A Game Boy ROM for measuring screen latency. Runs at 60 FPS. Triggering a screen change inverts the palette.
When you trigger the screen change, the ROM will attempt to turn on an attached LED. You can use the insideGadgets LED card, a Power Antenna / Bug Sensor, or the GBC's built in infared LED. You can film the screen and LED in slow motion together to roughly measure screen latency, and observe other aspects of the screen's performance.
led-screen-timer-demo.mp4
Q5 GBC kit filmed on iPhone SE 3rd Gen, 237 FPS
If you have the "Power Antenna" or "Bug Sensor" LED link port accessory, this rom will light it up on the screen transition.
The only off the shelf cart that is supported is the insideGadgets 512KB cart with LED. It may be desirable to modify the cart and move the LED to be more visible depending on your filming setup.