Overview

The PA1010D is an ultra-compact 99-channel multi-GNSS (GPS, GLONASS, GALILEO, QZSS) receiver module manufactured by GlobalTop and popularized by Adafruit on STEMMA QT breakout boards. Measuring just $12\text{ mm} \times 12\text{ mm}$, it integrates a high-sensitivity MediaTek MTK3333 GNSS chipset and an internal ceramic patch antenna.

Unlike traditional GPS modules (such as the NEO-6M) that communicate strictly over UART, the PA1010D supports both standard TTL UART (9,600 bps) and $I^2C$ (0x10), allowing microcontrollers without spare hardware serial ports to read NMEA-0183 GPS sentences easily. With $-165\text{ dBm}$ tracking sensitivity and up to 10 Hz position update rates, it is ideal for compact wearable trackers, drone telemetry, and high-altitude balloon payloads.

Quick reference

Pinout

STEMMA QT / Qwiic 4-pin connector & 0.1" header pins:

Specifications

$I^2C$ NMEA Streaming Protocol

When interfaced over $I^2C$ (0x10), the PA1010D continuously streams standard ASCII NMEA-0183 sentences ($GPRMC, $GPGGA, $GPGSA, $GPGSV):

• Reading from address 0x10 returns available NMEA characters.
• If no new data is ready, the module returns 0x0A (\n newline).

$GPRMC,123519.00,A,4807.038,N,01131.000,E,022.4,084.4,230326,003.1,W*6A
$GPGGA,123519.00,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47

Wiring

Example (Arduino Adafruit_GPS over $I^2C$)

#include <Adafruit_GPS.h>

// Initialize I2C GPS instance
Adafruit_GPS GPS(&Wire);

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10);

  Serial.println("Adafruit PA1010D I2C GPS Test");

  // 0x10 is default I2C address for PA1010D
  GPS.begin(0x10);

  // Request RMC and GGA NMEA sentences and 1 Hz update rate
  GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);

  delay(1000);
}

void loop() {
  // Read NMEA data from I2C bus
  char c = GPS.read();
  if (GPS.newNMEAreceived()) {
    if (!GPS.parse(GPS.lastNMEA())) return;

    if (GPS.fix) {
      Serial.print("Location: ");
      Serial.print(GPS.latitudeDegrees, 4); Serial.print(", ");
      Serial.print(GPS.longitudeDegrees, 4);
      Serial.print(" | Altitude: "); Serial.print(GPS.altitude); Serial.println(" m");
    } else {
      Serial.println("Searching for satellite lock...");
    }
  }
}

Common mistakes

• Testing indoors: GPS signals (1575.42 MHz) cannot penetrate concrete ceilings or metallic roofs. Always test initial satellite acquisition outdoors under clear sky.
• Occluding the ceramic patch antenna: Mount the PA1010D board horizontally with the square ceramic patch antenna facing upwards towards the sky. Do not cover with copper shields or batteries.

Notes

• PA1010D vs Ultimate GPS (MTK3339): PA1010D is significantly smaller ($12 \times 12\text{ mm}$ vs $16 \times 16\text{ mm}$), supports GLONASS in addition to GPS, and includes built-in $I^2C$ support.