MicroPython Forum (Archive)

@rgcoldeman, thank you very much to point me to you project, which shows how to use DMA! What I don't understand: How do you know, that these channels are not used by anything? ( I had no knowledge of mem32[], so easy.) Yes, I think, DMA should be able to be clocked at a certain clock rate too and ...

Nice work! I've done a DDS generator with a completely different approach, it may be some of the techniques can be combined; it is documented on https://www.instructables.com/Arbitrary-Wave-Generator-With-the-Raspberry-Pi-Pic/ (also a thread here: https://forum.micropython.org/viewtopic.php?f=21&t=9...

Very nice, thanks for sharing!

Indeed mem32 is slow. I used viper to get the address of the array to pass on to the registers, not for speed, since it's only for configuration. In another test I compared blink speed between mem32 and ptr (both viper). ptr could get me up to 15.625MHz, (4 clock cycles per loop), mem32 well below 1...

Thanks, it looks very neat!

I've posted a more detailed description of the project on https://www.instructables.com/Arbitrary ... ry-Pi-Pic/

Ah, you refer to the DMA classes posted by mw66 on this list? It looks awesome and I hope those classes or similar will eventually be included with the RP2 micropython. (actually I don't find the implemation of 'SetChannelData' method used in the examples) The code I posted directly writes the DMA r...

The code is complete. It should work out of the box. I used the original 1.13 RP2 micropython version. Where would you expect a 'SetChannelData' method/function?

OK it works, it is amazing: true 125Msps AWG without even overclocking, and without CPU!! Trick was to use a second DMA channel to reconfigure with a single write to the READ register the first. The DMA sends 32-bit words but the PIO only consumes 8 bits a time, so there is no delay in the reconfigu...

Just not easy for a newbie trying to stick to micropython... FWIW, you can control the PIO from MicroPython. See https://github.com/micropython/micropython/blob/master/examples/rp2/pio_ws2812.py for an example that uses data from memory to control a pin. Thanks! yes it's very powerful. Anyway the p...

Yes, from what I read in the datasheet it should be possible to do DMA->PIO->GPIO. That's probably the best solution, it gives some extra flexibility on frequency from the PIO clock divider and on the choice of pins. Just not easy for a newbie trying to stick to micropython...