deveopmen
Rev.B2 for proof reading
Usage precaution
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
340
(3) External interrupt
Edge sense
Either an
“
L
”
level or an
“
H
”
level of at least 250 ns width is necessary for the signal input to pins
INT
0
to INT
5
regardless of the CPU operation clock.
Level sense
Either an
“
L
”
level or an
“
H
”
signal input to pins INT
0
to INT
5
regardless of the CPU operation clock. (When X
IN
=30MHz and
no division mode, at least 233 ns width is necessary.)
When the polarity of the INT
0
to INT
5
pins is changed, the interrupt request bit is sometimes set to
"1". After changing the polarity, set the interrupt request bit to "0". Figure 1.31.2 shows the
procedure for changing the INT interrupt generate factor.
Set the polarity select bit
Clear the interrupt request bit to
“
0
”
Set the interrupt priority level to level 1 to 7
(Enable the accepting of INTi interrupt request)
Set the interrupt priority level to level 0
(Disable
INTi
interrupt)
Figure 1.31.2. Switching condition of INT interrupt request
(4) Rewrite the interrupt control register
When a instruction to rewrite the interrupt control register is executed but the interrupt is dis-
abled, the interrupt request bit is not set sometimes even if the interrupt request for that register
has been generated. This will depend on the instructions. If this creates problems, use the below
instructions to change the register.
Instructions : AND, OR, BCLR, BSET
DMAC
(1) Do not clear the DMA request bit of the DMAi request cause select register.
In M32C/83, when a DMA request is generated while the channel is disabled (Note), the DMA trans-
fer is not executed and the DMA request bit is cleared automatically.
Note :The DMA is disabled or the transfer count register is "0".
(2) When DMA transfer is done by a software trigger, set DSR and DRQ of the DMAi request cause
select register to "1" simultaneously using the OR instruction.
e.g.) OR.B #0A0h, DMiSL
; DMiSL is DMAi request cause select register
(3) When changing the DMAi request cause select bit of the DMAi request cause select register, set "1"
to the DMA request bit, simultaneously. In this case, disable the corresponding DMA channel to
disabled before changing the DMAi request cause select bit. To enable DMA at least 8+6xN cycles
(N: enabled channel number) following the instruction to write to the DMAi request cause select
register are needed.