A Hewlett Packard Infrared Signal Decoder
Martin Hepperle
June 2015
Several Hewlett Packard pocket calculators are able
to send printer output via Infra-Red (IR) signals to
a small portable printer. They use an HP-specific
transmission protocol which is also called “Red
Eye”. This protocol is different from the bette
r known IrDA protocol. This document gives a brief
overview of the format and describes hard- and softwa
re to build a decoder system for this protocol.
This system allows receiving the “Red Eye” signals
with a computer via a serial or an USB interface.