32186 datasheet(737/1032 Pages) RENESAS

737 / 1032 page

CAN MODULE

13-127

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

13.6 Receiving Data Frames

13.6.3 Reading Out Received Data Frames

The following shows the procedure for reading out received data frames from the slot.

(1) Clearing TRFIN (Transmit/Receive Finished) bit

Write H’4E, H’40 or H’00 to the CAN Message Slot Control Register (C0MSLnCNT, C1MSLnCNT) to clear

the TRFIN bit to "0." After this write, the slot operates as follows:

Values Written to

Slot Operation after Write

C0MSLnCNT, C1MSLnCNT

H’4E

Operates as a data frame receive slot. Whether overwritten can be verified by ML bit.

H’40

Operates as a data frame receive slot. Whether overwritten cannot be verified by ML bit.

H’00 (Note 1)

The slot stops transmit/receive operation.

Note 1: When the CAN Message Slot Control Register (C0MSLnCNT, C1MSLnCNT) RR (Recieve Request) bit is cleared to

"0" by writing H’00, if the receive operation has started until just before the bit is cleared, the transmit/receive control

will be performed until the receive operation is finished.

Note : • If message-lost check by the ML bit is needed, write H’4E to clear the TRFIN bit.

(2) Reading out from the message slot

Read out a message from the message slot.

(3) Checking TRFIN (Transmit/Receive Finished) bit

Read the CAN Message Slot Control Register to check the TRFIN (Transmit/Receive Finished) bit.

1) If TRFIN (Transmit/Receive Finished) bit = "1"

It means that new data was stored in the slot while still reading out a message from it in (2) above. In

this case, the data read out in (2) may contain an undefined value. Therefore, reexecute the above

procedure beginning with clearing of the TRFIN (Transmit/Receive Finished) bit in (1).

2) If TRFIN (Transmit/Receive Finished) bit = "0"

It means that the CAN module finished reading out from the slot normally.

32186 Datasheet(PDF) 737 Page - Renesas Technology Corp