ESP32 DAC with web server

[cob555]

Hello all :-)

Currently I am trying to get a simple DAC up and running which is controlled by a web server.
This code was used as a template (and works fine): https://microcontrollerslab.com/esp32-pwm-slider-web-server-control-led-brightness/

This is the modified code (the LED-commands were deleted and DAC-commands added)

#define DAC_CH1 25

string slider_value = "0";

const char* input_parameter = "value";

AsyncWebServer server(80);

....web-server part is all the same....

String processor(const String& var){
  if (var == "SLIDERVALUE"){
    return slider_value;
  }
  return String();
}

void setup(){
  Serial.begin(115200);

  dacWrite(DAC_CH1, slider_value);
  Serial.println("DAC Value 0");

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting...");
  }
  Serial.println(WiFi.localIP());

  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send_P(200, "text/html", index_html, processor);
  });
  server.on("/slider", HTTP_GET, [] (AsyncWebServerRequest *request) {
    String message;
    if (request->hasParam(input_parameter)) {
      message = request->getParam(input_parameter)->value();
      slider_value = message;
      ledcWrite(DAC_CH1, slider_value.toInt());
    }
    else {
      message = "No message sent";
    }
    Serial.println(message);
    request->send(200, "text/plain", "OK");
  });
    server.begin();
}
  void loop() {}

Apparently there is problem with the definition of the variables and the compiler gives an error message.
"slider_value" is string, but DAC requires uint8_t as an input.
How can this problem be solved?

Thanks in advance.

[me-no-dev]

Two issue there:

1. You have dacWrite(DAC_CH1, slider_value); in the code and slider_value is string. Line should be dacWrite(DAC_CH1, slider_value.toInt());
2. In the /slider callback you have ledcWrite(DAC_CH1, slider_value.toInt());, but you want DAC, so change that to dacWrite(DAC_CH1, slider_value.toInt());

[cob555]

Thanks a lot. Very embarrassing, I totally overlooked the second command, which needed to be changed.
Now it works just as fine as the PWM-code.