PXS20RM Datasheet, PDF (394/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

eDMA Channel Mux (DMA_MUX)
2. Clear the ENBL and 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 CHCONFIG
register, ensuring that the ENBL is set and the TRIG bit is cleared
Example 18-2. Configure source #5 Transmit for use with DMA Channel 2, with no periodic triggering
capability.
1. Write 0x00 to CHCONFIG2 (Base Address + 0x02)
2. Configure Channel 2 in the DMA, including enabling the channel
3. Write 0x85 to CHCONFIG2 (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
CHCONFIG registers. Additionally, some module specific configuration may be necessary. Please refer
to the appropriate section for more details.
Switching the source of a DMA Channel
1. Disable the DMA channel in the DMA and re-configure the channel for the new source
2. Clear the ENBL and TRIG bits of the DMA channel
18-10
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor