M16CSLASH1N datasheet(164/238 Pages) RENESAS

164 / 238 page

Rev.1.00

Oct 20, 2004

page 152 of 222

M16C/1N Group

16. CAN Module

REJ09B0007-0100Z

16.12.1 Reception

Figure 16.24 shows the behavior of the module when receiving two consecutive CAN messages.

Figure 16.24 Timing of Receive Data Frame Sequence

(1) On monitoring a SOF on the bus the RecState bit becomes active immediately, given the module

has no transmission pending (see section "16.12.2 Transmission" below).

(2) After successful reception of the message the NewData bit of the receiving slot becomes active.

The InvalData bit becomes active at the same time and becomes inactive again after the complete

message was transferred to the slot.

(3) When the bit in the C0ICR register of the receiving slot is active the receive successful interrupt is

requested and the C0STR register changes. It shows the slot number where the message was

stored and the RecSucc bit is active.

(4) Read the message out of the slot after setting the New Data bit to “0” by a program.

(5) If the NewData bit is set to "0" by a program or the next CAN message is received successfully

before the reception request for the slot is canceled, the MsgLost bit is set to "1". The new received

message is transferred to the slot. The interrupt request and the C0STR register change like (3).

CANbus

RecReq

InvalData

Succ.Rec Int.

RecState

RecSucc

MBOX

NewData

SOF

ACK

EOF

IFS

SOF

Receive slot No.

MsgLost

(1)

(2)

(3)

(4)

(5)

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