Information
:
*CHCONFIG2 = 0x00;
*CHCONFIG2 = 0xC5;
To enable a source without periodic triggering:
1. Determine with which DMA channel the source will be associated. Note that only the
first 4 DMA channels have periodic triggering capability.
2. Clear the CHCFG[ENBL] and CHCFG[TRIG] bits of the DMA channel.
3. Ensure that the DMA channel is properly configured in the DMA. The DMA channel
may be enabled at this point.
4. Select the source to be routed to the DMA channel. Write to the corresponding
CHCFG register, ensuring that the CHCFG[ENBL] is set while the CHCFG[TRIG]
bit is cleared.
To configure source #5 Transmit for use with DMA channel 2, with no periodic
triggering capability:
1. Write 0x00 to CHCFG2 (base address + 0x02).
2. Configure channel 2 in the DMA, including enabling the channel.
3. Write 0x85 to CHCFG2 (base address + 0x02).
The following code example illustrates steps 1 and 3 above:
In File registers.h:
#define DMAMUX_BASE_ADDR 0xFC084000/* Example only ! */
/* Following example assumes char is 8-bits */
volatile unsigned char *CHCONFIG0 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0000);
volatile unsigned char *CHCONFIG1 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0001);
volatile unsigned char *CHCONFIG2 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0002);
volatile unsigned char *CHCONFIG3 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0003);
volatile unsigned char *CHCONFIG4 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0004);
volatile unsigned char *CHCONFIG5 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0005);
volatile unsigned char *CHCONFIG6 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0006);
volatile unsigned char *CHCONFIG7 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0007);
volatile unsigned char *CHCONFIG8 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0008);
volatile unsigned char *CHCONFIG9 = (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x0009);
volatile unsigned char *CHCONFIG10= (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x000A);
volatile unsigned char *CHCONFIG11= (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x000B);
volatile unsigned char *CHCONFIG12= (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x000C);
volatile unsigned char *CHCONFIG13= (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x000D);
volatile unsigned char *CHCONFIG14= (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x000E);
volatile unsigned char *CHCONFIG15= (volatile unsigned char *) (DMAMUX_BASE_ADDR+0x000F);
In File main.c:
#include "registers.h"
:
:
*CHCONFIG2 = 0x00;
*CHCONFIG2 = 0x85;
Disabling a source
A particular DMA source may be disabled by not writing the corresponding source value
into any of the CHCFG registers. Additionally, some module-specific configuration may
be necessary. See the appropriate section for more details.
To switch the source of a DMA channel:
Initialization/application information
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
390
Preliminary
Freescale Semiconductor, Inc.
General Business Information