AN2038

Function description

17/23

Interrupt Service Routine

Function Name

Input Parameter

Return Value

Reset_TIMER

void

void

Description

Reset and Freeze the timer. It is called after a validation of Start Condition.

Function Name

Input Parameter

Return Value

Start_TIMER

void

void

Description

UnFreeze the Timer. It is called when a falling of SDA occurs when SCL is high (Start Condition)

Function Name

Input Parameter

Return Value

TIMER_A_Interrupt_Routine

void

void

Description

Timeout interrupt service routine.

It is used to reset the state if a Start Condition is not validated.

The ISR will be executed TIMEOUT microseconds (defined in I2C.h) after the "Start_TIMER"

command; usually the timer start after a falling of SDA while SCL is high (Start Condition event).

If TIMEOUT occurs without a valid clock impulse the status came back to WAIT_START and the

timer will be reinitialized (freeze) in this case the Start Condition is not validated.

Function Name

Input Parameter

Return Value

SPI_Interrupt_Routine

void

void

Description

ISR executed each SPI end of transmission.

If the received byte is the first byte after the Start Condition, the slave check if it is addressed (the

SLAVE_ADDRESS is defined in the I2C.h). If it is addressed, acknowledge will be sent, in the same

time the flags SLAVE_READ or SLAVE_WRITE will be set according the 8th bit (R/W bit).

Otherwise,

if SLAVE is reading (SLAVE_READ is true) the data is stored in I2C_Datas_R and acknowledge will

be sent;

if SLAVE is writing (SLAVE_WRITE is true) set SLAVE_WAIT_MSACK flag. SPI is disabled and the

micro is waiting for the next clock to validate the master acknowledge.