HD6417750 Datasheet, PDF (554/1039 Pages) Renesas Technology Corp – SuperH RISC engine

Bit 19—'5(4 Select (DS): Specifies either low level detection or falling edge detection as the
sampling method for the '5(4 pin used in external request mode.
In normal DMA mode, this bit is valid only in CHCR0 and CHCR1. In DDT mode, it is valid in
CHCR0–CHCR3.
Bit 19: DS
Description
0
Low level detection
1
Falling edge detection
Note: Level detection burst mode when TM = 1 and DS = 0
Edge detection burst mode when TM = 1 and DS = 1
(Initial value)
Bit 18—Request Check Level (RL): Selects whether the DRAK signal (that notifies an external
device of the acceptance of '5(4) is an active-high or active-low output.
In normal DMA mode, this bit is valid only in CHCR0 and CHCR1. In DDT mode, this bit is
invalid.
Bit 18: RL
0
1
Description
DRAK is an active-high output
DRAK is an active-low output
(Initial value)
Bit 17—Acknowledge Mode (AM): In dual address mode, selects whether DACK is output in the
data read cycle or write cycle. In single address mode, DACK is always output regardless of the
setting of this bit.
In normal DMA mode, this bit is valid only in CHCR0 and CHCR1. In DDT mode, this bit is
valid for CHCR1 to CHCR3 in the SH7750. In the SH7750S, this bit is valid for CHCR0 to
CHCR3. (DDT mode: 7'$&.)
Bit 17: AM
0
1
Description
DACK is output in read cycle
DACK is output in write cycle
(Initial value)
Rev. 6.0, 07/02, page 502 of 986