Help with using mp_sched_scheduler

[Kyderio]

Hi, I am new to micropython and trying to port GPIO IRQ feature for ameba boards. This is my python script.

import machine

def button_interrupt(pin):
    if pin.value() == 0:  # Button is pressed (assuming the pull-up configuration)
        print("Button pressed")
    else:
        print("Button released")

button_pin = machine.Pin("PA_12", machine.Pin.IN, machine.Pin.PULL_UP)

button_pin.irq(handler=button_interrupt,trigger=machine.Pin.IRQ_RISING)

This is my objpin.c code where

void gpio_demo_irq_handler(uint32_t id, gpio_irq_event event)
{
    // TODO: pass real user-defined handler
    printf("This is a demo irq handler");
}

STATIC mp_obj_t machine_pin_irq(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args)
{
    enum
    {
        ARG_handler,
        ARG_trigger,
        ARG_hard
    };
    static const mp_arg_t allowed_args[] = {
        {MP_QSTR_handler, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE}},
        {MP_QSTR_trigger, MP_ARG_INT, {.u_int = IRQ_FALL | IRQ_RISE}},
        {MP_QSTR_hard, MP_ARG_BOOL, {.u_bool = false}},
    };

    // deinit the GPIO first
    pin_obj_t *self_in = MP_OBJ_TO_PTR(pos_args[0]);
    gpio_deinit((gpio_t *)&(self_in->obj));

    printf("This is a test for irq function\n");

    pin_irq_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);

    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    if (n_args > 1 || kw_args->used != 0)
    {
        // Configure IRQ.

        self->trigger = args[ARG_trigger].u_int;
        self->id = self_in->id;

        gpio_irq_init((gpio_irq_t *)&(self->obj), self->id, gpio_demo_irq_handler, 0); // set handler
        gpio_irq_set((gpio_irq_t *)&(self->obj), self->trigger, true);                 // Set Trigger mode
        gpio_irq_enable((gpio_irq_t *)&(self->obj));
    }

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pin_irq_obj, 1, machine_pin_irq);

I have read up a bit, but im not sure how to use mp_sched_schedule to pass the user-defined handler into the c code

void gpio_demo_irq_handler(uint32_t id, gpio_irq_event event)
{
    // TODO: pass real user-defined handler
    printf("This is a demo irq handler");
}

Can someone guide me towards the right direction? Thanks!

[jimmo]

You need to have some structure in RAM that can map the information you receive in the C IRQ handler (i.e. id) to the handler that was passed to the pin.irq function. On some ports this is done by having the handler be a member of the pin struct (but this means you have to make the pin struct non-const and therefore in bss not rom), on other ports there's just a table in memory.

Note that these handlers have to be "root pointers" (so the GC doesn't clean them up).

Look at e.g. stm32/extint.c for example (it uses MP_REGISTER_ROOT_POINTER to create a table of handlers).

But also worth looking at shared/runtime/mpirq.c which is supposed to be a common helper for implementing the .irq method correctly (this is supposed to return an irq object that can be used to retrieve the event flags etc). Not all ports use this (yet).

[jimmo]

Also mpirq.c handles the hard/soft and how to invoke the callback directly or via the scheduler.

[Kyderio]

Thanks so much for the fast response! Let me give it a try :)