Going IR-less

A project log for RC5 Madness

Controlling an old Philips Amplifier with IR, RC5 and Home Assistant via esphome

schlionschlion 10/20/2023 at 17:580 Comments

I can now:

I had noticed RCA/chinch ports labeled SYSTEM CONTROL RC-5 on the back.

Apparently the receiver could and would send the RC-5 messages it received vie IR to other devices also I read about the possibility of connecting an additional IR receiver.

To check it out, I hooked up my "Oscilloscope" (DSO 150 shell). Once I figured out the triggers, I saw this, when sending IR commands in from the front:

Excellent, a 5V signal. My cheap logic analyzer can work with 5V. So I connected that next, called up pulse view and found the following:

Very nice, it's the demodulated packet that we sent in from the front. Interestingly, I could only see this on the top port. And for every address + command, I put in, I got a corresponding packet on the analyzer, even if the command didn't actually do anything. But that makes sense.

Only one thing was weird. I could see the commands, but even the ones that should be working, didn't work anymore. What's happening? I got very confused and checked my code if I had changed anything. After some time, I had the idea to bridge/connect both RC-5 Ports. It turns out, the bottom one is input and the top one output. And if the receiver notices something listening on the RC-5 output, it won't use those command anymore, but rather will wait for them to come back via the bottom port. At least that's my guess.

This of course means it might be possibly to forgo IR altogether and send the codes directly via wire. Exciting! And much cleaner, than having some IR LED in front of my newish shiny receiver. To test this, I hard-coded one command on an Arduino with half intervals of 889ns, and it worked 🎉

(see manchester_easy.ino in project files)

A wired-up Arduino sending a hard-coded transmission

It's possible to send commands by wire ✅