Mitsubishi microcomputers
M16C / 61 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Clock Generating Circuit
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) functions
provided an external clock is selected. Table 1.12.2 shows the status of the ports in stop mode.
Stop mode is cancelled by a hardware reset or interrupt. If an interrupt is to be used to cancel stop mode,
that interrupt must first have been enabled.
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 1.12.2. Port status during stop mode
Pin
Memory expansion mode
Microprocessor mode
Single-chip mode
_______
_______
Address bus, data bus, CS0 to CS3
_____ ______ ________ ________ _________
RD, WR, BHE, WRL, WRH
__________
Retains status before stop mode
“H”
HLDA, BCLK
“H”
“H”
ALE
Port
Retains status before stop mode Retains status before stop mode
Valid only in single-chip mode “H”
CLKOUT
When fC selected
When f8, f32 selected
Valid only in single-chip mode Retains status before stop mode
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MITSUBISHI [ Mitsubishi Group ]
