Tutorial-Raspberry-Pi-cam-gps-andmore.github.io

Guide: GPS-Triggered Camera on Raspberry Pi

This guide explains how to set up your Raspberry Pi to take a photo that is precisely synchronized with a GPS time pulse (PPS), and then embed the GPS coordinates into the photo’s EXIF data.

Part 1: Hardware Setup

You will need a Raspberry Pi, a Pi Camera Module, and a GPS module that has a PPS (or 1PPS) output pin.

Connect the Pi Camera:
- Connect the camera ribbon cable to the CSI port on your Raspberry Pi. Ensure the blue tab on the cable faces the Ethernet/USB ports.
Connect the GPS Module:
- Power: Connect the GPS module’s VCC to a 3.3V pin on the Pi and GND to a Ground pin.
- Serial (UART): This is for reading the GPS location data (NMEA sentences).
  - Connect the GPS TX (Transmit) pin to the Pi’s RX (Receive) pin (GPIO 15).
  - Connect the GPS RX (Receive) pin to the Pi’s TX (Transmit) pin (GPIO 14).
- PPS Signal: This is for the high-precision timing trigger.
  - Connect the GPS module’s PPS output pin to GPIO 17 on the Raspberry Pi.

Pinout Summary (Physical Pins on Pi Header):

GPS Pin	Pi Pin (Physical)	Pi Pin (BCM)	Purpose
VCC	1 (3.3V Power)	-	Power for GPS
GND	6 (Ground)	-	Common Ground
TX	10 (GPIO 15)	GPIO 15	GPS data to Pi (RXD)
RX	8 (GPIO 14)	GPIO 14	Pi commands to GPS (TXD)
PPS	11 (GPIO 17)	GPIO 17	1 pulse-per-second signal

Part 2: Software & Dependencies

Enable Pi Interfaces:
- Open the configuration tool in your terminal: sudo raspi-config
- Navigate to Interface Options.
- Enable I1 Legacy Camera.
- Enable I5 Serial Port (disable login shell, enable hardware port).
- Finish and reboot if prompted.
Install System-level Libraries:
- The picamera2 and gpiod libraries have deep integration with the OS, so they should be installed globally using apt.
```
sudo apt update
sudo apt install -y python3-picamera2 python3-gpiod
```
Set up the Python Virtual Environment:
- Navigate to the directory where capture_with_gps.py is saved.
- Create the virtual environment:
```
python3 -m venv venv
```
- Activate the environment:
```
source venv/bin/activate
```
  Your prompt will now start with (venv).
Install Python Libraries:
- With the venv active, install the remaining libraries using pip. They will be installed safely inside your project’s venv folder.
```
pip install pyserial pynmea2 piexif
```

Part 3: The Python Script

The script capture_with_gps.py has been created for you. Here is a brief explanation of how it works:

Multithreading: It starts a background thread that only listens for and parses GPS data from the serial port. This prevents the main part of the program from getting stuck waiting for serial data.
PPS Trigger: The main thread monitors GPIO 17. When the GPS module gets a satellite lock, it sends out a very sharp electrical pulse once per second on the PPS pin. The script detects the “rising edge” of this pulse.
Capture & EXIF: As soon as the pulse is detected, the script tells the camera to take a picture. It then grabs the most recent GPS data collected by the background thread, formats it correctly, and injects it into the JPEG’s EXIF metadata before saving the file.
Configuration: You can easily change the GPIO pin, serial port, or output directory at the top of the script. Note: The script is set for a Raspberry Pi 5 (gpiochip4). If you use a Pi 4 or older, you must change Chip('gpiochip4') to Chip('gpiochip0').

Part 4: How to Run the Script

Get a GPS Fix: Take your Raspberry Pi somewhere with a clear view of the sky. The GPS module’s indicator light should start blinking, signifying it has a satellite lock. This can take a few minutes.
Check for GPS Data (Optional): You can “listen” to the serial port to see the raw NMEA data from the GPS module:
```
cat /dev/ttyS0
```
You should see lines starting with $GPRMC, $GPGGA, etc. Press Ctrl+C to stop.
Run the Python Script:
- Navigate to the directory where the script is saved.
- Activate the virtual environment:
```
source venv/bin/activate
```
- Execute the script:
```
python capture_with_gps.py
```
Output:
- The script will first wait for a valid GPS fix from the background thread.
- Once it has a fix, it will print “Monitoring GPIO pin…”.
- Each time a PPS pulse is received (once per second), it will take a photo and save it to the gps_photos directory.
- Press Ctrl+C to stop the script gracefully. When you are done, you can leave the environment by typing deactivate.

You can then view the photos in the gps_photos folder and check their properties/details to see the embedded GPS coordinates.