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Under
development
Preliminary Specifications REV.D
Specifications in this manual are tentative and subject to change.
Mitsubishi Microcomputers
M16C/80 group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Usage precaution
209
Timer B (timer mode, event counter mode)
(1) Reading the timer Bi register while a count is in progress allows reading , with arbitrary timing, the
value of the counter. Reading the timer Bi register with the reload timing gets “FFFF16”. Reading the
timer Bi register after setting a value in the timer Bi register with a count halted but before the counter
starts counting gets a proper value.
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.
(3) The value of the counter is indeterminate at the beginning of a count. Therefore, the timer Bi overflow
flag may go to “1” and timer Bi interrupt request may be generated during the interval between a count
start and an effective edge input.
Stop Mode and Wait Mode
____________
(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 shifting to WAIT mode or STOP mode, the program stops after reading from the WAIT instruc-
tion and the instruction that sets all clock stop control bits to “1” in the instruction queue. Therefore,
insert a minimum of 4 NOPs after the WAIT instruction and the instruction that sets all clock stop
control bits to “1” in order to flush the instruction queue.
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
s 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.
(5) When f(XIN) is faster than 10 MHz, make the frequency 10 MHz or less by dividing.
(6) Output impedance of sensor at A-D conversion (Reference value)
To carry out A-D conversion properly, charging the internal capacitor C shown in Figure 1.27.1 has to
be completed within a specified period of time T. Let output impedance of sensor equivalent circuit be
R0, microcomputer’s internal resistance be R, precision (error) of the A-D converter be X, and the A-
D converter’s resolution be Y (Y is 1024 in the 10-bit mode, and 256 in the 8-bit mode).