DMA Request Control (DMAREQC)

16.2 DMA Request Control (DMAREQC)

The DMAREQC register provides a software-controlled connection matrix for DMA requests. It logically routes DMA requests from the DMA timers and UARTs to the four channels of the DMA controller. Writing to this register determines the exact routing of the DMA request to the four channels of the DMA modules. If DCRn[EEXT] is set and the channel is idle, the assertion of the appropriate DREQn activates channel n.

Field

Reset

R/W

Field

Reset

R/W

31

 

 

 

 

 

20

19

16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0000_0000_0000_0000

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R/W

 

 

 

 

 

 

 

 

 

 

 

15

12

11

8

7

4

3

0

 

DMAC3

 

DMAC2

 

DMAC1

 

 

DMAC0

 

 

 

 

 

 

 

 

 

0000_0000_0000_0000

R/W

IPSBAR + 0x014

Figure 16-2. DMA Request Control Register (DMAREQC)

Table 16-1. DMAREQC Field Description

Bits

Name

 

Description

 

 

 

31–16

Reserved. Should be cleared.

 

 

 

15–0

DMACn

DMA Channel n. Each four bit field defines the logical connection between the DMA requestors and that DMA

 

 

channel. There are seven possible requesters (4 DMA Timers and 3 UARTs). Any request can be routed to any

 

 

of the DMA channels. Effectively, the DMAREQC provides a software-controlled routing matrix of the 7

 

 

DMA request signals to the 4 channels of the DMA module. DMAC3 controls DMA channel 3. DMAC2

 

 

controls DMA channel 2. DMAC1 controls DMA channel 1. DMAC0 controls DMA channel 0.

 

 

1000

UART0.

 

 

1001

UART1.

 

 

1010

UART2.

 

 

0100

DMA Timer 0.

 

 

0101

DMA Timer 1.

 

 

0110

DMA Timer 2.

 

 

0111

DMA Timer 3.

 

 

All other values are reserved and will not generate a DMA request.

 

 

 

 

MOTOROLA

Chapter 16. DMA Controller Module

16-3

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Image 343
Motorola MCF5281, MCF5282 user manual DMA Request Control Dmareqc