• MCU programmed on this PCB: ESP32-WROOM-32E-N16
• Framework: Arduino for ESP32
• Build system: PlatformIO
• Functional link MCU: BU01 module internal STM32F103 communicates over UART2.

Ini
[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600

Cpp
#include <Arduino.h>
#include <WiFi.h>
#include <HTTPClient.h>

// ESP32 schematic pins
#define BU01_UART_RX_PIN 16   // GPIO16/U2RXD <- ESP_RX <- BU01 U1TX/PA9
#define BU01_UART_TX_PIN 17   // GPIO17/U2TXD -> ESP_TX -> BU01 U1RX/PA10

#define BU01_BAUD 115200
#define USB_DEBUG_BAUD 115200
#define BU01_POLL_INTERVAL_MS 1000

const char* WIFI_SSID = "YOUR_SSID";
const char* WIFI_PASSWORD = "YOUR_PASSWORD";
const char* UPLINK_URL = "http://192.168.1.100:8080/tee-marker";

HardwareSerial BU01Serial(2);
unsigned long lastPoll = 0;

void initWiFi() {
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.print("WiFi connecting");
  for (int i = 0; i < 30 && WiFi.status() != WL_CONNECTED; ++i) {
    delay(500);
    Serial.print('.');
  }
  Serial.println();
  if (WiFi.status() == WL_CONNECTED) {
    Serial.print("WiFi connected, IP=");
    Serial.println(WiFi.localIP());
  } else {
    Serial.println("WiFi not connected; continuing with UART bridge/debug only");
  }
}

void sendToUplink(const String& payload) {
  if (WiFi.status() != WL_CONNECTED) {
    initWiFi();
  }
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    http.begin(UPLINK_URL);
    http.addHeader("Content-Type", "application/json");
    int code = http.POST(payload);
    Serial.printf("HTTP POST code=%d\n", code);
    http.end();
  }
}

void setup() {
  Serial.begin(USB_DEBUG_BAUD);
  delay(200);
  Serial.println("Smart Tee Marker ESP32 uplink starting");

  BU01Serial.begin(BU01_BAUD, SERIAL_8N1, BU01_UART_RX_PIN, BU01_UART_TX_PIN);
  initWiFi();
}

void loop() {
  while (BU01Serial.available()) {
    String line = BU01Serial.readStringUntil('\n');
    line.trim();
    if (line.length() > 0) {
      Serial.print("BU01> ");
      Serial.println(line);
      String payload = String("{\"source\":\"bu01\",\"data\":\"") + line + "\"}";
      sendToUplink(payload);
    }
  }

  unsigned long now = millis();
  if (now - lastPoll >= BU01_POLL_INTERVAL_MS) {
    lastPoll = now;
    BU01Serial.println("STATUS?");
  }
}

1. Install PlatformIO.
2. Hold BOOT if auto-reset fails, then run: pio run -t upload.
3. Open monitor: pio device monitor -b 115200.
4. Confirm UART traffic from the BU01 module appears as BU01> lines.

• BU01 pin order is represented with a generic 2x12 socket and must be verified before final PCB layout.
• BU01 internal STM32 firmware is outside this ESP32 starter file; use the listed BU01 nets for STM32 firmware pin mapping.