Follow-up question to DMA #18047
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Hello everyone After my last question about DMA I have a follow-up question. When SM and DMA are collecting data, I use "normal" Micropython to do stuff with the data. In this while-loop, I also check, if SM is still active Now and then I loose the input signals for a short or longer periode. If that happens, the checks I do start a second loop, where it's checking a few more times with a delay between each check, if maybe the signal is back. If not, SM and DMA are closed, reset and started again. Now my problem: When simulating this, by switching of the device, that delivers the signal, everything is ok and the checks are done, but when I switch it back on, the code is still not able to detect the signal. If a do a hard-reset, everything works again. What I did so far (tried in different orders): After also trying different code it seems, that there is still something in the DMA-settings, that doesn't get cleared and stays on. My question: Greetings |
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Replies: 2 comments 5 replies
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really wants some brackets: |
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Yes of course. It was a list indicating what had already been tried, but without regard to correct syntax. |
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It's important to shut everything down, otherwise the RP2 can be left in an unstable state. My approach is to run the application in a obj = MyObject() # A class using SM and DMA instances
try:
asyncio.run(application()) # Code that uses obj
finally:
obj.deinit() # Shut downThe def deinit(self):
self._dma.active(0)
self._dma.close()
self._csn.irq(None) # Disable intarrupt
self._sm.active(0) # Stop the SM |
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Hello Peter I have now also switched to this solution. I had hoped that I would not have to restart the RP2350, but obviously DMA is not capable of being restarted in a stable state, and I can't see why?! I see that as soon as the signal is present again, the state machine resets and starts again and fills the RX_FIFO and then stalls because DMA does not retrieve the data. All attempts to restart and reconfigure DMA have failed. Now the RP2350 simply restarts. I have added a loop, that stops SM and DMA when the signal is lost and then waits for Pin0.values = 1 (which indicates that the signal is back again) when the signal is lost, so the RP2350 is not restarted in a endlees loop waiting for a signal. After that, machine.reset() is executed, the programme is restarted, and everything continues to run smoothly. Thank you very much vor your input! Greetings |
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That doesn't make any sense. 0x4002_0000 is |
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According to the RP2350 datasheet:
Datasheet RP2040: If I haven't overlooked anything, your statement is correct with regard to RP2040, but I am working with the RP2350. |
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Jack, you are indeed correct. However, doing a lot of work using multiple DMA channels, I have yet to find a single occurrence where the stuff hangs beyond all hope. Usually a proper cleanup sequence and de-initialisation does the trick. It's also quite a while ago that I had to reset the DMA subsystem at all. |
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It's important to shut everything down, otherwise the RP2 can be left in an unstable state. My approach is to run the application in a
try...finallybock, ensuring that any exit will shut down cleanly:The
deinitmethod looks like this