deveopmen
Usage precaution
Preliminary Specifications REV.B
Specifications in this manual are tentative and subject to change.
Mitsubishi microcomputers
M16C/80 (144-pin version) group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
208
Example 3)
fset
nop
nop
nop
I
; Set I flag ( interrupt enabled)
; 1st instruction
; 2nd instruction
; 3rd instruction
Example 4)
ldipl
nop
nop
nop
#0
; Rewrite IPL to a smaller value
; 1st instruction
; 2nd instruction
; 3rd instruction
DMAC
(1) Do not clear the DMA request bit of the DMAi request cause select register.
In M16C/80, when a DMA request is generated while the channel is disabled (Note), the DMA transfer
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, the corresponding DMA channel is set to disabled.
At least 2 instructions are needed from the instruction to write to the DMAi request cause select bit to
enable DMA.
Example) When DMA request cause is changed to timer A0 and using DMA0 in single transfer
after DMA initial setting
push.w
R0
; Store R0 register
stc
DMD0, R0
; Read DMA mode register 0
and.b
#11111100b, R0L
; Clear DMA0 transfer mode select bit to "00"
ldc
R0, DMD0
;
DMA0 disabled
mov.b
#10000011b, DM0SL
;
Select timer A0
;
(Write "1" to DMA request bit simultaneously)
mov.b
R0L, R0L
; Dummy cycle
or.b
#00000001b, R0L
; Set DMA0 single transfer
ldc
R0, DMD0
;
DMA0 enabled
pop.w
R0
; Restore R0 register
Noise
(1) A bypass capacitor should be inserted between Vcc-Vss line for reducing noise and latch-up
Connect a bypass capacitor (approx. 0.1
μ
F) between the Vcc and Vss pins using short wiring and
thicker circuit traces.
At least 2 instructions
are needed until DMA
enabled.
Do not set address match interrupt
during this period
Do not set address match interrupt
during this period