AN2168 Freescale Semiconductor / Motorola, AN2168 Datasheet - Page 7

Manufacturer Part Number

AN2168

Description

ColdFire Microprocessor DMA Controller Application Note

Manufacturer

Freescale Semiconductor / Motorola

Datasheet

1.AN2168.pdf (28 pages)

Dual Address Mode

Example 2

AN2168

MOTOROLA

DSR = 0x01 ; clear status register

SAR = 0xFFE00400 ; source address = 0xFFE00400

DAR = 0x20000000 ; destination address = 0x20000000

BCR = 0x0002 ; transfer 2 bytes

DCR = 0x006D ; source = 16-bit, destination = 16-bit

Figure 4. Dual Address Transfer, SSIZE = word, DSIZE = word

To achieve a higher DMA transfer rate, the DMA settings from the

example in

the destination size is also word. Use the following DMA settings:

and the same chip select settings.

Figure 4

set to word. Just as before, there is a single read from the source

address, but now there is a word burst to a byte port at the destination

address. Since CS1 is programmed to allow bursts and the DMA

requests a transfer size larger than the chip select’s port size, a burst

transfer results.

shows the DMA transfer with the source and destination both

Dual Address Mode Example 1

Dual and Single Address Modes

could be changed so that

Application Note