Operation; Transfer Modes - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

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
Transfer Mode
Dual Normal
address transfer
mode mode
Block
transfer
mode
•
Single
Direct data transfer to/from external device using
address
('$&. pin instead of source or destination address
mode
register
•
Above transfer mode can be specified in addition to
address register setting
•
One transfer possible in one bus cycle
(Transfer mode variations are the same as in dual address
mode.)
The transfer mode can be set independently for each channel.
In normal transfer mode, a one-byte or one-word transfer is executed in response to one transfer
request. With auto requests, burst or cycle steal transfer mode can be set. In burst transfer mode,
continuous, high-speed transfer can be performed until the specified number of transfers have
been executed or the transfer enable bit is cleared to 0.
Auto request mode
•
Burst/cycle steal
mode
External request
mode
•
Cycle steal mode
External request
mode
•
Burst transfer of
specified block
size for a single
transfer request
•
Block size: 1 to
256 bytes or
words
Transfer Number of
Origin Transfers
Auto 1 to
request 16,777,215
or no
specification
External
request
External 1 to 65,535
request or no
specification
Address Registers
Source Destination
EDSAR EDDAR
('$&./
EDSAR/
('$&.
EDDAR
Rev. 1.0, 09/01, page 331 of 904