Tag Archives: ESP32-C6

Seeedstudio XIAO ESP32 S3 RS-485 test harness(Arduino)

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As part of a project to read values from a MODBUS RS-485 sensor using a RS-485 Breakout Board for Seeed Studio XIAO and a Seeed Studio XIAO ESP32-S3 I built the test harness described in the wiki post. The test harness setup for a Seeed Studio XIAO ESP32-C3/Seeed Studio XIAO ESP32-C6 didn’t work with my Seeed Studio XIAO ESP32-S3.

I then did some digging looked at schematics and figured out the port mappings were different. This took a while so I tried Microsoft Copilot

I then updated the port assigned for my RS485Sender application

#include <HardwareSerial.h>

HardwareSerial RS485(1);

#define enable_pin D2

void setup() {
  Serial.begin(9600);  // Initialize the hardware serial with a baud rate of 115200
  delay(5000);

  Serial.println("RS485 Sender");

  // Wait for the hardware serial to be ready
  while (!Serial)
    ;
  Serial.println("!Serial done");

  //mySerial.begin(115200, SERIAL_8N1, 7, 6); // RX=D4(GPIO6), TX=D5(GPIO7) Doesn't work
  RS485.begin(115200, SERIAL_8N1, 6, 5);

  // Wait for the hardware serial to be ready
  while (!RS485)
    ;
  Serial.println("!RS485 done ");

  pinMode(enable_pin, OUTPUT);     // Set the enable pin as an output
  digitalWrite(enable_pin, HIGH);  // Set the enable pin to high
}

void loop() {
  if (Serial.available()) {
    String inputData = Serial.readStringUntil('\n');  // Read the data from the hardware serial until a newline character

    // If the received data is not empty
    if (inputData.length() > 0) {
      Serial.println("Send successfully");  // Print a success message
      RS485.println(inputData);             // Send the received data to the hardware serial
    }
  }
}

I then updated the port assigned for my RS485Receiver application

#include <HardwareSerial.h>

HardwareSerial RS485(1);  // Use UART2
#define enable_pin D2

void setup() {
  Serial.begin(9600);  // Initialize the hardware serial with a baud rate of 115200
  delay(5000);

  Serial.println("RS485 Receiver");

  // Wait for the hardware serial to be ready
  while (!Serial)
    ;
  Serial.println("!Serial done");

  // mySerial.begin(115200, SERIAL_8N1, 7, 6); // RX=D4(GPIO6), TX=D5(GPIO7) Doesn't seem to work
  RS485.begin(115200, SERIAL_8N1, 6, 5); 
  
    // Wait for the hardware serial to be ready
  while (!RS485)
    ;
  Serial.println("!RS485 done ");

  pinMode(enable_pin, OUTPUT);    // Set the enable pin as an output
  digitalWrite(enable_pin, LOW);  // Set the enable pin to low
}

void loop() {
  // Check if there is data available from the hardware serial
  int x = RS485.available();

  if (x) {
    String response = RS485.readString();

    Serial.println(" RS485 Response: " + response);
  }

  delay(1000);
}

Getting my test harness RS485Sender and RS485Receiver applications (inspired by Seeedstudio wiki) took quite a bit longer than expected. Using Copilot worked better than expected but I think that might be because after doing some research my prompts were better.