Digital LED Pixels: Instructions for use and a characterization of their properties.
This article details how to control light emitting diodes (LEDs) using an ordinary desktop computer. By combining digitally addressable LEDs with an off-the-shelf microcontroller (Arduino), multiple LEDs can be controlled independently and with a high degree of temporal, chromatic, and luminance precision. The proposed solution is safe (can be powered by a 5-V battery), tested (has been used in published research), inexpensive (∼ $60 + $2 per LED), highly interoperable (can be controlled by any type of computer/operating system via a USB or Bluetooth connection), requires no prior knowledge of electrical engineering (components simply require plugging together), and uses widely available components for which established help forums already exist. Matlab code is provided, including a 'minimal working example' of use suitable for use by beginners. Properties of the recommended LEDs are also characterized, including their response time, luminance profile, and color gamut. Based on these, it is shown that the LEDs are highly stable in terms of both luminance and chromaticity, and do not suffer from issues of warm-up, chromatic shift, and slow response times associated with traditional CRT and LCD monitor technology.
Institute of Ophthalmology, University College London (UCL), 11-43 Bath Street, London, EC1V 9EL, UK. p.r.jones@ucl.ac.uk.
Pete R
PR
Jones
Institute of Ophthalmology, University College London (UCL), 11-43 Bath Street, London, EC1V 9EL, UK.
Sara E
SE
Garcia
Institute of Ophthalmology, University College London (UCL), 11-43 Bath Street, London, EC1V 9EL, UK.|Department of Psychology, Durham University, Durham, UK.
Marko
M
Nardini
D008029:Lighting / Q000295:instrumentation*; D008838:Microcomputers; D010775:Photic Stimulation / Q000379:methods*; D012984:Software
Arduino; Color gamut; Light emitting diode; Luminance; Timing