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17.10 Reception and Transmission
Configuration of CAN Reception and Transmission Mode
Table 17.3 shows configuration of CAN reception and transmission mode.
Table 17.3 Configuration of CAN Reception and Transmission Mode
TrmReq RecReq Remote RspLock
0
0
0
1
1
0
1
0
0
1
TrmReq, RecReq, Remote, RspLock, RemActive, RspLock: Bits in the 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 (j = 0 to 15) to 00
(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 operating 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 00
(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 undefined data will be transmitted.
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0
1
0
1
0 -
1
1
2
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-
Communication environment configuration mode:
configure the communication mode of the slot.
0
0
Configured as a reception slot for a data frame.
1
0
Configured as a transmission slot for a remote frame. (At this time
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.
0
0
Configured as a transmission slot for a data frame.
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.
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Communication mode of the slot
the RemActive = 1.)
17. CAN Module
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