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Rev.1.02 Jul 01, 2005 page 219 of 314
REJ09B0126-0102
M16C/6N Group (M16C/6NL, M16C/6NN) 18. CAN Module
Under development
This document is under development and its contents are subject to change.
18.15 Reception and Transmission
Table 18.3 shows configuration of CAN reception and transmission mode.
Table 18.3 Configuration of CAN Reception and Transmission Mode
TrmReq, RecReq, Remote, RspLock, RemActive, RspLock: Bits in C0MCTLj register (j = 0 to 15)
When configuring a slot as a reception slot, note the following points.
(1) Before configuring a slot as a reception slot, be sure to set the C0MCTLj register to “00h”.
(2) A received message is stored in a slot that matches the condition first according to the result of reception
mode configuration and acceptance filtering operation. Upon deciding in which slot to store, the smaller
the number of the slot is, the higher priority it has.
(3) In normal CAN operation mode, when a CAN module transmits a message of which ID matches, the
CAN module never receives the transmitted data. In loop back mode, however, the CAN module
receives back the transmitted data. In this case, the module does not return ACK.
When configuring a slot as a transmission slot, note the following points.
(1) Before configuring a slot as a transmission slot, be sure to set the C0MCTLj registers to “00h”.
(2) Set the TrmReq bit in the C0MCTLj register to “0” (not transmission slot) before rewriting a transmission slot.
(3) A transmission slot should not be rewritten when the TrmActive bit in the C0MCTLj register is “1”
(transmitting).
If it is rewritten, an indeterminate data will be transmitted.
TrmReq RecReq Remote RspLock Communication Mode of Slot
0 0 - - Communication environment configuration mode:
configure the communication mode of the slot.
0 1 0 0 Configured as a reception slot for a data frame.
1 0 1 0 Configured as a transmission slot for a remote frame.
(At this time the RemActive = 1.)
After completion of transmission, this functions as a reception
slot for a data frame. (At this time the RemActive = 0.)
However, when an ID that matches on the CAN bus is detected
before remote frame transmission, this immediately functions
as a reception slot for a data frame.
1 0 0 0 Configured as a transmission slot for a data frame.
0 1 1 1/0 Configured as a reception slot for a remote frame.
(At this time the RemActive = 1.)
After completion of reception, this functions as a transmission
slot for a data frame. (At this time the RemActive = 0.)
However, transmission does not start as long as RspLock bit
remains “1”; thus no automatic response.
Response (transmission) starts when the RspLock bit is set to “0”.