STM8S datasheet(406/467 Pages) STMICROELECTRONICS

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Controller area network (beCAN)

RM0016

406/467

DocID14587 Rev 14

23.11.5

CAN receive FIFO register (CAN_RFR)

Address offset: 0x04

Reset value: 0x00

654

3210

Reserved

RFOM

FOVR

FULL

Reserved

FMP[1:0]

rrs

rc_w1

Bit 7:6 Reserved.

Bit 5 RFOM Release FIFO Output Mailbox

Set by software to release the output mailbox of the FIFO. The output mailbox can only be released

when at least one message is pending in the FIFO. Setting this bit when the FIFO is empty has no

effect. If more than one message is pending in the FIFO, the software has to release the output

mailbox to access the next message.

Cleared by hardware when the output mailbox has been released.

Bit 4 FOVR FIFO Overrun

This bit is set by hardware when a new message has been received and passed the filter while the

FIFO was full.

This bit is cleared by software writing ‘1’.

Bit 3 FULL FIFO Full

Set by hardware when three messages are stored in the FIFO.

This bit can be cleared by software writing ‘1’ or by releasing the FIFO by means of RFOM.

Bit 2 Reserved.

Bits 1:0 FMP[1:0] FIFO Message Pending

These bits indicate how many messages are pending in the receive FIFO.

FMP is increased each time the hardware stores a new message in to the FIFO. FMP is decreased

each time the FIFO output mailbox has been released by hardware (RFOM bit has been cleared

after prior setting by software).

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