IR Remote Decoder

The Stellaris/TivaC board packs decent computational power for embedded application but does not offer enough input (only two simple push buttons) for many applications. Beside sparinig out many I/O pins and a lot of wiring effort, this problem can be solved using IR remote. Many home entertainment devices come with a remote with decent quality and design. It is entirely possible that you have some old remote lying around after retirement of VCRs, VCDs, tube TVs. If not, a universal remote only sales for a few bucks these days. Together with a cheap IR receiver chip (less than $1), the IR remote effectively works as a fancy wireless controller for any project you made with Stellaris/TivaC.

I have bought the IR receiver chip VS1838 (demodulate 38KHz) for this project. You can get it for as low as $2.5/5 pcs with free shipping. I have connected the chip to on board power and the output pin of the chip to PF4.

Here is the overall Simulink diagram. It is divided into several sub systems according to functionality.

The decoding process is mostly done using Stateflow. Four popular IR remote protocols are covered: NEC, RC-5, SONY and RCA, which should be able to cover most IR remote controller in the market. In case a modification is necessary to fit your own device, three bit coding formats are also covered. NEC and RCA uses pulse distance coding, SONY uses  pulse width coding and RC-5 use bi-phase coding (Manchester coding).

After the decoding process, information about the key pressed is feed into Debug Print block to for display in a terminal on the PC side (see pic below). This demo can be embedded into a bigger project. The decoded information can be directly used to control other devices that connect to the TivaC board.

This demo project can be found in the Stellaris/TivaC Hardware Support Package (see installation instruction here). If you do not want to download the support package, you may download this file to view the Simulink diagrams and the note I have wrote. Notice, without the support package, it is not possible to download the demo to TivaC and some blocks in the diagram may appear to be missing.

In order to demonstrate how this demo can be used in application, I have built a simple Simulink diagram that uses IR remote to control a R/C servo.