This is v2 of the lap timer written a while ago.
with EasyRaceLapTimer and OpenLap adopting a common protocol this now supports the same protocol and allows to add more.

Arduino is used to handle the interrupts and time the laps.
Raspberry Pi (one, zero, 2, 3) for hosting the website.

arduino (nano) connects to the usb port on the raspberry Pi.

a wifi dongle with setup to make the Pi an Access Point is required

Arduino multiple IR receivers is possible due to https://github.com/etix/Arduino-IRremote