Key Takeaways
- TimeTagger enables precise event and reaction time measurement in Python
- It can interface with buttons, lights, sensors, and more when connected to the Pi’s GPIO pins
- After installation, scripts can be written to utilize TimeTagger for neuroscience and psychology experiments
- Optimization ideas include calculating statistics, integrating other hardware, adding visualization, building randomized protocols, and configuration files
TimeTagger is an open-source time-tagging Python library that can be used for building neuroscience experiments on the Raspberry Pi. It allows you to precisely record the timing of external events, making it useful for designing reaction time tests, animations, and more.
This guide will walk through the full process of installing and configuring TimeTagger for use with a Raspberry Pi.
Table of Contents
Hardware and Software Requirements
- Raspberry Pi board (3B+ recommended)
- 8GB+ SD card loaded with Raspberry Pi OS
- TimeTagger Python library
- External hardware to integrate (buttons, LEDs, etc.)
Installing Required Packages
We first need to update our Pi’s package list and install some dependencies that TimeTagger relies on:
sudo apt update
sudo apt install python3-numpy python3-scipy python3-matplotlib python3-pipInstalling the TimeTagger Library
Next we’ll install TimeTagger itself using pip:
python3 -m pip install timetaggerThis will download and install the latest version of the library.
Connecting External Hardware
Now we can hook up any buttons, lights, sensors or other hardware we want to tag events for. As an example, we’ll connect a basic button with a long cable.
Carefully connect one end to a ground pin and the other to a GPIO input pin on the Pi. When pressed, this will allow us to detect an external “event” that can be timed by our Python script.
Writing the Python Script
With everything set up, we can now write a simple Python script to test out TimeTagger functionality:
python
import timetagger as tt
button = tt.DIO(pin='GPIO25')
tage = tt.TagEventGenerator(button)
tage.start()
print(tage.wait())
tage.stop()This initializes a digital input on pin GPIO25, starts a TagEventGenerator listening to that input, prints any events detected, and finally stops monitoring.
When we press the button, the time of the event should be printed out in seconds relative to when monitoring was started!
We can build on this simple foundation to make all kinds of interactive experiments.
Optimizing the Script
From here, consider ways to optimize the script:
- Add functions to calculate reaction times or intervals between events
- Integrate with other GPIO devices like LEDs or sensors
- Build a graphical interface with matplotlib visualizations
- Create experiments utilizing random orders and timing
- Implement a full study protocol with config files
The possibilities are wide open when leveraging TimeTagger on a Raspberry Pi!
Combining the timing precision of TimeTagger with the GPIO connectivity of a Raspberry Pi provides a versatile platform for DIY experiments.
Conclusion
Setting up TimeTagger on a Raspberry Pi only takes a few steps, but opens up many options for building interactive and configurable experiments. This guide covered the installation process, GPIO hardware integration, script writing, and optimization ideas to serve as a starting point for your own projects.
The source code is openly available as well to adapt however you would like. With some creativity, the possibilities are endless for leveraging TimeTagger and a Pi to carry out customizable psychology and neuroscience studies!
FAQs
- What hardware can I interface with TimeTagger on the Pi?
You can connect buttons, LEDs, sensors, displays, servos, and more to the Pi’s GPIO pins. Anything that can generate or react to a digital input or output. - How accurate is the timing and tagging of events?
TimeTagger relies on the underlying latency of the Raspberry Pi’s Linux system, but generally can time events with 1-10 millisecond accuracy. - Can I connect multiple buttons at once?
Yes, TimeTagger supports monitoring multiple digital input lines simultaneously in the same script. - Is there example code available for TimeTagger projects?
Yes, lots of usage examples are available in the GitHub repository and documentation site for TimeTagger. - How do I get TimeTagger events into Python variables to analyze?
The wait() function returns a Python list of tagged events that can be processed further in your code. - Can I generate randomized event sequences?
Definitely, you can programmatically generate randomized orders and timing of outputs to GPIO devices. - Is MATLAB supported for visualizing data?
TimeTagger explicitly supports integration with MATLAB analyses and visualizations. - Can I create multiple experimental conditions programmatically?
Yes, you have full control in Python to create different branches and conditions by leveraging functions, lists, loops etc. - How long can I run an experiment for?
There’s no set limit – it depends on your specific study protocol and hardware capabilities. - Can I save the timestamp data to files?
You can write the time-stamped events to any number of file formats like CSV for later analysis. - Is Raspberry Pi OS required or can I use another Linux distribution?
Raspberry Pi OS is recommended but any Debian-based Linux distro should work fine as well. - Do I need the Raspberry Pi 4 model or can I use an older board?
The Pi 3B+ or newer is recommended for performance reasons. TimeTagger can even work on a Pi Zero but benchmarks slower. - Is special hardware required for maximum timing accuracy?
For the most precise sub-millisecond tagging, you may eventually want to explore FPGA add-on boards and oscillators. - Can I contribute improvements back to the TimeTagger project?
Yes! The source code is open source and available on GitHub for contributions from the community.
