Description

The Frame2TTL device uses an integrated optical sensor (AMS TSL235R) to measure the instant an LCD monitor updates its screen with a new frame. It generates a 5V TTL pulse when the patch of screen beneath its sensor switches between minimum and maximum intensity (for an example, see the PsychToolboxVideoServer plugin for Bpod). The output signal is used to precisely align the frames of a visual stimulus with concurrently acquired physiology and behavior measurements.

Specifications

Processor

• ARM Cortex M0: Atmel SAMD21 (open source Sparkfun breakout board, programmable as an Arduino Zero)
• 48MHz clock speed, 32-bit

Sensor

• AMS TSL235R
• TSL235R is a light to frequency converter. It toggles a logic line at a frequency proportional to light intensity. The interval between logic line transitions is then measured by the Cortex M0 microcontroller (above) to compute light intensity.

Sensor Mount

• Comprised of three 3D-printable arms and a pair of thumb screws.
• The mount clamps the sensor to the monitor face, blocking most ambient light.
• NOTE: The back surface of the monitor must be flat (not curved!) in order to use this mount without custom modification.
• Mount compatible with monitors up to 50mm thick.
• An alternative sensor arm (included) reaches around monitor bezels up to 5mm above the surface of the screen.

Output channel

• BNC connector; 5V TTL Logic

Latency

• Frame2TTL signals intensity changes in < 0.5ms (typical).

Power supply

• Derived from a USB A to B-micro cable (included)

MATLAB Software

• A MATLAB object allows configuration of light intensity thresholds for frame detection.
• A simple command streams the light sensor's output to the screen, to help identify application-specific light levels and to aid with setting frame detection thresholds.

Bpod PsychToolboxVideoServer plugin

• The PsychToolboxVideoServer plugin for Bpod presents video stimuli in a configurable portion of the screen, while displaying a small "sync" patch on the screen edge to drive Frame2TTL.
• The sync patch alternates between 0 intensity and maximum intensity with each frame change during playback, causing a corresponding TTL level change on Frame2TTL's BNC output channel.

Material safety

• All parts are RoHS Compliant in our professional builds

Dimensions

• L: 9.0cm (6")
• W: 9.0cm (6")
• H: 3.0cm (1 1/8")