T-TWR Plus Quick Start

Required Libraries

Library	Version	Source
RadioLib	Latest	GitHub
TinyGPSPlus	Latest	GitHub
U8g2	Latest	GitHub
XPowersLib	Latest	GitHub

Important: Always connect the RF antenna before powering on.

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Arduino

PlatformIO (Recommended)

1. Install VS Code and the PlatformIO IDE extension
2. Clone the repository:

   git clone https://github.com/Xinyuan-LilyGO/T-TWR.git

3. Open platformio.ini and uncomment the T-TWR-Plus environment
4. Click ✓ to build, connect via USB-C, click → to upload

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Arduino IDE

Board Settings

Setting	Value
Board	ESP32S3 Dev Module
Upload Speed	921600
USB CDC On Boot	Enabled
CPU Frequency	240 MHz (WiFi)
Flash Mode	QIO 80 MHz
Flash Size	16 MB (128Mb)
Partition Scheme	16M Flash (3MB APP/9.9MB FATFS)
PSRAM	OPI PSRAM

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Peripheral Examples

SA868 VHF/UHF Radio (AT commands)

// SA868 UART — check T-TWR-Plus schematic for exact pins
HardwareSerial sa868(1);

void setup() {
  Serial.begin(115200);
  sa868.begin(9600, SERIAL_8N1, /*RX=*/16, /*TX=*/15);
  delay(500);
  // Query firmware version
  sa868.println("AT+DMOCONNECT");
  delay(200);
  while (sa868.available()) Serial.write(sa868.read());
}

void loop() {}

GPS (via TinyGPSPlus)

#include <TinyGPSPlus.h>

TinyGPSPlus gps;
HardwareSerial gpsSerial(2);

void setup() {
  Serial.begin(115200);
  gpsSerial.begin(9600, SERIAL_8N1, /*RX=*/3, /*TX=*/1);
}

void loop() {
  while (gpsSerial.available()) gps.encode(gpsSerial.read());
  if (gps.location.isUpdated()) {
    Serial.printf("Lat: %.6f Lng: %.6f\n",
      gps.location.lat(), gps.location.lng());
  }
}

OLED Display (U8g2)

#include <U8g2lib.h>
#include <Wire.h>

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);

void setup() {
  u8g2.begin();
}

void loop() {
  u8g2.clearBuffer();
  u8g2.setFont(u8g2_font_ncenB08_tr);
  u8g2.drawStr(0, 20, "T-TWR Plus Ready");
  u8g2.sendBuffer();
  delay(1000);
}

PMU (AXP2101 via XPowersLib)

#include <XPowersLib.h>

XPowersPMU pmu;

void setup() {
  Serial.begin(115200);
  Wire.begin();
  if (!pmu.begin(Wire, AXP2101_SLAVE_ADDRESS)) {
    Serial.println("PMU init failed");
    return;
  }
  Serial.printf("Battery: %d mV\n", pmu.getBattVoltage());
}

void loop() { delay(1000); }

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FAQ

Q: Upload keeps failing?
A: Hold BOOT, press and release RST, then release BOOT to enter download mode.

Q: What is the difference from T-TWR?
A: T-TWR Plus adds enhanced battery capacity, upgraded PMU, and additional I/O compared to the standard T-TWR.