Table 14.4 Selecting External Request Mode With Rs Bits - Hitachi SH7751 Hardware Manual

Table 14.4 Selecting External Request Mode with RS Bits

RS3 RS2 RS1
0 0 0
1


External Request Acceptance Conditions
1. When at least one of DMAOR.DME and CHCR.DE is 0, and DMAOR.NMIF,
DMAOR.AE, and CHCR.TE are all 0, if an external request (
input it will be held inside the DMAC until DMA transfer is either executed or canceled.
Since DMA transfer is not enabled in this case (DME = 0 or DE = 0), DMA transfer is not
initiated. DMA transfer is started after it is enabled (DME = 1, DE = 1, DMAOR.NMIF =
0, DMAOR.AE = 0, CHCR.TE = 0).
2. When DMA transfer is enabled (DME = 1, DE = 1, DMAOR.NMIF = 0, DMAOR.AE = 0,
CHCR.TE = 0), if an external request (
3. An external request (
= 1, DMAOR.AE = 1, during a power-on reset or manual reset, in deep sleep mode,
standby mode, or while the DMAC is in the module standby state.
4. A previously input external request will be canceled by the occurrence of an NMI interrupt
(DMAOR.NMIF = 1) or address error (DMAOR.AE = 1), or by a power-on reset or
manual reset.


Usage Notes
1. An external request (
external request (
an external device after a power-on reset or manual reset.
When DMA transfer is restarted, check whether a DMA transfer request is being held.


2. With edge detection, an accepted external request can be canceled by first negating


, enabling a change of setting from CHCR.DS = 1 to CHCR.DS = 0, and then


asserting
RS0 Address Mode
0 Dual address
mode
0 Single address
mode
1 Single address
mode


) will be ignored if input when CHCR.TE = 1, DMAOR.NMIF


) is detected by a low level or falling edge. Ensure that the


) signal is held high when there is no DMA transfer request from
after setting CHCR.DS to 1 again.
Transfer Source
External memory,
memory-mapped
external device, or
external device with
DACK
External memory
or memory-mapped
external device
External device with
DACK


) is input, DMA transfer is started.
Rev. 3.0, 04/02, page 487 of 1064
Transfer Destination
External memory,
memory-mapped
external device, or
external device with
DACK
External device
with DACK
External memory
or memory-mapped
external device


: edge-detected) is