ESPIDF-PWM

概述

ESP32 有两个模块可以产生PWM。一个是 MCPWM ，另一个是 LED_PWM。

MCPWM

电机控制脉宽调制器（MCPWM）外设用于电机和电源控制。它提供了六个 PWM 输出，可在几种拓扑结构中运行。常见的拓扑结构之一是用一对 PWM 输出来驱动 H 桥以控制电机旋转速度和旋转方向。
MCPWM 的时序和控制资源分为两种主要类型的模块：PWM 定时器和 PWM 操作器。每个 PWM 定时器提供定时参考，可以自由运行，或同步到其他定时器或外部源。每个 PWM 操作器具有用于为一个 PWM 通道生成波形对的所有控制资源。MCPWM 外设还包含专用捕获模块，用于需要精确定时外部事件的系统。
ESP32 有两个 MCPWM 外设，分别是 MCPWM0 和 MCPWM1。它们的控制寄存器分别位于从地址 0x3FF5E000 和 0x3FF6C000 开始的 4 KB 内存中。

LED_PWM

LED_PWM 主要用于控制 LED 的亮度和颜色，也可以产生 PWM 信号用于其他用途。LED_PWM 有 16 路通道，即 8 路高速通道和 8 路低速通道。这 16 路通道能够产生独立的数字波形来驱动 RGB LED 设备。高速或低速通道可以由四个高速定时器之一或四个低速定时器之一进行驱动。PWM 控制器还能够自动逐渐增加或减少占空比，在无须处理器干预的情况下实现亮度和颜色渐变。LED_PWM 还支持小数分频。

绑定gpio

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/**
 * @brief This function initializes each gpio signal for MCPWM
 *
 * @note This function initializes one gpio at a time.
 *
 * @param mcpwm_num set MCPWM unit(0-1)
 * @param io_signal set MCPWM signals, each MCPWM unit has 6 output(MCPWMXA, MCPWMXB) and 9 input(SYNC_X, FAULT_X, CAP_X)
 *                  'X' is timer_num(0-2)
 * @param gpio_num set this to configure gpio for MCPWM, if you want to use gpio16, gpio_num = 16
 *
 * @return
 *     - ESP_OK Success
 *     - ESP_ERR_INVALID_ARG Parameter error
 */
esp_err_t mcpwm_gpio_init(mcpwm_unit_t mcpwm_num, mcpwm_io_signals_t io_signal, int gpio_num);

mcpwm初始化

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/**
 * @brief Initialize MCPWM parameters
 * @note
 *        The default resolution configured for MCPWM group and timer are 160M / 16 = 10M and 10M / 10 = 1M
 *        The default resolution can be changed by calling mcpwm_group_set_resolution() and mcpwm_timer_set_resolution(),
 *        before calling this function.
 *
 * @param mcpwm_num set MCPWM unit(0-1)
 * @param timer_num set timer number(0-2) of MCPWM, each MCPWM unit has 3 timers.
 * @param mcpwm_conf configure structure mcpwm_config_t
 *
 * @return
 *     - ESP_OK Success
 *     - ESP_ERR_INVALID_ARG Parameter error
 */
esp_err_t mcpwm_init( mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num, const mcpwm_config_t  *mcpwm_conf);

当使用 mcpwm_init() 后，ESP32 会自动调用 mcpwm_start() 启动电机.

设置占空比

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/**
 * @brief Set duty cycle of each operator(MCPWMXA/MCPWMXB)
 *
 * @param mcpwm_num set MCPWM unit(0-1)
 * @param timer_num set timer number(0-2) of MCPWM, each MCPWM unit has 3 timers
 * @param gen set the generator(MCPWMXA/MCPWMXB), 'X' is operator number selected
 * @param duty set duty cycle in %(i.e for 62.3% duty cycle, duty = 62.3) of each operator
 *
 * @return
 *     - ESP_OK Success
 *     - ESP_ERR_INVALID_ARG Parameter error
 */
esp_err_t mcpwm_set_duty(mcpwm_unit_t mcpwm_num, mcpwm_timer_t timer_num, mcpwm_generator_t gen, float duty);