topic Re: DMA priority backwards? in LPC Microcontrollers

DMA priority backwards?

antonypace — Wed, 08 Nov 2017 15:07:59 GMT

On a LPC4078 I'm using 2 channels of DMA to send and receive through a SPI connection (SSP peripheral) and have send on channel 0 and receive on channel 1. I start the DMA on channel 0 first. Channel 0 has higher priority than channel 1. Both send and receive are 14 bytes of data.

I get channel 1 DMA complete interrupt first and I was xpecting to get channel 0 complete interrupt first.

It appears as though the send happens first and then the receive ie they are half duplex, which I am quite happy about.

Ant

Re: DMA priority backwards?

jeremyzhou — Fri, 10 Nov 2017 01:49:29 GMT

Hi Antony Pace,

Thank you for your interest in NXP Semiconductor products and

for the opportunity to serve you.

To provide the fastest possible support, I've attached the demo and please refer to it for details.

Have a great day,
TIC

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Re: DMA priority backwards?

antonypace — Fri, 10 Nov 2017 09:51:07 GMT

Hi,

Thank you for the reply. I've had a lookk at the demo code but I don't

see that it answers the question. Am I missing something?

Thanks

Ant

Re: DMA priority backwards?

jeremyzhou — Mon, 13 Nov 2017 06:11:17 GMT

Hi Antony Pace,

Thanks for your reply.

The demo is used to demonstrate the SPI working with the DMA which just meets your requirement.

Have a great day,
TIC