3.1. PWM - Breathing LED

This demo is based on PWM polling mode.

3.1.1. Hardware Connection

This demo is based on BL706_IOT, and the connection method is as follows

   GPIO function         GPIO pin
----------------------------------
    PWM_CH2      <-->     GPIO22

3.1.2. Software Implementation

-See examples/pwm/pwm_breath_led for the software code

#define BSP_PWM_CLOCK_SOURCE  ROOT_CLOCK_SOURCE_XCLK
#define BSP_PWM_CLOCK_DIV  1

Configure the PWM device clock source, see bsp/board/bl706_iot/clock_config.h

1#define CONFIG_GPIO22_FUNC GPIO_FUN_PWM

Configure PWM device multiplexing pins, see bsp/board/bl706_iot/pinmux_config.h

#define BSP_USING_PWM_CH2

#if defined(BSP_USING_PWM_CH2)
#ifndef PWM_CH2_CONFIG
#define PWM_CH2_CONFIG \
{   \
    .ch = 2, \
    .frequency = 1000000, \
    .dutycycle = 0, \
    .it_pulse_count = 0,\
}
#endif
#endif

Enable BSP_USING_PWM_CH2 and configure PWM device configuration, see bsp/board/bl706_iot/peripheral_config.h

pwm_register(PWM_CH2_INDEX, "led_breath", DEVICE_OFLAG_RDWR);

struct device *led_breath = device_find("led_breath");

if (led_breath) {
    PWM_DEV(led_breath)->period = 32; //frequence = 32M/1/32 = 1Mhz
    PWM_DEV(led_breath)->threshold_low = 16;
    PWM_DEV(led_breath)->threshold_high = 32;
    device_open(led_breath, DEVICE_OFLAG_STREAM_TX);
    pwm_channel_start(led_breath);
}

First call the pwm_register function to register a channel of the PWM device, currently register PWM_CH2
Then use the find function to find the handle corresponding to the device and save it in the led_breath handle
Set the frequency of PWM_CH2 to 1Mhz, and the duty cycle to 50%
Use device_open to open the led_breath device in polling mode

    for (pwm_cfg.threshold_high = 0; pwm_cfg.threshold_high <= 32; pwm_cfg.threshold_high++) {
        device_control(led_breath, DEIVCE_CTRL_PWM_DUTYCYCLE_CONFIG, &pwm_cfg);
        bflb_platform_delay_ms(50);
    }

    for (pwm_cfg.threshold_high = 32; 0 <= pwm_cfg.threshold_high && pwm_cfg.threshold_high <= 32; pwm_cfg.threshold_high--) {
        device_control(led_breath, DEIVCE_CTRL_PWM_DUTYCYCLE_CONFIG, &pwm_cfg);
        bflb_platform_delay_ms(50);
    }

Use the device_contorl function with the DEIVCE_CTRL_PWM_DUTYCYCLE_CONFIG instruction to modify the duty cycle of the current PWM channel.

3.1.3. Compile and Program

CDK compilation

Open project:pwm_breath_led.cdkproj

Refer to the steps of Guide to using CDK (like MDK Keil) under Windows to compile and download
Command compilation

 $ cd <sdk_path>/bl_mcu_sdk
 $ make BOARD=bl706_iot APP=pwm_breath_led

Program

See BLDevCube start guide

3.1.4. Experimental Phenomena

pwm breath led!

Video display: