E62655RUSB Renesas Electronics America, E62655RUSB Datasheet - Page 313

• Manufacturer Part Number: E62655RUSB
• Description: EMULATOR BASE H8S/2655R W/USB
• Manufacturer: Renesas Electronics America
• Type: Microcontrollerr

Specifications of E62655RUSB

• Contents: E6000 Emulator Unit and 4 Logic Probes
• For Use With/related Products: H8S/2655R
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Section 7 DMA Controller
When using the DMAC for single address mode reading, transfer is performed from external
memory to the external device, and the DACK pin functions as a write strobe for the external
device. When using the DMAC for single address mode writing, transfer is performed from the
external device to external memory, and the DACK pin functions as a read strobe for the external
device. Since there is no directional control for the external device, one or other of the above
single directions should be used.
Bus cycles in single address mode are in accordance with the settings of the bus controller for the
external memory area. On the external device side, DACK is output in synchronization with the
address strobe. For details of bus cycles, see section 7.5.11, DMAC Bus Cycles (Single Address
Mode).
Do not specify internal space for transfer addresses in single address mode.
7.5.9
Basic DMAC Bus Cycles
An example of the basic DMAC bus cycle timing is shown in figure 7.18. In this example, word-
size transfer is performed from 16-bit, 2-state access space to 8-bit, 3-state access space. When the
bus is transferred from the CPU to the DMAC, a source address read and destination address write
are performed. The bus is not released in response to another bus request, etc., between these read
and write operations. As with CPU cycles, DMA cycles conform to the bus controller settings.
CPU cycle
DMAC cycle (1-word transfer)
CPU cycle
T
T
T
T
T
T
T
T
1
2
1
2
3
1
2
3
Source
Destination address
address
Address bus
RD
HWR
LWR
Figure 7.18 Example of DMA Transfer Bus Timing
The address is not output to the external address bus in an access to on-chip memory or an internal
I/O register.
Rev. 5.00 Sep 14, 2006 page 283 of 1060
REJ09B0331-0500