimer

Function Documentation

◆ ashEncodeByte()

uint8_t ashEncodeByte	(	uint8_t	`len,`
		uint8_t	`byte,`
		uint8_t *	`offset`
	)

Builds an ASH frame.

Byte stuffs the control and data fields as required, computes and appends the CRC and adds the ending flag byte. Called with the next byte to encode, this function may return several output bytes before it's ready for the next byte.

Parameters

`len`	new frame flag / length of the frame to be encoded. A non-zero value begins a new frame, so all subsequent calls must use zero. The length includes control byte and data field, but not the flag or crc. This function does not validate the length.
`byte`	the next byte of data to add to the frame. Note that in general the same byte of data may have to be passed more than once as escape bytes, the CRC and the end flag byte are output.
`offset`	pointer to the offset of the next input byte. (If the frame data is the array data[], the next byte would be data[offset].) Is set to 0 when starting a new frame (ie, len is non-zero). Is set to 0xFF when the last byte of the frame is returned.

Returns: next encoded output byte in frame.

◆ ashDecodeByte()

EzspStatus ashDecodeByte	(	uint8_t	`byte,`
		uint8_t *	`out,`
		uint8_t *	`outLen`
	)

Decodes and validates an ASH frame.

Data is passed to it one byte at a time. Decodes byte stuffing, checks crc, finds the end flag and (if enabled) terminates the frame early on CAN or SUB bytes. The number of bytes output will not exceed the max valid frame length, which does not include the flag or the crc.

Parameters

`byte`	the next byte of data to add to the frame
`out`	pointer to where to write an output byte
`outLen`	number of bytes output so far

Returns

status of frame decoding

::EZSP_SUCCESS
::EZSP_ASH_IN_PROGRESS
::EZSP_ASH_CANCELLED
::EZSP_ASH_BAD_CRC
::EZSP_ASH_COMM_ERROR
::EZSP_ASH_TOO_SHORT
::EZSP_ASH_TOO_LONG

◆ ashRandomizeArray()

uint8_t ashRandomizeArray	(	uint8_t	`seed,`
		uint8_t *	`buf,`
		uint8_t	`len`
	)

Randomizes array contents by XORing with an 8-bit pseudo random sequence.

This reduces the likelihood that byte-stuffing will greatly increase the size of the payload. (This could happen if a DATA frame contained repeated instances of the same reserved byte value.)

Parameters

`seed`	zero initializes the random sequence a non-zero value continues from a previous invocation
`buf`	pointer to the array whose contents will be randomized
`len`	number of bytes in the array to modify

Returns: last value of the sequence. If a buffer is processed in two or more chunks, as with linked buffers, this value should be passed back as the value of the seed argument

◆ ashStartAckTimer()

void ashStartAckTimer ( void )

Sets ashAckTimer to the specified period and starts it running.

◆ ashAckTimerHasExpired()

bool ashAckTimerHasExpired ( void )

Indicates whether or not ashAckTimer has expired.

If the timer is stopped then it is not expired.

◆ ashAdjustAckPeriod()

void ashAdjustAckPeriod ( bool expired )

Adapts the acknowledgement timer period to the observed ACK delay.

If the timer is not running, it does nothing. If the timer has expired, the timeourt period is doubled. If the timer has not expired, the elapsed time is fed into simple IIR filter: T[n+1] = (7*T[n] + elapsedTime) / 8 The timeout period, ashAckPeriod, is limited such that: ASH_xxx_TIME_DATA_MIN <= ashAckPeriod <= ASH_xxx_TIME_DATA_MAX, where xxx is either HOST or NCP.

The acknowledgement timer is always stopped by this function.

Parameters

expired true if timer has expired

◆ ashStartNrTimer()

void ashStartNrTimer ( void )

Starts the Not Ready timer.

On the host, this times nFlag refreshing when the host doesn't have room for callbacks for a prolonged period.

On the NCP, if this times out the NCP resumes sending callbacks.

◆ ashNrTimerHasExpired()

bool ashNrTimerHasExpired ( void )

Tests whether the Not Ready timer has expired or has stopped.

If expired, it is stopped.

Returns: true if the Not Ready timer has expired or stopped

Macro Definition Documentation

◆ ashStopAckTimer

void ashStopAckTimer ( ) do { ashAckTimer = 0; } while (false)

Stops and clears ashAckTimer.

◆ ashAckTimerIsRunning

#define ashAckTimerIsRunning ( ) (ashAckTimer != 0)

Indicates whether or not ashAckTimer is currently running.

The timer may be running even if expired.

◆ ashAckTimerIsNotRunning

#define ashAckTimerIsNotRunning ( ) (ashAckTimer == 0)

Indicates whether or not ashAckTimer is currently running.

The timer may be running even if expired.

◆ ashSetAckPeriod

#define ashSetAckPeriod ( msec ) do { ashAckPeriod = msec; ashAckTimer = 0; } while (false)

Sets the acknowledgement timer period (in msec) and stops the timer.

◆ ashGetAckPeriod

#define ashGetAckPeriod ( ) (ashAckPeriod)

Returns the acknowledgement timer period (in msec).

◆ ashSetAndStartAckTimer

#define ashSetAndStartAckTimer ( msec ) do { ashSetAckPeriod (msec); ashStartAckTimer (); } while (false)

Sets the acknowledgement timer period (in msec), and starts the timer running.

◆ ashStopNrTimer

#define ashStopNrTimer ( ) do { ashNrTimer = 0; } while (false)

Stops the Not Ready timer.

◆ ashNrTimerIsNotRunning

#define ashNrTimerIsNotRunning ( ) (ashAckTimer == 0)

Indicates whether or not ashNrTimer is currently running.

◆ ASH_FLAG

#define ASH_FLAG 0x7E

frame delimiter

◆ ASH_ESC

#define ASH_ESC 0x7D

byte stuffing escape byte

◆ ASH_XON

#define ASH_XON 0x11

flow control byte - means resume transmission

◆ ASH_XOFF

#define ASH_XOFF 0x13

flow control byte - means suspend transmission

◆ ASH_SUB

#define ASH_SUB 0x18

replaces bytes w framing, overrun or overflow errors

◆ ASH_CAN

#define ASH_CAN 0x1A

frame cancel byte

◆ ASH_WAKE

#define ASH_WAKE 0xFF

wake signal byte (also means NCP data pending)

◆ ASH_FLIP

#define ASH_FLIP 0x20

XOR mask used in byte stuffing.

◆ ASH_NCP_SHFRAME_RX_LEN

#define ASH_NCP_SHFRAME_RX_LEN 2

longest non-data frame received

◆ ASH_NCP_SHFRAME_TX_LEN

#define ASH_NCP_SHFRAME_TX_LEN 3

longest non-data frame sent

◆ ASH_HOST_SHFRAME_RX_LEN

#define ASH_HOST_SHFRAME_RX_LEN 3

longest non-data frame received

◆ ASH_HOST_SHFRAME_TX_LEN

#define ASH_HOST_SHFRAME_TX_LEN 2

longest non-data frame sent

◆ ASH_ACKNUM_MASK

#define ASH_ACKNUM_MASK 0x07

acknowledge frame number

◆ ASH_RFLAG_MASK

#define ASH_RFLAG_MASK 0x08

retransmitted frame flag

◆ ASH_NFLAG_MASK

#define ASH_NFLAG_MASK 0x08

receiver not ready flag

◆ ASH_PFLAG_MASK

#define ASH_PFLAG_MASK 0x10

flag reserved for future use

◆ ASH_FRMNUM_MASK

#define ASH_FRMNUM_MASK 0x70

DATA frame number.

◆ MOD8

#define MOD8 ( n ) ((n) & 7)

mask to frame number modulus

◆ INC8

#define INC8 ( n ) (n = ( MOD8 (n + 1)))

increment in frame number modulus

Ash

Description

Functions

Macros

Variables

Function Documentation

◆ ashEncodeByte()

◆ ashDecodeByte()

◆ ashRandomizeArray()

◆ ashStartAckTimer()

◆ ashAckTimerHasExpired()

◆ ashAdjustAckPeriod()

◆ ashStartNrTimer()

◆ ashNrTimerHasExpired()

Macro Definition Documentation

◆ ashStopAckTimer

◆ ashAckTimerIsRunning

◆ ashAckTimerIsNotRunning

◆ ashSetAckPeriod

◆ ashGetAckPeriod

◆ ashSetAndStartAckTimer

◆ ashStopNrTimer

◆ ashNrTimerIsNotRunning

◆ ASH_FLAG

◆ ASH_ESC

◆ ASH_XON

◆ ASH_XOFF

◆ ASH_SUB

◆ ASH_CAN

◆ ASH_WAKE

◆ ASH_FLIP

◆ ASH_NCP_SHFRAME_RX_LEN

◆ ASH_NCP_SHFRAME_TX_LEN

◆ ASH_HOST_SHFRAME_RX_LEN

◆ ASH_HOST_SHFRAME_TX_LEN

◆ ASH_ACKNUM_MASK

◆ ASH_RFLAG_MASK

◆ ASH_NFLAG_MASK

◆ ASH_PFLAG_MASK

◆ ASH_FRMNUM_MASK

◆ MOD8

◆ INC8