AN1105 datasheet(44/100 Pages) STMICROELECTRONICS

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ST7 pCAN PERIPHERAL DRIVER

typedef enum {CAN_FILTER_MATCH,CAN_FILTER_NO_MATCH}CAN_Filter_Status;

Return values of the software filtering routine.

typedef enum {ITERR,ITRECEPT,ITTRANSMIT,ITSCIF}IT_Type;

Return values of the routine that determines which IT has to be processed first.

typedef enum

{CAN_CLEAN_FATAL,CAN_CLEAN_SUCCESS,CAN_CLEAN_FAILURE}CAN_Clean_Error;

Return values of the Cleaning function.

3.2.1.4 Status Counter

static u8 status_counter=0;

This is a variable used by the Sleep function to determine the state of the reception and trans-

mission registers. It is updated the following way:

– +1, when a reception IT is taken into account

– -1, when a reception buffer is released

– +1, when a message is put into the transmission queue

– -1, when a message is sent (in the IT function)

When the CAN_Sleep function is called, a simple test of this variable lets the driver know if

there are still pending jobs and if the Sleep operation must be cancelled.

3.2.2 Internal Routines

3.2.2.1 Static CAN_Filter_Status CAN_Filter(u16 ident_code)

Performs a classical dichotomy algorithm and compares the value given as parameter with the

contents of the i_filters array.

INPUT

CAN message identifier

OUTPUT

Error status

DESCRIPTION

Tests matching of IDs of received messages and software filters.

Possible returned status: CAN_FILTER_MATCH and CAN_FILTER_NO_MATCH

COMMENTS

Called by CAN_Receive

Compiled only if FILTERS_ENABLED is set.

Priority is given here to SPEED, that’s why the code may look strange.

AN1105 датащи(PDF) 44 Page - STMicroelectronics