PPM Encoder source location

Where is the source code currently located for ArduPPM and PPM Encoders?

https://ardupilot.org/copter/docs/common-ppm-encoder.html

points to https://github.com/ArduPilot/ardupilot/tree/master/Tools/ArduPPM

which prompts a 404.

Github says- We couldn’t find any repositories matching ‘org:ArduPilot PPM’

Our organization has distributed several robotics kits containing Futaba receivers which produce simultaneous channel pulses and I need to support students reading those pulses in Arduino based sumo robots.

The Arduinos must also contain code for additional tasks, so the .hex file is not sufficient.

Some of these sumo bots may use commercial PPM encoders, others may just integrate the PPM code. We greatly appreciate the work ArduPilot and its community has done for educational robotics.

You can find the PPM arduino sketches in older older branches/commits of the ardupilot codebase on github. Also, I would recommend using " BuzzsArduinoCode"

Thanks, but BuzzsArduinoCode uses pin change interrupts and seems to rely on sequential arrival of PWM pulses. I am supporting Futaba R2004GF receivers.
R2004GF (FHSS) - FutabaUSA
They begin PWM output on 2 channels simultaneously, then the other 2 channels also begin simultaneously. So the sequence of pulses do not come one at a time as expected, and interrupts are missed. The documentation DOWNLOADS: Advanced User Tools — Plane documentation says

ArduPPM_v2.3.16_ATMega328p

Changes:

– New interrupt system that handles certain Futaba receivers better (simultaneous changes on groups of R/C channels in fast intervals)

That is what I need. As you suggested

I just don’t know where they are. I have searched github, but they seem to be missing. Do you have a link?

Edit: Just figured out how to select other than the master branch on github and found ardupilot/Tools/ArduPPM at ArduPlane-release-AVR · ArduPilot/ardupilot · GitHub
Is that the latest version of ArduPPM?
I see it is similar to Buzzs so maybe I misunderstood and Buzzs will work. I’ll need to compile and try it out. I certainly like the simplicity of Buzzs code better.