FireBeetle 2 ESP32 C6开发板 PWM应用

尹小舟

FireBeetle 2 ESP32 C6开发板 PWM应用 [复制链接]

 

      在Arduino UNO控制器中，调用analogWrite()函数输出PWM 来控制LED的亮度, 或者控制电机的转速.,在ESP32 C6 Arduino并没有直接实现analogWrite()函数，而且ESP32的PWM更加复杂，Arduino提供的接口并不满足控制PWM的需求。ESP32提供了LEDC（LED Control）库来管理PWM信号，这允许更高级的控制，包括更高的分辨率和多个通道的并发使用。

     下面我们来看下ESP32 在Arduino的代码

 

void analogWrite(uint8_t pin, int value) {
  // Use ledc hardware for internal pins
  if (pin < SOC_GPIO_PIN_COUNT) {
    ledc_channel_handle_t *bus = (ledc_channel_handle_t*)perimanGetPinBus(pin, ESP32_BUS_TYPE_LEDC);
    if(bus == NULL && perimanClearPinBus(pin)){
        if(ledcAttach(pin, analog_frequency, analog_resolution) == 0){
            log_e("analogWrite setup failed (freq = %u, resolution = %u). Try setting different resolution or frequency");
            return;
        }
    }
    ledcWrite(pin, value);
  }
}

我们发现ESP三二对arduino的PWM接口做了适配

函数前面定义了两个变量

static uint8_t analog_resolution = 8;
static int analog_frequency = 1000;

 

所以使用analogWrite()会产生一个1K HZ 8bit分辨率的PWM

 

ledcWrite() 函数并不是直接接受一个GPIO引脚号（pin）作为参数，而是接受一个LEDC通道号（channel）和一个值（value）。这是因为ESP32的LEDC（LED Control）库使用通道的概念来管理PWM信号，而不是直接绑定到特定的GPIO引脚。

函数原型如下：

                  bool ledcWrite(uint8_t pin, uint32_t duty)

 

• pin：PWM输出引脚
• duty：PWM的占空比值，它的范围取决于函数中设置的分辨率（resolution）。

 

在这些设备中，IO MUX用于将GPIO（通用输入输出）引脚配置为不同的功能，如PWM输出、I2C通信、UART串行通信等。

IO MUX通常用于将GPIO引脚配置为不同的功能；

ledcWrite()的 Pin 可能可以设置为任意数字IO

 

 

void analogWriteFrequency(uint8_t pin, uint32_t freq) {
    if (ledcChangeFrequency(pin, freq, analog_resolution) == 0){
        log_e("analogWrite frequency cant be set due to selected resolution! Try to adjust resolution first");
        return;
    }
    analog_frequency = freq;
}

默认PWM分辨率8 bit

改变给定引脚的频率

 

void analogWriteResolution(uint8_t pin, uint8_t resolution) {
    if (ledcChangeFrequency(pin, analog_frequency, resolution) == 0){
        log_e("analogWrite resolution cant be set due to selected frequency! Try to adjust frequency first");
        return;
    }
    analog_resolution = resolution;
}

改变给定引脚的PWM分辨率

 

代码测试

 

void setup() {
  analogWriteFrequency(D2,10000);
  analogWriteFrequency(D13,10000);
  analogWrite(D2,25);
  analogWrite(D13,100);
}

void loop() {
  
}

 

和设置不符合

void setup() {
  analogWrite(D2,25);
  analogWrite(D13,100);
  analogWriteFrequency(D2,10000);
  analogWriteFrequency(D13,10000);
}

void loop() {
  
}

 

 

符合设计

 

@brief  为给定的LEDC引脚设置输出信号的反转。","marks":[]}]}],"state":{"index":1}},{"type":"block","id":"IciE-1715321995887","name":"list-item","data":{"listId":"DS8H-1715321995894","listLevel":1,"listType":"unordered","style":{},"version":1},"nodes":[{"type":"text","id":"69OR-1715321995886","leaves":[{"text":"@param pin GPIO引脚","marks":[]}]}],"state":{"index":2}},{"type":"block","id":"3KPs-1715321995889","name":"list-item","data":{"listId":"DS8H-1715321995894","listLevel":1,"listType":"unordered","style":{},"version":1},"nodes":[{"type":"text","id":"QU50-1715321995888","leaves":[{"text":"@param out_invert 选择是否反转输出（true = 输出反转）。","marks":[]}]}],"state":{"index":3}},{"type":"block","id":"BktE-1715321995893","name":"list-item","data":{"listId":"DS8H-1715321995894","listLevel":1,"listType":"unordered","style":{},"version":1},"nodes":[{"type":"text","id":"k8yX-1715321995892","leaves":[{"text":"@return  如果成功设置了输出反转，返回true；否则返回false。","marks":[]}]}],"state":{"index":4}},{"type":"block","id":"3lLD-1715322029971","name":"paragraph","data":{},"nodes":[{"type":"text","id":"KabB-1715322029970","leaves":[{"text":"**/","marks":[]}]}],"state":{"index":5}},{"type":"block","id":"yLyA-1715321639881","name":"paragraph","data":{"style":{}},"nodes":[{"type":"text","id":"qSfU-1715321639879","leaves":[{"text":"bool ledcOutputInvert(uint8_t pin, bool out_invert);","marks":[]}]}],"state":{}}]">

/**

• @brief 为给定的LEDC引脚设置输出信号的反转。
• @param pin GPIO引脚
• @param out_invert 选择是否反转输出（true = 输出反转）。
• @return 如果成功设置了输出反转，返回true；否则返回false。

**/

bool ledcOutputInvert(uint8_t pin, bool out_invert);

 

void setup() {
  analogWrite(D2,25);
  analogWrite(D13,100);
  analogWriteFrequency(D2,10000);
  analogWriteFrequency(D13,10000);
  ledcOutputInvert(D2,true);
}

void loop() {
  
}

 

总结：

      虽然可以通过Arduino输出PWM,但是接口并不完善，使用者最好还是要使用LEDC（LED Control）库来开发

Jacktang

用LEDC（LED Control）库来开发，能避免Arduino输出PWM,但是接口并不完善的问题么

尹小舟

Jacktang 发表于 2024-5-11 07:30 用LEDC（LED Control）库来开发，能避免Arduino输出PWM,但是接口并不完善的问题么

可以的 LEDC 封装的接口更多