M16C62M Datasheet, PDF (18/25 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Usage precaution
Mitsubishi microcomputers
M16C / 62M (80-pin version) Group
(Low voltage version)
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Timer B (pulse period/pulse width measurement mode)
(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.
A-D Converter
(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.
Stop Mode and Wait Mode
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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”.
Interrupts
(1) Reading address 0000016
• When maskable interrupt is occurred, CPU read the interrupt information (the interrupt number
and interrupt request level) in the interrupt sequence.
The interrupt request bit of the certain interrupt written in address 0000016 will then be set to “0”.
Reading address 0000016 by software sets enabled highest priority interrupt source request bit to “0”.
Though the interrupt is generated, the interrupt routine may not be executed.
Do not read address 0000016 by software.
(2) Setting the stack pointer
• The value of the stack pointer immediately after reset is initialized to 000016. Accepting an
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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