Datasheet

Section 8 EXDMA Controller (EXDMAC)
R01UH0309EJ0500 Rev. 5.00 Page 423 of 1408
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
8.4 Operation
8.4.1 Transfer Modes
The transfer modes of the EXDMAC are summarized in table 8.2.
Table 8.2 EXDMAC Transfer Modes
Address Registers
Transfer Mode
Transfer
Origin
Number of
Transfers
Source Destination
Auto request mode
• Burst/cycle steal
mode
Auto
request
Normal
transfer
mode
External request
mode
• Cycle steal mode
External
request
1 to
16,777,215
or no
specification
Dual
address
mode
Block
transfer
mode
External request
mode
• Burst transfer of
specified block
size for a single
transfer request
• Block size: 1 to
256 bytes or
words
External
request
1 to 65,535
or no
specification
EDSAR EDDAR
Single
address
mode
• Direct data transfer to/from external device using
EDACK pin instead of source or destination address
register
• Above transfer mode can be specified in addition to
address register setting
• One transfer possible in one bus cycle
(Transfer mode variations are the same as in dual
address mode.)
EDSAR/
EDACK
EDACK/
EDDAR
The transfer mode can be set independently for each channel.
In normal transfer mode, a one-byte or one-word transfer is executed in response to one transfer
request. With auto requests, burst or cycle steal transfer mode can be set. In burst transfer mode,
continuous, high-speed transfer can be performed until the specified number of transfers have
been executed or the transfer enable bit is cleared to 0.