Datasheet

Section 8 EXDMA Controller (EXDMAC)
R01UH0309EJ0500 Rev. 5.00 Page 431 of 1408
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
8.4.5 Transfer Modes
There are two transfer modes: normal transfer mode and block transfer mode. When the activation
source is an external request, either normal transfer mode or block transfer mode can be selected.
When the activation source is an auto request, normal transfer mode is used.
(1) Normal Transfer Mode
In normal transfer mode, transfer of one transfer unit is processed in response to one transfer
request. EDTCR functions as a 24-bit transfer counter.
The ETEND signal is output only for the last EXDMA transfer. The EDRAK signal is output each
time a transfer request is accepted and transfer processing is started.
Figure 8.7 shows examples of EXDMA transfer timing in normal transfer mode.
Read Write Read Write
EXDMA
transfer cycle
Last EXDMA
transfer cycle
Bus cycle
ETEND
Transfer conditions:
Dual address mode, auto request mode
EXDMA EXDMA
EDRAK
EDREQ
Bus cycle
EDACK
Transfer conditions:
Single address mode, external request mode
Figure 8.7 Examples of Timing in Normal Transfer Mode