Thanks for the insights. I've only written one PIO program, and it's for a DHT22 sensor. I divided the clock down to 1 MHz so I could count microseconds. Really

Thanks for the insights. I've only written one PIO program, and it's for a DHT22 sensor. I divided the clock down to 1 MHz so I could count microseconds. Really, CPU bit-banging would have worked fine at those speeds. Now that I think about it more, you're right. Best case scenario for reading a bit would be to wait for the pin to go high/low, then push the corresponding bit into the input shift register, and have that automatically flush to DMA every 32 bits, say. Can't do better than some fraction of the clock speed because of the multiple instructions needed.