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Date Posted: January 12, 2010

Introduction

This project serves two purposes. First is to be just a simple IR receiver for Sony remote controls. I used an old Sony RM-D190 remote control from an old CD player I threw out long ago to test. I think newer Sony SIRC remotes are 12 bit, but this one is only 11 bit, so if anyone wants to use this code as a remote control receiver they will have to change it to 12 bit, which should be quite simple. When the receiver gets data over the IR, it sends it as 2 bytes over RS232 to a computer. The data will be (in 11 bit mode) from MSb to LSb: 5 bits of 0, 3 bits of device, 8 bits of data packet. Or something like that. The second part of the project is to make an IR emitter transmit data when it receives information over the RS232 line.

Update January 12, 2010: I think this remote really might be 12 bit and the last bit pretty much served as a stop bit. My remote worked with the receiver firmware perfectly, but my sending firmware did not which I finally realized was due to the last half of the last bit (when the signal is turned off) lasting more than 0.6ms. It never failed on the Sony remote which leads me to believe the Sony remote has some extra bit at the end.

I got most of my info on Sony SIRC from this page: http://www.sbprojects.com/knowledge/ir/sirc.htm.

The schematic below is incomplete. I left out the RS232 part cause I'm feeling lazy. Should be straight forward. I'll add it in eventually. One thing to note, instead of using DS275's on this project, I used the dreaded MAX232. ZOMG!

Pictures

	Here is a prototype circuit sitting next to the remote control I've been using to test with. I used a Spark Fun UART to RS232 converter here just to make the circuit simpler.
	Here is an example of what the output of the chip looks like. This crappy 486 laptop is running Procomm Plus in FreeDOS and is hooked up to the circuit. When I push buttons on the remote, they are printed as hex chars (for debugging). The # marks indicated IR errors.
	Here is the final two circuits. Using terminal programs (Picocom on Linux and Procomm Plus on FreeDOS) I can communicate between the two computers with 2 way communication over IR using these circuits.

Schematic

Source code
ir_comm.asm

Copyright 1997-2010 - Michael Kohn

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