Digi NS9215 manual A B u f f e r D e s c r i p t o r P o i n t e r, Woen

E X T E R N A L D M A

Control and Status registers

Register name	Field	Value	Comment
Output Enable Delay	WOEN	User-defined	For most applications, this field can be set to
			0.
Write Enable Delay	WWEN	User-defined	For most applications, this field can be left in
			the default state.
Write Delay	WTWR	User-defined	For most applications, this field can be left in
			the default state.
Turn Delay	WTTN	User-defined	For most applications, this field can be left in
			the default state.

C o n t r o l a n d S t a t u s r e g i s t e r s

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The external DMA configuration registers are located at base address 0xA080_0000. All the configuration registers are accessed with zero wait states.

Register address These are the external DMA control and status registers. map

Address	Description			Access	Reset value
0xA080_0000	DMA Channel	1	Buffer Descriptor Pointer	R/W	0x00000000
0xA080_0004	DMA Channel	1 Control register		R/W	0x00000000
0xA080_0008	DMA Channel	1	Status and Interrupt Enable	R/W	0x00000000
0xA080_000C	DMA Channel	1 Peripheral Chip Select		R/W	0x00000000
0xA080_0010	DMA Channel	2	Buffer Descriptor Pointer	R/W	0x00000000
0xA080_0014	DMA Channel	2 Control register		R/W	0x00000000
0xA080_0018	DMA Channel	2	Status and Interrupt Enable	R/W	0x00000000
0xA080_001C	DMA Channel	2 Peripheral Chip Select		R/W	0x00000000

D M A B u f f e r D e s c r i p t o r P o i n t e r

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Address: A080_0000, A080_0010

The DMA Buffer Descriptor Pointer register contains a 32-bit pointer to the first buffer in a contiguous list of buffer descriptors.

The external DMA module has two of these registers. Each buffer descriptor is 16 bytes in length.

346Hardware Reference NS9215