#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED setup
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_ADDRESS 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// RS485 control pins
#define DE_PIN 20
#define RE_PIN 10

void setup() {
  // Initialize Serial1 for RS485 (TX=21, RX=9)
  Serial.begin(115200);
  Serial1.begin(1000000, SERIAL_8N1, 9, 21);

  // Set DE and RE as outputs
  pinMode(DE_PIN, OUTPUT);
  pinMode(RE_PIN, OUTPUT);

  // Enable receive mode
  digitalWrite(DE_PIN, LOW);
  digitalWrite(RE_PIN, LOW);

  // Initialize OLED
  Wire.begin(3, 4);  // SDA=3, SCL=4
  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {
    while (true)
      ;  // Halt if display fails
  }
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("Waiting for RS485...");
  display.display();
}

void loop() {
  if (Serial1.available()) {
    uint8_t buffer[32];
    int count = 0;

    // Read all available bytes
    while (Serial1.available() && count < sizeof(buffer)) {
      buffer[count++] = Serial1.read();
    }

    // Display on Serial
    Serial.print("recv: ");
    for (int i = 0; i < count; i++) {
      Serial.print("0x");
      if (buffer[i] < 0x10) Serial.print("0");
      Serial.print(buffer[i], HEX);
      Serial.print(" ");
    }
    Serial.println();

    // Display on OLED
    display.clearDisplay();
    display.setCursor(0, 0);
    display.setTextSize(1);
    display.println("Received:");
    display.setCursor(0, 12);
    display.setTextSize(1);

    for (int i = 0; i < count; i++) {
      display.print("0x");
      if (buffer[i] < 0x10) display.print("0");
      display.print(buffer[i], HEX);
      display.print(" ");
    }
    display.display();
  }
}