DMAMUX configuration example for periodic triggering

[CoolMo]

Hi all,

I seem not to be able to achieve periodic DMA transfers using DMAMux periodic triggering functionality.

I read on SPC574Kx reference manual that (§7.3.9.2)

• DMAMUX1 receives PIT_0 Trigger 0-4
• DMAMUX2 receives PIT_0 Trigger 5

and that (Table44):

• PIT_0 periodic trigger 1 is mapped to DMA channel 9

Now, suppose I have configured PIT_0 channel 1 to be my periodic source, I should then set my eDMA transfer control descriptor data in DMA_0.TCD[9]

my DMACHMUX config is:

DMACHMUX_1.CHCONFIG[1].B.ENBL = FALSE; //§ 25.3.1

DMACHMUX_1.CHCONFIG[1].B.SOURCE = 0;

DMACHMUX_1.CHCONFIG[1].B.TRIG = TRUE;

DMACHMUX_1.CHCONFIG[1].B.ENBL = TRUE;

Am I correct?

Unfortunately I cannot get the dma channel service to start upon PIT timer expiration.

What am I missing?

Is there a configuration example available somewhere?

Thanks in advance,

M

[CoolMo]

my fault:

DMACHMUX_1.CHCONFIG[1].B.SOURCE = 59U;

// just use an "ALWAYS ON" source on the specific DMAMUX.... (see §7.3.9.3 Table43)

// the always on source serves as a gating signal and to allow

// trigger pulses form PIT_0.Ch1 start the eDMA channel

😉

[Giuseppe DI-GIORE · Accepted solution]

Hello,

your analysis is correct:

• Use Always-On as source
• Configure the PIT and the specific channel as trigger
• Set the trigger bit in DMAMUX configuration

In the coming update (beginning of February) of SPC5Studio (link) there will be a specific demo about DMA triggering configuration and usage.

The name of the demo is:

• SPC584Bxx_RLA PIT triggers DMA Test Application for Discovery

Attached the main.c for this demo.

Regards,

Giuseppe