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Get DMA count

Question asked by fraccaroli.francesco on May 29, 2017
Latest reply on Jun 5, 2017 by hersey.stephen.001

Hi all,

I'm using USART with DMA to implement a Modbus rtu slave node.

I want to implement this:

- the USART use DMA to store received characters in a buffer

- a contdown-timer count the time between character to recognise the end of the frame.

- the timer is loaded when new characters are loaded by the DMA. I want to recognize them with a 20kHz ISR that I use to do other stuff: Checking the value of the DMA count I know if new bytes has arrived.

I use the DMA as a sort of FIFO, because:

- I don't know the size of the message

- I don't want to use a ISR for each character to avoid loss of information.

 

Unfortunately, I didn't find any information about getting DMA count!

Does anyone can help me?

Thank you very much.

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