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This version (27 Sep 2022 16:30) was approved by Darius B.The Previously approved version (27 Sep 2022 10:35) is available.Diff

Table of Contents

No-OS Interrupts API

Description

The IRQ framework provides a way to handle peripheral (external) interrupts when using the No-OS platform drivers.

Interface Documentation

The IRQ interface documentation is generated using the Doxygen tool and it is available at:

Initialization example

There are 2 types of IRQ descriptors:

  • A GPIO interrupt controller descriptor, that handles interrupt configurations on individual GPIO pins.
  • A global interrupt controller, that handles all the other interrupt sources.

Global interrupt controller initialization

int ret;
 
struct no_os_irq_ctrl_desc *global_desc;
struct no_os_irq_ctrl_init_param global_desc_param = {
        .irq_ctrl_id = 0,
        /** Global IRQ controller specific ops. This struct is platform dependent. */
        .platform_ops = &max_irq_ops,
        .extra = NULL
};
 
ret = no_os_irq_ctrl_init(&global_desc, &global_desc_param);
if (ret)
        return ret;

The irq_ctrl_id and extra fields are not used by any of the IRQ API functions, so they can be given arbitrary values that may be useful to application code.

GPIO interrupt controller initialization

int ret;

struct no_os_irq_ctrl_desc *gpio_irq_desc;
struct no_os_irq_ctrl_init_param gpio_irq_desc_param = {
        /** GPIO port number */
        .irq_ctrl_id = 0,
        /** GPIO IRQ controller specific ops. This struct is platform dependent. * /
        .platform_ops = &max_gpio_irq_ops,
        .extra = NULL
};

ret = no_os_irq_ctrl_init(&gpio_irq_desc, &gpio_irq_desc_param);
if (ret)
        return ret;

The extra field is not used by any of the IRQ API functions (it's simply stored in gpio_irq_desc's extra field), so it can be given arbitrary values that may be useful to application code.

Usage examples

Global interrupt controller

This example shows how to register callbacks and enable/disable global interrupts. This assumes that the global interrupt controller descriptor has been initialized. As for the moment, all the interrupts have the same (0) priority level. 

void uart_callback_fn(void *context)
{
        // interrupt code
}
int ret;
 
struct no_os_callback_desc uart_cb = {
        /** Callback to be called when the event an event occurs. */
        .callback = uart_callback_fn,
        /** Parameter to be passed when the callback is called */
        .ctx = NULL,
        /** Event that triggers the calling of the callback. */
        .event = NO_OS_EVT_UART_RX_COMPLETE,
        /** Interrupt source peripheral specifier. */
        .peripheral = NO_OS_UART_IRQ,
        /** Platform specific HAL descriptor. This may be used to uniquely identify a registered callback */
        .handle = MXC_UART0
};
 
/** 
 * Register a new callback for an event/peripheral pair (in case there is already one registered, it will be overwritten).
 * In the case of the global interrupt controller, the irq_id refers to the interrupt vector entry number 
 * of the peripheral (this should be unique).
*/
ret = no_os_irq_register_callback(global_desc, UART0_IRQn, &uart_cb);
if (ret)
        return ret;
 
/**
* Set the priority level of an interrupt.
*/
ret = no_os_irq_set_priority(global_desc, UART0_IRQn, 1);
if (ret)
        return ret;
/** 
 * Enable the handling of interrupts from a peripheral specified by **irq_id**.
 * Without this step, the interrupt routine won't be called.
*/
ret = no_os_irq_enable(global_desc, UART0_IRQn);
if (ret)
        return ret;
 
/** 
 * The callback will now be triggered once a RX complete event occurs on UART0.
*/
 
/** 
 * Registering a callback for a GPIO peripheral from the global interrupt controller will result in an error.
*/
ret = no_os_irq_register_callback(global_desc, GPIO0_IRQn, &uart_cb);
 
/**
 * Unregistering a callback is done in this way. 
*/
ret = no_os_irq_unregister_callback(global_desc, UART0_IRQn, &uart_cb);
if (ret)
        return ret;
 
/**
 * The calllback will no longer be triggered.
*/

GPIO interrupt controller

The following example shows how to handle GPIO interrupts. This assumes that both a global interrupt controller and a GPIO interrupt controller have been initialized. 

void gpio_callback_fn(void *ctx)
{
        // interrupt code
}
int ret;
 
struct no_os_callback_desc gpio_cb = {
        /** Callback to be called when the event an event occurs. */
        .callback = gpio_callback_fn,
        /** Parameter to be passed when the callback is called */
        .ctx = NULL,
        /** Event that triggers the calling of the callback. */
        .event = NO_OS_EVT_GPIO,
        /** Interrupt source peripheral specifier. */
        .peripheral = NO_OS_GPIO_IRQ,
        /** Not used in the case of a GPIO IRQ controller */
        .handle = NULL
};
 
/**
 * In the context of using the GPIO interrupt controller specific platform ops, the irq_id refers to the pin number.
 * The callback will be registered on pin 5 of the GPIO port 0 (the port is specified by the id field of the 
 * gpio_irq_desc).
*/
ret = no_os_register_callback(gpio_irq_desc, 5, &gpio_cb);
if (ret)
        return ret;
 
/**
 * Set the trigger condition of the interrupt on pin 5 to rising edge.
*/
ret = no_os_trigger_level_set(gpio_irq_desc, 5, NO_OS_IRQ_EDGE_RISING);
if (ret)
        return ret;
 
/**
* This calls the interrupt priority set function of the parent controller.
*/
ret = no_os_irq_set_priority(gpio_irq_desc, 5, 1);
if (ret)
        return ret;
 
/**
 * Enable interrupts on pin 5.
*/
ret = no_os_irq_enable(gpio_irq_desc, 5);
if (ret)
        return ret;
 
ret = no_os_irq_enable(global_desc, GPIO0_IRQn);
if (ret)
        return ret;
 
/**
 * The callbacks on pin 5 (GPIO 0) now get triggered on rising edge.
/*

Platform specific fields

The handle field of the no_os_callback_desc struct is platform specific and has the following values:

  • STM32: In the case that a global interrupt controller is used, the handle is a HandleTypeDef struct. For a GPIO controller, it's ignored.
  • Maxim: In the case that a global interrupt controller is used, the handle is a reference to a struct containing the peripheral's register state. These should be found in the Maxim's SDK (e.g MXC_TMR_GET_TMR(0) or MXC_TMR0. The naming for other peripherals is similar.). For a GPIO IRQ controller, this field can be ignored.
  • RPi Pico: In the case that a global interrupt controller is used, the handle is a struct containing peripheral register state (e.g uart0). For a GPIO IRQ controller, it's ignored.

Other platforms do not need to have the handle field set, as it's ignored.

resources/no-os/drivers/interrupt.txt · Last modified: 27 Sep 2022 16:30 by Darius B

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