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Can PIT trigger DMA?

Question asked by Paul Swanson on Jul 24, 2019
Latest reply on Jul 29, 2019 by Mark Butcher

Hello,

 

I'm a little confused about how PIT events and DMA relate, on the FRDM-KL25

 

What I'm looking to achieve is this ...

 

Ideally, on the expiration of a PIT timer I want to asynchronously do two things:

  • Transfer a single value from a given memory location to a given register
  • Transfer a fixed array of two byte values through to DAC (play a tiny 12bit audio sample)

 

However, I'm not completely sure if this is possible.

 

Firstly, reading the application note "Application of Asynchronous DMA operation" (for the KL25), it lists in section 3.2 the modules that are capable of generating DMA requests, PIT is not among them.

 

Secondly, referring to pages 87-8 of the "KL25 Sub Family Reference Manual" it specifies that "... PIT generates periodic trigger events to the DMA channel mux ...".

 

So, can I or can't I use PIT events to initiate a DMA transfer?

 

I'm working mostly just with CMSIS and occasionally some Freescale libraries on this project.

 

Any help greatly appreciated!

 

Paul Swanson#

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