ESP32C3

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_dev_index.json

//***************************************************************/
//
//           -------------------------------------------
//           board: ESP32C3 Dev Module
//           Flash Mode: "DIO"
//           -------------------------------------------
//
//***************************************************************/

#define     LED_D4     12
#define     LED_D5     13

void setup() {

  Serial.begin(115200);
  pinMode(LED_D4, OUTPUT);
  pinMode(LED_D5, OUTPUT);

}

void loop() {

  Serial.println("Hello world!");

  digitalWrite(LED_D4, LOW);
  digitalWrite(LED_D5, HIGH);
  delay(500);
  digitalWrite(LED_D4, HIGH);
  digitalWrite(LED_D5, LOW);
  delay(500);

}