How to determine PIO instance assigned to a SerialPIO ?

[myklemykle]

Hi,

Is there any handy way to query which PIO resources are being used by a given SerialPIO instance?

One gotcha I've had since upgrading to 4.0.2 is that the algorithm that assigns PIO resources to a SerialPIO instance now allocates state machines from PIO1 first, whereas before it used PIO0 first. My code was glossing over that difference, but it was important to know for a couple of reasons. For one, I switched the tip & ring pins of my device between several different peripherals, like so:

void configOutputs(){
  switch(config.portMode.get()) {
    case MODE_MIDI:
      gpio_set_function(PIN_TIP, GPIO_FUNC_PIO0); // SerialPIO SSerialTip1
      gpio_set_function(PIN_RING, GPIO_FUNC_PIO0); // SerialPIO SSerialRing1 (inverted TX)
      break;
    case MODE_SYNC:
      gpio_set_function(PIN_TIP, GPIO_FUNC_SIO);
      gpio_set_function(PIN_RING, GPIO_FUNC_SIO);
      break;
    case MODE_AUDIO:
      gpio_set_function(PIN_TIP, GPIO_FUNC_PWM);
      gpio_set_function(PIN_RING, GPIO_FUNC_PWM);
  }
} 

The MIDI portion of that stopped working in core 4.0.2, because the SerialPIO instances that provide the MIDI mode are not ending up on PIO0 any more; they're now appearing on PIO1. So I had to tweak that function a little:

void configOutputs(){
  switch(config.portMode.get()) {
    case MODE_MIDI:
      gpio_set_function(PIN_TIP, GPIO_FUNC_PIO1);
      gpio_set_function(PIN_RING, GPIO_FUNC_PIO1);
      // we have to re-enable the pin inversion when we switch modes now:
      gpio_set_outover(PIN_RING, 1);
      break;
    case MODE_SYNC:
      gpio_set_function(PIN_TIP, GPIO_FUNC_SIO);
      gpio_set_function(PIN_RING, GPIO_FUNC_SIO);
      break;
    case MODE_AUDIO:
      gpio_set_function(PIN_TIP, GPIO_FUNC_PWM);
      gpio_set_function(PIN_RING, GPIO_FUNC_PWM);
  }
} 

This works for me, for now, but OTOH if I add some other PIO-using library to this sketch, I won't be able to predict which PIO instance goes to which SerialPIO instance.

-m-