Mitsubishi microcomputers
M30220 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Usage precaution
153
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)
(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.
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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”.
(3) When the MCU running in low-speed or low power dissipation mode, do not enter WAIT mode with
WAIT peripheral function clock stop bit set to “1”.
(1) Make sure timer Ai for real time port output is set for timer mode, and is set to have “no gate function”
using the gate function select bit.
(2) Before setting the real time port mode select bit to “1”, temporarily turn off the timer Ai used and write
its set value to the timer Ai register.
Real time port
Serial I/O
When the IIC mode select bit (bit 0 at address 037716) is set to “1”;
(1) When setting up port P7 (address 03EF16), write immediate values. If you use Read/Modify/Write
instructions (BSET, BCLR, AND, OR, etc..) on the port P7 direction register, the value of P71 direction
register may change to unknown data.
(2) Only for the mask ROM version, when the internal/external clock select bit (bit 3 of address 037816) is
set to “1 (set to slave)”, the SCL wait output bit (bit 2 of address 037616) and SCL wait output bit 2 (bit
5 of address 037616) do not function.
(3) Only for the mask ROM version, when the internal/external clock select bit (bit 3 of address 037816) is
set to “1 (set to slave)”, the port P71 cannot be read unless the port P71 direction register (bit 1 of
address 03EF16) is set to “0”, although it is specified as follows; “When IICM=1, the port pin shall be
able to be read even if the P71 direction register=1.”