topic Re: How to use CTIMER DMA correctly on LPC546x? in LPC Microcontrollers

How to use CTIMER DMA correctly on LPC546x?

geweilin — Mon, 16 Mar 2020 09:23:37 GMT

I am now using CTimer to output a specific digital wave signal on LPC54618, and DMA is used.
A timing parameter table TimeParmTab[]={A,B,C,D} is defined to be copy to Match Register.
The transfer type is configured as MemoryToMemory, it works ok when CTimer interrupt is enabled,
and CTimer interrupt register flags be cleared in the ISR routine.
But when I disable the CTimer interrupt and don't clear interrupt register flags, the DMA could only be triggered once,
and can not continue.
The DMA also can not work when configured as PeripheralToMemory.

So, I have two question:
1. Whether the CTimer DMA can work continously without software process(clear CTimer interrupt flags)?
if yes, then how is the correct method?
2. Whether the CTimer DMA can work when configured as PeripheralToMemory?
if yes, then how is the correct method?

Thank you!

Re: How to use CTIMER DMA correctly on LPC546x?

Sabina_Bruce — Thu, 19 Mar 2020 19:13:09 GMT

Hello ,

Hope you are doing well.

1.No, the interrupt needs to be cleared if not the DMA request will not be cleared. Please review section 17.6.1 of the reference manual.

2. Could you please rephrase your question. I am not sure if I am understanding you correctly. Would you like the match event to trigger a dma transfer from a peripheral to memory such as UART, for example. Or would you like to save information from the CTIMER?

Best Regards,

Sabina

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