HD6417616 RENESAS [Renesas Technology Corp], HD6417616 Datasheet - Page 506

• Manufacturer Part Number: HD6417616
• Description: 32-Bit RISC Microcomputer SuperH™ RISC engine Family/SH7600 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 11 Direct Memory Access Controller (DMAC)
External Request Mode: In this mode a transfer is started by a transfer request signal (DREQn)
from an external device. Choose one of the modes shown in table 11.4 according to the application
system. When DMA transfer is enabled (DE = 1, DME = 1, TE = 0, NMIF = 0, AE = 0), a transfer
is performed upon input of a DREQn signal.
Table 11.4 Selecting External Request Modes with the TA and AM Bits
Note: * External memory, memory-mapped external device, and on-chip peripheral module
Choose to detect DREQn either by the falling edge or by level using the DS and DL bits in
CHCR0 and CHCR1 (DS = 0 is level detection, DS = 1 is edge detection; DL = 0 is active-low,
DL = 1 is active-high). The source of the transfer request does not have to be the data transfer
source or destination.
When 0 (level detection) is set to the DS bit of CHCR0 and CHCR1, set the TB bit to 0 (cycle-
steal mode) and set the TS1 and TS0 bits of CHCR0 and CHCR1 to either 00 (byte unit), 01 (word
unit), or 10 (long word unit).
When 0 is set to the DS bit of CHCR0 and CHCR1, when 1 (burst mode) is set to the TB bit of
CHCR0 and CHCR1, and when 11 (16 byte unit) is set to the TS1 and TS0 bits of CHCR1 and
CHCR1, operation is not guaranteed.
Rev. 2.00 Mar 09, 2006 page 480 of 906
REJ09B0292-0200
TA
0
1
CHCR
AM
0
1
0
1
(excluding DMAC, BSC, UBC, cache memory, E-DMAC, and EtherC).
Transfer
Address Mode
Dual address
mode
Dual address
mode
Single address
mode
Single address
mode
Acknowledge Mode
DACKn output in read
cycle
DACKn output in write
cycle
Data transferred from
memory to device
Data transferred from
device to memory
Source
Any *
Any *
External memory or
memory-mapped
external device
External device
with DACK
Destination
Any *
Any *
External device
with DACK
External memory or
memory-mapped
external device