Help with infrared signals

[Don't_look_Im_hideous]

Hello! I would like to write a python script for my raspberry pi to allow it to send ir signals, a bit like a universal remote (Yes I know I could use something prepackaged, but I'll learn more this way). I can code in python pretty well and have the hardware for the project, but I think I should know more about the protocols for ir transmission before I write any code. I know the basics, it's coded into binary with the pulses/gaps for the "ones" and "zeros" being set by the protocol. There's also a "header" which is sent first. But that's roughly all I know. I would like my program to be able to read the remote profiles from lirc, here's an example. Is there a guide online somewhere that can tell me what all the jargon in there means?

Thanks

Matthew

 

[KeepItSimpleStupid]

It will be instructive to look here: https://techdocs.altium.com/display/FPGA/NEC+Infrared+Transmission+Protocol which briefly describes the NEC protocol. Unfortunately, there are lots of others. NEC is pretty well thought out. There is some amount of error checking and you can have multiple devices of the same type. The first burst allows the receiver to adjust the gain.

Your gating or enabling the carrier signal. It's not the signal that your sending. It would, however be the recovered signal from an IR reciever module from Vishay. It might be inverted, not sure.

By no means are all IR signals like the NEC protocol. The carrier frequency can be up to nearly 100 kHz.

 

[Nigel Goodwin]

While the carrier 'can' be higher, almost all are around 36/38KHz - the only 100KHz I know of was old B&O remotes, which was why One For All remotes couldn't work them.

While NEC is very popular, the most common is Philips RC5/RC6, because Philips are also a component supplier, and sell their remote control chips to vast numbers of other manufacturers. This does cause a number of issues though, with other manufacturers using the wrong code ID's (such as TV remote codes on an audio system).

Probably the simplest is the Sony SIRC system, and this is covered in my PIC tutorials.



You might consider checking the Arduino libraries, as there are a number of IR remote examples for Arduino, which you could study and replicate for PI. The NEC protocol is very popular with Arduino, simply because the cheap Chinese remotes that come in PI kits are NEC based.

Or if you google, there are a number of hits for PI, such as this one.

https://shallowsky.com/blog/hardware/raspberry-pi-ir-remote.html

 

[dr pepper]

I've used remotes for a few projects, I have a program from github I think that runs on an arduino, and it tells you what standard a remote is just by using a remote sensor and pointing the remote at it, this way I can use fairly well any remote I like.
Not sure whats around for the pi, you might be able to port arduino to it, there might even be a arduino emulator.
Philps and nec are common.