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Given that RP2040 needs external flash, I'm quite worried about the performance when pulling uncached code from it (on top of using M0 core - I'm used to M4 by now). I know the MCU has 16kB of cache, but my firmware for which I'm still deciding on whether to port it to RP2040 or not is about 80k. Does anyone here has some real-life data on this?

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With 80k of firmware, you can just put it all in RAM ;)

The M0 is not much slower than M4 when running at the same clock, and the RP2040 can run quite fast. Of course it's different if you comparing to M4F and need float32.

If you end up putting code in SPI flash and you need predictable latency, you will need to put ISRs and everything they depend on in RAM [0]. However, if you don't need down-to-microsecond latency, then it's just fine.

[0] eg https://github.com/lancaster-university/codal-rp2040/blob/ma...

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