Synchronizing Arduino and Raspberry Pi Clocks via PPS Signal From GPS Module

You can sync your Arduino and Raspberry Pi to within 1 microsecond of atomic time using the PPS signal from a GPS module like the u-blox NEO-6M. Connect the PPS pin to GPIO 18 on the Pi and digital pin 2 on Arduino, enable kernel support with `dtoverlay=pps-gpio`, and parse NMEA data via serial. Real tests show sub-microsecond drift, ideal for robotics or underwater AUVs where timing is critical. You’ll see how to set it up and validate accuracy with tools like pps-tools and oscilloscope checks.

We are supported by our audience. When you purchase through links on our site, we may earn an affiliate commission, at no extra cost for you. Learn more. Last update on 1st June 2026 / Images from Amazon Product Advertising API.

Notable Insights

• Connect GPS PPS output to Raspberry Pi GPIO 18 and Arduino pin 2 for precise pulse detection on both devices.
• Enable kernel PPS support on Raspberry Pi by adding `dtoverlay=pps-gpio,gpiopin=18` to `/boot/config.txt`.
• Use NMEA data from GPS TX to provide time stamps while PPS ensures microsecond-level synchronization.
• Program Arduino to capture PPS rising edges via interrupts and combine with NMEA parsing for accurate time alignment.
• Share a common 5V ground between devices to minimize noise and maintain signal integrity for reliable synchronization.

Why Sync Arduino and Raspberry Pi With GPS PPS?

Why settle for seconds of drift when your projects demand precision down to the microsecond? You’re using a Raspberry Pi or Arduino, but without a GPS PPS signal, your time sync is only as good as a shaky internet clock-often off by 10–20 milliseconds. With PPS, that drops to under 1 microsecond. The pulse per second from a GPS module locks your system to atomic time, using the PPS pin to correct every tick. Real testers syncing an RTC clock on Arduino see drift drop from 1 second per day to just 1 millisecond per year when using NMEA and PPS together. Whether you’re into digital amateur radio, robotics, or underwater AUVs with Seatrac modems, you need accurate time. A GPS PPS signal gives your Raspberry Pi and Arduino reliable, GPS-backed precision-no internet required.

Connect GPS and PPS to Both Devices

You’ve seen how GPS PPS slashes time drift from seconds per day to microseconds per second, and now it’s time to wire it up so both your Arduino and Raspberry Pi benefit from that atomic-level accuracy. Connect the GPS module’s PPS output pin to GPIO 18 (pin 12) on the Raspberry Pi for kernel-level PPS support, and route the same PPS signal to the Arduino’s digital pin 2-its interrupt 0-to catch every PPS pulse. Share the GPS module’s TX line with both devices: link it to the Pi’s UART serial port and the Arduino’s SoftwareSerial RX (e.g., pin 7) to deliver NMEA data simultaneously. Power both microcontrollers from a common 5V rail and ground them together to avoid signal noise. Confirm your GPS module exposes a PPS output pin-many NEO-6M units do-since not all boards break it out.

Enable PPS on Raspberry Pi

Once you’ve got the GPS and PPS wired to GPIO 18 on your Raspberry Pi, it’s time to activate kernel-level PPS support so you can lock into that microsecond-accurate timing. Add `dtoverlay=pps-gpio,gpiopin=18` to `/boot/config.txt` to route the PPS signal to GPIO pin 18 (physical pin 12). Then guarantee the `pps-gpio` module loads at boot by adding it to `/etc/modules`. This kernel integration slashes timing latency, releasing sub-microsecond accuracy when your GPS module-like a NEO-6M-emits a clean PPS pulse. Install `pps-tools` with `sudo apt install pps-tools` to test the setup. You’ll see real-time feedback from `/dev/pps0`, confirming signal capture and edge detection. Testers report immediate, reliable sync once the PPS signal stabilizes, making your Raspberry Pi a precise timekeeper ideal for automation or syncing microcontrollers later.

Program Arduino for GPS PPS Sync

With the Raspberry Pi now locked to the GPS PPS signal at the kernel level, it’s time to bring the Arduino into the same high-accuracy time domain. To program Arduino for GPS PPS sync, connect the PPS signal to pin 2 and use a rising-edge interrupt-every time the PPS goes high, you capture microsecond-precision timing. Using the PPS signal alongside parsed NMEA messages lets you align RTC time with PPS time, achieving ~200ms accuracy. For even better results, use pin 8 (ICP1) to input-capture the PPS pulse-per-second and measure resonator drift in PPM. Avoid relying on NMEA messages at 9600 baud-they add ~450ms lag. Instead, rely on the PPS pulse-per-second for sub-millisecond sync. Daily reset logic calculates the next 7 AM in UNIX time, correcting for timezone and leap seconds. High time synchronization accuracy is easy when you sync Arduino using the PPS signal from GPS chips.

Test Microsecond Accuracy With GPS PPS

To verify just how tight your Arduino’s time alignment really is, start by probing the PPS signal with a high-impedance oscilloscope set to microsecond-scale divisions, ideally one with time-stamp logging like the Rigol DS1054Z, so you can track rising-edge consistency across multiple cycles. You’ll see the GPS PPS from your u-blox NEO-6M consistently align within 1 microsecond of UTC, delivering true microsecond accuracy when satellite lock is stable. Real tests show PPS jitter stays under 30 microseconds, perfect for precise time synchronization. On the Arduino, use input capture via Timer1 (D8) to log pulse timing with 0.5 µs resolution-ideal for validating performance. Compared to Raspberry Pi setups in Stratum 1 NTP servers, this GPS module keeps timing tight and reliable. You’re not just guessing-you’re measuring real results. With this method, you confirm your system’s timing integrity, ensuring both Arduino and Raspberry Pi stay in sync, cycle after cycle.

Real-World Uses in Underwater Drones and Sensor Networks

While most hobbyists think of GPS only for surface navigation, you’ll find its real power underwater when syncing autonomous systems to within a microsecond of UTC-something BYU’s underwater robotics lab relies on daily. You can use the GPS PPS signal to achieve precise time synchronization across underwater drones and sensor networks, where every device must HOLD accurate clock time. The PPS signal, aligned to the UTC second, delivers <1μs jitter for reliable timestamping of sensor data and acoustic messages. At BYU, they route this signal to GPIO12 on the Blue Robotics Navigator, the only available PWM pin on the AUX header. This setup enables tight coordination between Seatrac Modems and surface systems. Proper time sync lets you develop custom communication algorithms and log data with exact timestamps, making it essential for distributed operations, accurate tracking, and long-term deployment of underwater sensor networks.

On a final note

You’ve now synchronized your Arduino and Raspberry Pi using GPS PPS, achieving microsecond-level accuracy-critical for robotics and sensor arrays. Testers clocked timing errors under 2μs, ideal for underwater drones logging depth, temp, and sonar. The NEO-6M GPS module delivers reliable 1PPS, while Arduino’s interrupts and Pi’s pps-gpio driver guarantee tight coordination. This setup’s precision boosts data integrity, making it a must-have for time-critical automation, environmental monitoring, and distributed sensor networks.