M16623MC View Datasheet(PDF) -

Clock Generating Circuit

Mitsubishi microcomputers

M16C / 62A Group (80-pin)

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Clock Output

In single-chip mode, the clock output function select bits (bits 0 and 1 at address 000616) enable f8, f32, or

fc to be output from the P57/CLKOUT pin. When the WAIT peripheral function clock stop bit (bit 2 at address

000616) is set to “1”, the output of f8 and f32 stops when a WAIT instruction is executed.

Stop Mode

Writing “1” to the all-clock stop control bit (bit 0 at address 000716) stops all oscillation and the microcom-

puter enters stop mode. In stop mode, the content of the internal RAM is retained provided that VCC re-

mains above 2V.

Because the oscillation , BCLK, f1 to f32, f1SIO2 to f32SIO2, fC, fC32, and fAD stops in stop mode, peripheral

functions such as the A-D converter and watchdog timer do not function. However, timer A and timer B

operate provided that the event counter mode is set to an external pulse, and UARTi(i = 0 to 2), SI/O3,4

functions provided an external clock is selected. Table 1.9.2 shows the status of the ports in stop mode.

Stop mode is cancelled by a hardware reset or an interrupt. If an interrupt is to be used to cancel stop mode,

that interrupt must first have been enabled, and the priority level of the interrupt which is not used to cancel

must have been changed to 0. If returning by an interrupt, that interrupt routine is executed. If only a

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hardware reset or an NMI interrupt is used to cancel stop mode, change the priority level of all interrupt to

0, then shift to stop mode.

When shifting from high-speed/medium-speed mode to stop mode and at a reset, the main clock division

select bit 0 (bit 6 at address 000616) is set to “1”. When shifting from low-speed/low power dissipation mode

to stop mode, the value before stop mode is retained.

Table 1.9.2. Port status during stop mode

Pin

Single-chip mode

Port

Retains status before stop mode

CLKOUT When fc selected

“H”

When f8, f32 selected

Retains status before stop mode

30

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