Usage precaution

Mitsubishi microcomputers

M16C / 62M Group

(Low voltage version)

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

24

Stop Mode and Wait Mode

A-D Converter

(1) If changing the measurement mode select bit is set after a count is started, the timer Bi interrupt

request bit goes to “1”.

(2) When the first effective edge is input after a count is started, an indeterminate value is transferred to

the reload register. At this time, timer Bi interrupt request is not generated.

Timer B (pulse period/pulse width measurement mode)

Interrupts

(1) Write to each bit (except bit 6) of A-D control register 0, to each bit of A-D control register 1, and to bit

0 of A-D control register 2 when A-D conversion is stopped (before a trigger occurs).

In particular, when the Vref connection bit is changed from “0” to “1”, start A-D conversion after an

elapse of 1

µs or longer.

(2) When changing A-D operation mode, select analog input pin again.

(3) Using one-shot mode or single sweep mode

Read the correspondence A-D register after confirming A-D conversion is finished. (It is known by A-

D conversion interrupt request bit.)

(4) Using repeat mode, repeat sweep mode 0 or repeat sweep mode 1

Use the undivided main clock as the internal CPU clock.

• When maskable interrupt is occurred, CPU read the interrupt information (the interrupt number

and interrupt request level) in the interrupt sequence.

Though the interrupt is generated, the interrupt routine may not be executed.

(2) Setting the stack pointer

interrupt before setting a value in the stack pointer may become a factor of runaway. Be sure to

set a value in the stack pointer before accepting an interrupt.

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When using the NMI interrupt, initialize the stack point at the beginning of a program. Concerning

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the first instruction immediately after reset, generating any interrupts including the NMI interrupt is

prohibited.

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(3) The NMI interrupt

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• The NMI interrupt can not be disabled. Be sure to connect NMI pin to Vcc via a pull-up resistor if

unused.

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• Do not get either into stop mode with the NMI pin set to “L”.

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(1) When returning from stop mode by hardware reset, RESET pin must be set to “L” level until main clock

oscillation is stabilized.

(2) When switching to either wait mode or stop mode, instructions occupying four bytes either from the

WAIT instruction or from the instruction that sets the every-clock stop bit to “1” within the instruction

queue are prefetched and then the program stops. So put at least four NOPs in succession either to

the WAIT instruction or to the instruction that sets the every-clock stop bit to “1”.