Triggerbox

triggerbox - camera triggering for synchronized multi-camera setups

Principle of operation

Cameras trigger inputs are connected to pin D9 on an Arduino. (Optionally, a buffer amplifier can be used. See below for why this may be a good idea.) This is used to generate a digital pulse which triggers image acquisition on cameras. Furthermore, a host PC communicates with the Arduino to build a live model of the clocks on both systems and allows very precise (sub-millisecond) determination of the timing of trigger pulses from the Arduino. This allows precise timing information to be taken from the resulting acquired image frames.

Required hardware:

The minimal required hardware is this:

• Arduino Nano A000005 (later models WILL NOT WORK).

If using the minimal hardware, you will need to connect pin D9 to the trigger inputs of your camera directly.

Optional buffer amplified and circuit board:

For additional robustness for multi-camera setups, particularly those that have an opto-coupled trigger input which accordingly draws substantially more current, you will want a buffer amplifier to trigger more cameras. In the hardware_v1 and hardware_v2 directories are the PCB layouts, schematics, and enclosure of the triggerbox.

• Hardware_v1: BNC outputs for triggering only
• Hardware_v2: 4-pin terminal block ouputs for triggering and powering the cameras via external powersource.

Firmware Build and Install

This firmware can be compiled and installed with the Arduino IDE or at the command line.

Option 1: Compiling and Uploading using the Arduino IDE

The file triggerbox.ino can be opened directly in the Arduino IDE. Set your board to Arduino Nano ("Tools"->"Board"->"Arduino Nano"). Set your port ("Tools"->"Port") correctly, which depends on your specific computer setup. Then click the "Upload" button.

Option 2: Command-line Compiling and Uploading using Arduino CLI

To build this firmware for an Arduino Nano on Ubuntu linux, do the following steps.

Install the required software:

Intall Arduino CLI, then:

arduino-cli core update-index
arduino-cli core install arduino:avr

Compile the firmware

arduino-cli compile --fqbn arduino:avr:nano

Upload the firmware

# Note the port `/dev/ttyUSB0` may be different on your computer. In Windows,
# it will be something like `COM4`.
arduino-cli upload --port /dev/ttyUSB0 --fqbn arduino:avr:nano

Testing with host PC

Run the standalone demo program on your host PC.

• Prerequisite 1: install rust.
• Prerequisite 2 (linux only): make sure you are in the dialout group (or whichever group owns the device file - /dev/ttyUSB0 in the example below): sudo adduser `whoami` dialout.

The demo can be run like this:

cd braid-triggerbox-rs
# You may need to change the device path from `/dev/ttyUSB0` in this example.
# On Windows, this will be something like `COM4` instead of `/dev/ttyUSB0`.
cargo run -- --device /dev/ttyUSB0 --fps 100

If successful, the output will look like:

Requested 100 fps, using 100 fps
Connecting to trigger device ..
got new time model: None
.. connected.
got new time model: Some(ClockModel { gain: 0.009991053259000182, offset: 1642089273.653188, residuals: 0.00008373855939680652, n_measurements: 5 })
got new time model: Some(ClockModel { gain: 0.009990740683861077, offset: 1642089273.65347, residuals: 0.00008408054048913982, n_measurements: 6 })
got new time model: Some(ClockModel { gain: 0.009990941849537194, offset: 1642089273.6532729, residuals: 0.00008470585419217969, n_measurements: 7 })
got new time model: Some(ClockModel { gain: 0.0099910874851048, offset: 1642089273.6531227, residuals: 0.00008554253827242064, n_measurements: 8 })
got new time model: Some(ClockModel { gain: 0.009991202969104052, offset: 1642089273.652988, residuals: 0.0000863512614728279, n_measurements: 9 })
got new time model: Some(ClockModel { gain: 0.009991223458200693, offset: 1642089273.652963, residuals: 0.00008639545796995662, n_measurements: 10 })
got new time model: Some(ClockModel { gain: 0.009991292201448232, offset: 1642089273.6528616, residuals: 0.00008692377247143668, n_measurements: 11 })
got new time model: Some(ClockModel { gain: 0.009991496510338038, offset: 1642089273.6525416, residuals: 0.00009343214287582668, n_measurements: 12 })

License

Apache 2.0 or MIT at your choice. See LICENSE-APACHE and LICENSE-MIT.