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I have a laptop computer that runs a program and when it finishes running, it plays a WAV sound file (which I can preselect) to tell me that it has finished. Sometimes I am not around to hear the sound so I would like to have a LED light turn on to show that it has finished running.
One solution is to have some kind of software installed on the computer to do this but I prefer to have NO software installed on that computer for various reasons. I want a hardware solution that does not require any software drivers outside of what the Windows operating system provides.
For example, my first attempt was to use a USB stick and put my WAV file on the USB stick. When the program ends, it reads the WAV file from the USB stick hence causing the LED on the USB stick to flash. Then all I have to do is build a simple latch circuit to keep the LED turned on.
The problem with this approach was that once the operating system read the WAV file, it kept the WAV file in its internal cache, henceforth, it no longer goes to the USB stick to read the WAV file. I found no way to turn off READ caching on a USB stick, only possibility was turning off Write Caching.
I also thought about making this USB drive a network shared drive to somehow force the operating system to re-read the file but I didn't get too far because I don't know enough.
To recap, I am looking for a hardware solution to turn on a LED when a certain preselected WAV file is played, and it should:
- involve no software other than what Windows come with
- need to leave the speaker operational as normal speaker which means you should not alter the use of the speaker just for this purpose nor should you count on the volume setting being set at certain level (it should work even if sound is muted), also there is no line output signal on this laptop
I don't mind spending some money on hardware development and/or modification because I can think of many uses for this but the actual hardware material costs has to be low (