Motorola ColdFire MCF5281 - Manual (Page 298)

DMA Controller Module
16-2 Freescale Semiconductor
NOTE
Throughout this chapter “external request” and DREQ are used to refer to a
DMA request from one of the on-chip UARTS or DMA timers. For details
on the connections associated with DMA request inputs, see
Section 16.2,
“DMA Request Control (DMAREQC) .”
16.1.1 DMA Module Features
The DMA controller module features are as follows:
• Four independently programmable DMA controller channels
• Auto-alignment feature for source or destination accesses
• Dual-address transfers
• Channel arbitration on transfer boundaries
• Data transfers in 8-, 16-, 32-, or 128-bit blocks using a 16-byte buffer
• Continuous-mode or cycle-steal transfers
• Independent transfer widths for source and destination
• Independent source and destination address registers
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.
31 20 19 16
Field — —
Reset 0000_0000_0000_0000
R/W R/W
15 12 11 8 7 4 3 0
Field DMAC3 DMAC2 DMAC1 DMAC0
Reset 0000_0000_0000_0000
R/W R/W
IPSBAR + 0x014
Figure 16-2. DMA Request Control Register (DMAREQC)
Table 16-1. DMAREQC Field Description
Bits Name Description
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3