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dvvrao

Simulator, UART with DMA, PIC32, MPLAB X IDE

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dvvrao    0

dvvrao
Posted

Does the simulator for PIC32MX470F512L support UART with DMA operation? 
I wrote a program that transmits a character using UART with DMA, but does not work. 
I used Dynamic USART driver with Buffer Que Data Transfer model using DMA.

PFA the package file of the project.

Please let me know if there is any thing wrong with the code or harmony configuration.

usart_loopback.zip

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Orunmila    49

Orunmila
Posted

Please feel free to upload code, pictures, videos, whatever you need to make it clear over here, that is the reason we made this forum, to overcome exactly that problem, so thank you for doing that!

George writes the simulator, so there is no better person to help you!

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Orunmila    49

Orunmila
Posted

Quick look I see that DMA is supported and so is UART, so I would expect that this would be covered. Will get some time on the weekend to try this out and will let you know if I find something interesting.

I am sure there are others on here who have more experience at this and can just throw up an answer though 🙂

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dvvrao    0

dvvrao
Posted

I had to create this post here to upload my code and mention the link on that forum.

There i could not upload the code as it was exceeding the 500KB limit.

When i get a solution for my problem in that forum i will update here.

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ric    11

ric
Posted

Of course, the simulator may be fine. It may just be Harmony that's not implementing USART via DMA correctly...

 

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Orunmila    49

Orunmila
Posted

Follow up: From George's response on the Microchip Forum this was verified as a bug in the simulator DMA implementation. 

He also posted that this "should" be fixed in MPLAB X 5.20, which means it may end up only being included in 5.25

Response on the forum was this:

 
Quote

 

Re: Simulator, UART with DMA, PIC32, MPLAB X IDE 3 days ago (permalink)
Thanks, that was the missing piece of information that I needed.  I am now convinced the simulator is "broken".  I will write a trouble report to get this fixed.  Unfortunately I would guess this gets fixed in 5.25 not 5.20 😞 More unfortunately, I do not think there is a workaround that can be used for the current version of MPLAB X that you are using.

For those of you who enjoy observing the sausage being made (you know who you are...):  The simulator's DMA peripheral is writing directly to memory instead of to the SFR wrapper objects the simulator uses emulate SFRs.  The simulator's UART is faithfully observing (ala gang of four Observer pattern) the TXREG SFR for notification of a new value being written.  Unfortunately that notification never comes because the DMA did an end-run around the SFR by writing directly to memory.  

This all works perfectly when you use the DMA in the other direction, ie receive a bunch of characters and copy them to a memory buffer.

 

 

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