ST72561AR7-Auto datasheet(233/324 Pages) STMICROELECTRONICS

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ST72561-Auto

beCAN controller (beCAN)

Doc ID 12370 Rev 8

233/324

Although the transmission of incorrect data will not cause problems at the CAN network

level, it can severely disturb the application. A transmit mailbox can be only modified by

software while it is in empty state (refer to Figure 100).

The filters must be deactivated before their value can be modified by software. The

modification of the filter configuration (scale or mode) can be done by software only in

initialization mode.

17.7

beCAN cell limitations

17.7.1

FIFO corruption

FIFO corruption occurs in the following case:

WHEN the beCAN RX FIFO already holds two messages (that is, FMP == 2)

AND the application releases the FIFO (with the instruction CRFR = B_RFOM;)

WHILE the beCAN requests the transfer of a new receive message into the FIFO (this lasts

one CPU cycle)

THEN the internal FIFO pointer is not updated

BUT the FMP bits are updated correctly

As the FIFO pointer is not updated correctly, this causes the last message received to be

overwritten by any incoming message. This means one message is lost as shown in the

example in Figure 109. The beCAN will not recover normal operation until a device reset

occurs.

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