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The NEC IR transmission protocol uses pulse distance encoding of the message bits. Each pulse burst is 562.5μs in length, at a carrier frequency of 38kHz (26.3μs). Logical bits are transmitted as follows:

Logical '0' – a 562.5μs pulse burst followed by a 562.5μs space, with a total transmit time of 1.125ms;

Logical '1' – a 562.5μs pulse burst followed by a 1.6875ms space, with a total transmit time of 2.25ms.

When a key is pressed on the remote controller, the message transmitted consists of the following in order:

1. A 9ms leading pulse burst (16 times the pulse burst length used for a logical data bit).
2. A 4.5ms space.
3. The 8-bit address for the receiving device.
4. The 8-bit logical inverse of the address.
5. The 8-bit command.
6. The 8-bit logical inverse of the command.
7. A final 562.5μs pulse burst to signify the end of message transmission.

LibDriver IR_REMOTE is the full function driver of ir_remote launched by LibDriver. It provides NEC IR remote decoding function. LibDriver is MISRA compliant.

• Instruction
• Install
• Usage
  • example basic
• Document
• Contributing
• License
• Contact Us

/src includes LibDriver IR_REMOTE source files.

/interface includes LibDriver IR_REMOTE GPIO platform independent template.

/test includes LibDriver IR_REMOTE driver test code and this code can test the chip necessary function simply.

/example includes LibDriver IR_REMOTE sample code.

/doc includes LibDriver IR_REMOTE offline document.

/datasheet includes IR_REMOTE datasheet.

/project includes the common Linux and MCU development board sample code. All projects use the shell script to debug the driver and the detail instruction can be found in each project's README.md.

/misra includes the LibDriver MISRA code scanning results.

Reference /interface GPIO platform independent template and finish your platform GPIO driver.

Add /src, /interface and /example to your project.

#include "driver_ir_remote_basic.h"

volatile uint8_t g_flag;                       
uint8_t (*g_gpio_irq)(void) = NULL;                      
uint8_t res;
uint32_t i;
uint16_t timeout;

static void a_receive_callback(ir_remote_t *data)
{
    switch (data->status)
    {
        case IR_REMOTE_STATUS_OK :
        {
            ir_remote_interface_debug_print("ir_remote: irq ok.\n");
            ir_remote_interface_debug_print("ir_remote: add is 0x%02X and cmd is 0x%02X.\n", data->address, data->command);
            g_flag = 1;
            
            break;
        }
        case IR_REMOTE_STATUS_REPEAT :
        {
            break;
        }
        case IR_REMOTE_STATUS_ADDR_ERR :
        {
            ir_remote_interface_debug_print("ir_remote: irq addr error.\n");
            
            break;
        }
        case IR_REMOTE_STATUS_CMD_ERR :
        {
            ir_remote_interface_debug_print("ir_remote: irq cmd error.\n");
            
            break;
        }
        case IR_REMOTE_STATUS_FRAME_INVALID :
        {
            ir_remote_interface_debug_print("ir_remote: irq frame invalid.\n");
            
            break;
        }
        default :
        {
            ir_remote_interface_debug_print("ir_remote: irq unknown status.\n");
            
            break;
        }
    }
}

...
    
/* gpio init */
res = gpio_interrupt_init();
if (res != 0)
{
    return 1;
}

/* set the irq */
g_gpio_irq = ir_remote_basic_irq_handler;

...
    
/* basic init */
res = ir_remote_basic_init(a_receive_callback);
if (res != 0)
{
    (void)gpio_interrupt_deinit();
    g_gpio_irq = NULL;
}

...
    
/* loop */
for (i = 0; i < times; i++)
{
    /* output */
    ir_remote_interface_debug_print("%d/%d.\n", i + 1, times);

    /* 5s timeout */
    timeout = 500;

    /* init 0 */
    g_flag = 0;

    /* check timeout */
    while (timeout != 0)
    {
        /* check the flag */
        if (g_flag != 0)
        {
            break;
        }

        /* timeout -- */
        timeout--;

        /* delay 10ms */
        ir_remote_interface_delay_ms(10);
    }

    /* check the timeout */
    if (timeout == 0)
    {
        /* receive timeout */
        ir_remote_interface_debug_print("ir_remote: receive timeout.\n");
        (void)ir_remote_basic_deinit();
        (void)gpio_interrupt_deinit();
        g_gpio_irq = NULL;

        return 1;
    }
    
    ....
}

...
    
/* basic deinit */
(void)ir_remote_basic_deinit();

/* gpio deinit */
(void)gpio_interrupt_deinit();
g_gpio_irq = NULL;

return 0;

Online documents: https://www.libdriver.com/docs/ir_remote/index.html.

Offline documents: /doc/html/index.html.

Please refer to CONTRIBUTING.md.

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