I don't know how much current the link port can safely source, so using it to sink current when driving the IR LED might not be exactly safe. It works fine for me but my 5V source is from a regulated 9V PP3, which delivers a very low maximum current anyway.
It might be a good idea to build a small transistor power amplifier so that you only sink a very small current through the link port.
SonyIR is a library that can be used to send and receive commands using the Sony infrared controller (SIRCS) protocol.
Libraries are rather dull on their own, so I've also thrown together a program (likewise called SonyIR) that can be used to turn your calculator into a programmable remote control.
You can download the latest version or download a video (controlling a Sony TV - 960KB WMV).
- Send and receive data using the SIRCS protocol to control Sony devices via infrared.
- Support for 12-, 15- and 20-bit command words.
- Minimal hardware required (cheap single IR LED and optional resistor, depending on circuit) thanks to software modulation.
- Easily send single commands or repeated commands spaced at 45mS.
- Simple hardware thanks to cheap single-package IR module.
- Routine returns button code, device ID and number of bits (or an error condition).