M16C30L Datasheet, PDF (39/166 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Clock Generating Circuit
Mitsubishi microcomputers
M16C / 30L Group
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) functions
provided an external clock is selected. Table 1.10.2 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
_______
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.
The main clock division select bit 0 (bit 6 at address 000616) changes to “1” when shifting from high-speed/
medium-speed mode to stop mode, shifting to low power dissipation mode and at reset. When shifting from
high-speed/medium-speed mode to low-speed mode, the value before high-speed/medium-speed mode is
retained.
Table 1.10.2. Port status during stop mode
Pin
_______
_______
Address bus, data bus, CS0 to CS3,
________
BHE
_____ ______ ________ _________
RD, WR, WRL, WRH
__________
HLDA, BCLK
ALE
Port
CLKOUT When fc selected
When f8, f32 selected
Memory expansion mode
Microprocessor mode
Retains status before stop mode
Single-chip mode
“H”
“H”
“H”
Retains status before stop mode Retains status before stop mode
Valid only in single-chip mode “H”
Valid only in single-chip mode Retains status before stop mode
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