
358
DMAC
M
i
t
s
u
M
S
b
i
s
3
M
h
0
I
C
i
m
2
R
i
1
O
c
r
8
C
o
c
o
G
M
m
p
r
P
u
t
u
T
e
r
p
R
s
o
U
S
I
N
G
L
E
-
C
H
I
P
1
6
-
B
I
T
C
M
O
O
E
In one-shot transfer mode, choose functions from the items shown in Table 2.10.1. Operations of the
circled items are described below. Figure 2.10.4 shows an example of operation and Figure 2.10.5
shows the set-up procedure.
Table 2.10.1. Choosed functions
2.10.2 Operation of DMAC (one-shot transfer mode)
Figure 2.10.4. Example of operation of one-shot transfer mode
Operation (1) When software trigger is selected, setting software DMA request bit to “1” generates a DMA
transfer request signal.
(2) If DMAC is active, data transfer starts, and the contents of the address indicated by the DMAi
forward-direction address pointer are transferred to the address indicated by the DMAi desti-
nation pointer. When data transfer starts directly after DMAC becomes active, the value of
the DMAi transfer counter reload register is reloaded to the DMAi transfer counter, and the
value of the DMAi source pointer is reloaded by the DMAi forward-direction address pointer.
Each time a DMA transfer request signal is generated, 1 byte of data is transferred. The
DMAi transfer counter is down counted, and the DMAi forward-direction address pointer is up
counted.
(3) If the DMA transfer counter underflows, the DMA enable bit changes to “0” and DMA transfer
is completed. The DMA interrupt request bit changes to “1” simultaneously.
Item
Transfer space
Unit of transfer
Set-up
O
O
Fixed address from an arbitrary 1 M bytes space
Arbitrary 1 M bytes space from a fixed address
Fixed address from fixed address
8 bits
16 bits
Dummy
Source
Source
Dummy
Dummy
cycle
BCLK
Address bus
RD signal
WR signal
Data bus
DMAi
DMA transfer
DMAi
request bit
DMAi
Write signal to
CPU use
Source
Source
Dummy
Indeterminate
00
16
In the case in which the number of transfer times is set to 2.
(1) Request signal for a DMA transfer occurs
Cleared to “0” when interrupt request is
(2) Data transfer begins
CPU use
CPU use
FF
16
(3) Underflow
CPU use
CPU use
CPU use
Destination
Destination
Destination
Destination
01
16