D M A c h a n n e l r e g i s t e r s

Bits

Access

Mnemonic

Reset

Description

 

 

 

 

REQ continued

 

 

DMA channels 4/6 interface with an external

 

 

 

 

peripheral using handshaking signals multiplexed

 

 

 

 

through PORTC.

 

 

 

 

When REQ is set to 0 in DMA channel 4 and

 

 

 

 

set to 1 in DMA channel 6, DMA channel 6 is

 

 

 

 

tied to the external DMA port through PORTC.

 

 

 

 

When REQ is set to 1 in DMA channel 4, that

 

 

 

 

channel is tied to the external DMA port

 

 

 

 

through PORTC, no matter the REQ bit setting

 

 

 

 

in DMA channel 6.

 

 

 

 

These bits should not be set in any channels other

 

 

 

 

than DMA 3, 4, 5, or 6.

 

 

 

 

 

D22

N/A

Reserved

N/A

N/A

 

 

 

 

 

D21

R/W

SINC_

0

Source address increment

 

 

 

 

0 Increment source address pointer

 

 

 

 

1 Do not increment source address pointer

 

 

 

 

Controls whether the source address pointer is

 

 

 

 

incremented after each DMA transfer. The DMA

 

 

 

 

controller uses this bit in all modes when referring

 

 

 

 

to a memory address. This bit is ignored when the

 

 

 

 

source is a fly-by port.

 

 

 

 

 

D20

R/W

DINC_

0

Destination address increment

 

 

 

 

0 Increment destination address pointer

 

 

 

 

1 Do not increment destination address pointer

 

 

 

 

Controls whether the destination address pointer is

 

 

 

 

incremented after each DMA transfer. The DMA

 

 

 

 

controller uses this bit in all modes when referring

 

 

 

 

to a memory address. This bit is ignored when the

 

 

 

 

destination is a fly-by port.

 

 

 

 

For memory-to-memory operation with DINC_=0,

 

 

 

 

the data is written to the specified destination

 

 

 

 

address and all subsequent data are written are

 

 

 

 

written to the specified destination address+4.

 

 

 

 

 

D19:18

N/A

Reserved

N/A

N/A

Table 50: DMA Control register bit definition

1 4 0

N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v . D 0 3 / 2 0 0 6

Page 154
Image 154
Digi NS7520 manual Sinc, Source address increment, Dinc, Destination address increment