Section 13 Controller Area Network (HCAN)
Rev. 3.00 Mar. 14, 2006 Page 484 of 804
REJ09B0104-0300
13.4 Operation
13.4.1
Hardware and Software Resets
The HCAN can be reset by a hardware reset or software reset.
•
Hardware Reset
At power-on reset or a transition to software standby mode, the HCAN is initialized by
automatically setting the MCR reset request bit (MCR0) in MCR and the reset state bit (GSR3)
in GSR. At the same time, all internal registers, except for message control and message data
registers, are initialized by a hardware reset.
•
Software Reset
The HCAN can be reset by setting the MCR reset request bit (MCR0) in MCR via software. In
a software reset, the error counters (TEC and REC) are initialized, however other registers are
not. If bit MCR0 is set while the CAN controller is performing a communication operation
(transmission or reception), the initialization state is not entered until message transfer has
been completed. The reset status bit (GSR3) in GSR is set on completion of initialization.
13.4.2 Initialization
after Hardware Reset
After a hardware reset, the following initialization processing should be carried out:
1. Clearing of bit IRR0 in the interrupt register (IRR)
2. Bit rate setting
3. Mailbox transmit/receive settings
4. Mailbox (RAM) initialization
5. Message transmission method setting
These initial settings must be made while the HCAN is in bit configuration mode. Configuration
mode is a state in which bit GSR3 in GSR is set to 1 by a reset. Configuration mode is exited by
clearing bit MCR0 in MCR to 0; when bit MCR0 is cleared to 0, the HCAN automatically clears
bit GSR3 in GSR. There is a delay between clearing bit MCR0 and clearing bit GSR3 because the
HCAN needs time to be internally reset. After the HCAN exits configuration mode, the power-up
sequence begins, and communication with the CAN bus is possible as soon as 11 consecutive
recessive bits have been detected.
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Содержание H8SX series
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