IR Widget Consumer infrared remote control capture and visualization


Posted on Feb 5, 2014

The IR Widget operates in a way that makes it compatible with modern multitasking operating systems. It is able to determine the carrier frequency and demodulate the carrier in the digital or analog domain. The captured information can be used to view, recognize or reproduce the signal. The


IR Widget Consumer infrared remote control capture and visualization
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hardware is designed to be as simple and low cost as possible. A PIC12F629 was used for development, but almost any PIC that uses the 12 or 14 bit instruction set could be used. The usual approach to low cost IR capture typically consists of an IR detector or demodulator module connected to a serial or parallel port. This can work quite well when the CPU is dedicated to servicing the port. It often performs poorly within a preemptive multitasking operating system. The OS is constantly servicing hardware interrupts even when the system is idle, so the IR capture is constantly interrupted. Disabling hardware interrupt handling is dangerous and may be prohibited by the OS. CPU usage is high when polling is used. Using the hardware interrupt capability of the port can greatly reduce CPU load, but interrupt latency may cause inaccurate results. Boosting thread priority may help, but results vary. Parallel and serial ports are becoming less common, and USB adapters do not work for these simple circuits. There are many DIY and commercial products that use a microcontroller to process the IR signal. These are typically intended for remote control rather than research. Many of them have only an IR demodulator, so they can not determine the carrier frequency or report precise timing. The data sent to the host computer may be in a format that does not allow reconstruction of the actual literal IR signal. The acquisition duration is...




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