Rev.2.00 Oct 16, 2006 page 245 of 354
REJ09B0340-0200
M30245 Group
2. DMAC
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 2.10.5 shows an example of operation and Figure 2.10.6
shows the set-up procedure.
2.10.2 Operation of DMAC (one-shot transfer mode)
Figure 2.10.5. Example of operation of one-shot transfer mode
Dummy
cycle
Source
Source
Dummy
cycle
Dummy
cycle
BCLK
Address bus
RD signal
WR signal
Data bus
DMAi
request bit
DMA transfer
counter
DMAi
interrupt
request bit
DMAi
enable bit
Write signal to
software DMAi
request bit
CPU use
Source
Source
Dummy
cycle
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
accepted, or cleared by software
(2) Data transfer begins
CPU use
CPU use
FF
16
(3) Underflow
CPU use
CPU use
CPU use
Destination
Destination
Destination
Destination
01
16
Table 2.10.1. Choosed functions
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
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.
Содержание M16C FAMILY
Страница 12: ...Chapter 1 Hardware...
Страница 13: ...See M30245 group datasheet...
Страница 14: ...Chapter 2 Peripheral Functions Usage...
Страница 303: ...THIS PAGE IS BLANK FOR REASONS OF LAYOUT...
Страница 304: ...Chapter 3 Examples of Peripheral Functions Applications...
Страница 340: ...Chapter 4 External Buses...
Страница 361: ...THIS PAGE IS BLANK FOR REASONS OF LAYOUT...
Страница 362: ...Chapter 5 Standard Characteristics...
Страница 369: ...1753 Shimonumabe Nakahara ku Kawasaki shi Kanagawa 211 8668 Japan M30245 Group REJ09B0340 0200 User s Manual...