Renesas M16C Series User Manual

DMAC
M30240 Group
Rev.1.00 Sep 24, 2003 Page 259 of 360
2.7.2 Operation
2.7.2.1 One-shot transfer mode
In one-shot transfer mode, select functions from the items shown in Table 2.37. An example using the
indicated options is described below. Figure 2.103 shows an example of operation and Figure 2.104
shows the set-up procedure.
Table 2.39: DMAC in one-shot transfer mode functions
Operation
(1) When a software trigger is selected, setting the 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 for-
ward-direction address pointer are transferred to the address indicated by the DMAi destination point-
er. 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 decremented, and the
DMAi forward-direction address pointer is incremented.
(3) If the DMA transfer counter underflows, the DMA enable bit changes to “0” and the DMA transfer
is completed. The DMA interrupt request bit changes to “1” simultaneously.
Figure 2.103: Operation of one-shot transfer mode
Item
Set-up
Transfer space
O From any SFR, ROM or RAM address to a fixed address
From a fixed address to any ROM, RAM or SFR address
From one fixed address to another fixed address
Unit of transfer
O 8 bits
16 bits
Dummy
cycle
Source
Source
Dummy
cycle
Dummy
cycle
internal clock Φ
Address bus
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 0016
• 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
FF16
(3) Underflow
CPU useCPU use
CPU use
Destination Destination
Destination
Destination
0116

Renesas M16C Series Specifications

General

Brand	Renesas
Model	M16C Series
Category	Computer Hardware
Language	English