M32CSLASH86 datasheet(382/505 Pages) RENESAS

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Page 359

23. CAN Module

)

(

23.2 CAN Clock

The CAN clock is the operating clock for the CAN module. f1 or fCAN can be selected as the CAN clock.

fCAN has the same frequency as the main clock. The PM25 bit in the PM2 register determines the CAN

clock. Refer to 9. Clock Generation Circuit for details.

23.2.1 Main Clock Direct Mode

fCAN becomes the CAN clock in main clock direct mode. The CAN module must enter main clock direct

mode while the PM25 bit is set to "1" (main clock). Set the PM25 bit in CAN sleep mode.

Set the PM24 bit in the PM2 register to "1" (main clock) before accessing CAN-associated registers in

main clock direct mode. Do not enter wait mode or stop mode when the PM24 bit is set to "1".

Table 23.5 lists CAN clock settings. Figure 23.36 shows a flow chart of accessing procedure for CAN-

associated registers.

Table 23.5 CAN Clock Settings

)

(

000

Figure 23.36 Accessing Procedure for CAN-Associated Registers

Start

Wait until a clock oscillation stabilized

Set the PM24 bit in the PM2 register

to "1" (main clock)

Set the PM24 bit to "0" (clock selected

by the CM07 bit in the CM0 register)

Access to CAN-associated registers

End

NOTES:

1. Waiting time varies depending on the CPU clock frequency before or after PM24 bit

setting is changed.

2 x High Frequency

Cycles

Low Frequency

- High Frequency : Higher Frequency compared "before PM24 bit setting changes" with

"after PM24 bit setting changes"

- Low Frequency : Lower Frequency compared "before PM24 bit setting changes" with

"after PM24 bit setting changes"

Waiting Time

≥

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