topic Re: How to Increase the size of transfer buffer using DMA for UART? in Kinetis Microcontrollers

How to Increase the size of transfer buffer using DMA for UART?

Amit_Kumar1 — Wed, 14 May 2014 07:45:04 GMT

Using the below PE settings I am able to transfer 8 bytes of data but my buffer contains 15 bytes of data. So whats the process of transferring all the data present in the buffer? I have used DMAT_Ldd component from PE. I am using FRDM-K20D50M board with codewarrior 10.5.

Kind Regards

Amit Kumar

Re: How to Increase the size of transfer buffer using DMA for UART?

jeremyzhou — Thu, 22 May 2014 06:51:06 GMT

Hi Amit,

I didn't figure out the problem after I had a brief look through the screenshot you provided,

So I'm wondering if you could upload your project to the community.

I'm looking forward to your reply.
Have a great day,
Ping

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Re: Re: How to Increase the size of transfer buffer using DMA for UART?

Amit_Kumar1 — Fri, 23 May 2014 05:41:39 GMT

Hi jeremyzhou

Thanks for the concern. Please find the attachment. The issue is when executing this program, the o/p i am getting is "hello wo" which is only 8 char, but my buffer size is 16 char. Following is the o/p.

Thanks & Regards

Amit Kumar

Re: How to Increase the size of transfer buffer using DMA for UART?

jeremyzhou — Mon, 26 May 2014 07:03:10 GMT

Hi Amit,

Thanks for your reply.

I will test this project with FRDM-K20D50 and inform you immediately if I figure out this problem.

Have a nice day!

Ping

Re: How to Increase the size of transfer buffer using DMA for UART?

jeremyzhou — Mon, 26 May 2014 07:57:59 GMT

Hi Amit,

I think I've found the reason of why only 8 bytes have been transfered.

From your project, you set the [Transfer control]: Single transfer, when triger source:UART transmit exist, then DMA will transfer all 16 bytes to UART data register immediately.

However the UART0 have only 8-entry transmint FIFO which mean it can store 8 bytes and the FIFO will bypass other bytes.

Final, we've just received 8 byte from UART0.

Wish my support help.

Have a great day,
Ping

Re: How to Increase the size of transfer buffer using DMA for UART?

Amit_Kumar1 — Fri, 30 May 2014 12:51:12 GMT

HI Jeremyzhou

Thanks for the response, SO according to u if I change the transfer from single transfer to nested transfer it should work? I will test this and will update it soon.

Regards

Amit Kumar

Re: How to Increase the size of transfer buffer using DMA for UART?

marek_neuzil — Fri, 22 Aug 2014 06:37:17 GMT

Hello Amit,

You are using DMATransfer_LDD component that has been replaced by the new DMAChannel_LDD (already available in the CW MCU 10.5). See the thread https://community.freescale.com/thread/328100 (response from Marek Varecha).

Best Regards,

Marek Neuzil