How to use Serial1 with XIAO ESP32C3

Products & Technology XIAO
4

Luckily, I was able to use USB and UART0 at the same time. Of course, USB CDC on Boot is set to Enable. So I’ll share how I did it.

ESP-ROM:esp32c3-api1-20210207 Build:Feb 7 2021
Arduino core for the ESP32 v2.05
Arduino IDE 2.0.2

Note
In case of “CPU Frequency:160MHz”, it work correct, but in case of “CPU Frequency:40MHz”, it works at half the speed of what you set. This seems to be the cause.

/*   Multiple Serial test for XIAO ESP32C3 */
HardwareSerial MySerial(0);   //Create a new HardwareSerial class.

void setup() {
  // initialize both serial ports:
  Serial.begin(115200);
  MySerial.begin(115200, SERIAL_8N1, RX, TX); // at CPU Freq is 40MHz, work half speed of defined.

}

void loop() {
  // read from port 1, send to port 0:
  if (MySerial.available()) {
    String str  = MySerial.readStringUntil('\r');
    Serial.println(str);
  }

  // read from port 0, send to port 1:
  if (Serial.available()) {
    String str = Serial.readStringUntil('\r');
    MySerial.println(str);
  }

}

RX and TX is defined in arduino-esp32/variants/XIAO_ESP32C3/pins_arduino.h as below.

static const uint8_t TX = 21;
static const uint8_t RX = 20;
/* */
static const uint8_t D6 = 21;
static const uint8_t D7 = 20;
3 Likes