7630 datasheet(132/238 Pages) RENESAS

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7630 Group User’s Manual

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2.4 Controller Area Network (CAN) module

2.4.13 Wake-up via CAN

The module features a function to wake-up the CPU on CAN traffic. This feature is implemented by an external

interrupt function on the P32/CRX input port. The wake-up interrupt is requested upon a recessive to dominant

edge (by start-of-frame of a message sent by another node) on the P32/CRX.

The initialization required to use the wake-up function is:

1. Clear CWKU interrupt request bit IREQB.0.

2. Set CWKU interrupt control bit ICONB.0.

3. Put module to sleep mode by setting the sleep control bit CTRM.0 (Figure 2.4.3); see section 2.4.4.

4. Set the pull transistor enable bit PUP3.2; this activates the pull transistor towards the recessive level (depend-

ing on the dominant polarity selected by PCON.1).

5. Put MCU to low-power mode (wait or stop mode).

The first frame sent by another node awakens the CPU by an CWKU interrupt request. The module should be put

to normal (run) mode again as part of the CWKU interrupt service; also the pull transistor should be disabled as

part of this interrupt service routine.

Note: The frame triggering the wake-up function can not be received and is lost.

7630 Datasheet(PDF) 132 Page - Renesas Technology Corp