LPC865 DMA channels for different output compare match from one FTM

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LPC865 DMA channels for different output compare match from one FTM

425件の閲覧回数
shoichi_kojima
Contributor I

Dear fellows,

I'm trying employ plural DMA channels for several compare/match in one FTM.

I've been using other LPC8xx MCUs sych as LPC824, LPC845 etc to do the same ways using SCTimers.

As SCTimer provides very flexible event generation with logical-OR conditions even to trigger DMA channels. e.g. OR-ed request triggering from different plural comparators in SCTimer.

I can NOT find the ways to do those on LPC865 DMAC and INMUX arcitecture.

Does anyone have good suggestions ?

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shoichi_kojima
Contributor I

Thank you for your information about FTM samples.

But, I gradually remember that "FlexTimer" IP has been designed and implemented in Freescale-brand products...

If so, I'm taking a wrong choice to my application. I'd given-up to do that on Kinetis serise etc...

Anyway, let me try to explain my request in detail and simple to find a solution.

I want to generate one PWM cyclinc pulse output signal in constant rate and duty.

But, internally I would like to invoke/trig DMA just once-per-twice (or once-per-three-PWM cycles).

It's a "Thin-out" kind of logic reducing the occuerence of DMA keeping synchronization to PWM output.

 

In case of SCTimer I can set the period for three PWM cycle long and with three-pairs of comparators to drive one common output node from SCTimer with each comparator pair setting representing the first, second and third flip timings, while DMA request trigger is set enabled just on one of those six comparison event.

FlexTimer does NOT have flexibility to take those scenario by itself, I suppose.

If the event-acceptor pathways, in this case connection to DMAC, have some thin-out feature/programmable-behavior, that would also be a solution to me.

 

SCTimer's nature seems to be a generic State-Controlled event-generatior equally treating MCU internal event such as triggering DMA and output flipflop behind physical output PINs. Not so much to with 'timer' behavior commonly imaginable.In fact, I'd often utillize SCTimer for detecting I2C's Start-Condition and Stop-Condition that indicates Bus-busy signal.

Thanx

 

 

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Alice_Yang
NXP TechSupport
NXP TechSupport

Hello @shoichi_kojima 

Thanks for your sharing. I talked with our internal team member and SE team. Sorry so far we haven't a solution  with LPC865. Sorry for the inconvenient to you.

 

BR

Alice

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Alice_Yang
NXP TechSupport
NXP TechSupport

Hello @shoichi_kojima 

Yes, FTM is not flexible as SCT. 

You can describe your required function more detail, I'll help see if FTM can achievable.

Also there are some FTM demos under SDK, you can refer to:

Alice_Yang_0-1709794205184.png

 

BR

Alice

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