topic Re: DMA to GPIO in Kinetis Microcontrollers

DMA to GPIO

swa14720 — Tue, 23 Apr 2019 18:33:27 GMT

Hi,

I am using Kinetis MK22 MCU. I want to transfer data from memory to GPIO PortC using DMA. When I gave TCD0_DADDR = address of GPIOC_PSOR, the DMA is not working as expected (i.e the data is not been transferred to DADDR). Does MK22 DMA support GPIO registers as destination address?

Re: DMA to GPIO

mjbcswitzerland — Tue, 23 Apr 2019 18:54:12 GMT

There is no restriction to doing DMA transfers to GPIO on the K22.

In the uTasker project a reference application is to bridge a UART input to GPIO output (almost as if it were a wired connection) by using this configuration:

        // Configure the DMA trigger from the UART input pin change to toggle an alternative port so that the input signal is mirrored to that output without CPU intervention
        //
        static const unsigned long ulOutput = PORTC_BIT16;               // the output to be mirrored to
        fnConfigDMA_buffer(9, DMAMUX0_CHCFG_SOURCE_PORTB, sizeof(ulOutput), (void *)&ulOutput, (void *)&(((GPIO_REGS *)GPIOC_ADD)->PTOR), (DMA_FIXED_ADDRESSES | DMA_LONG_WORDS), 0, 0); // use DMA channel 9 without any interrupts (free-runnning)

Note that it uses the PTOR register so that every write causes a toggle. Maybe you are not using suitable register or the value being written to it is not correct (?)

Regards

Mark

Complete Kinetis solutions for professionals, training and support: http://www.utasker.com/kinetis.html
Kinetis K22:
- http://www.utasker.com/kinetis/FRDM-K22F.html
- http://www.utasker.com/kinetis/TWR-K22F120M.html
- http://www.utasker.com/kinetis/BLAZE_K22.html
- http://www.utasker.com/kinetis/tinyK22.html

Re: DMA to GPIO

Robin_Shen — Tue, 30 Apr 2019 08:23:37 GMT

Please refer the AN4419 Using DMA and GPIO to emulate timer functionality on Kinetis Family devices
I think you'd better use GPIOx_PDOR instead of use GPIOx_PSOR.

Best Regards,

Robin

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Re: DMA to GPIO

swa14720 — Wed, 01 May 2019 19:17:51 GMT

Thanks @robin_shen

Thanks for your help. I figured this out and exactly that was the issue.i was trying to write onto psor and read from it. But psor doesn't support read. When I changed Daddr to read from pdor it worked perfectly.