Signal sensing question

[millrl]

I reproduced the setup described in Mark's Signal Sensing Thread - using GPIO2 and a Y audio cable connected to one of the audio out adapters at the back of my TV.
With the TV off, HSlog consistently shows values such as: VAL= 4; MIN= 4; MAX= 4 . The values rarely vary by more than 1 unit.
With the TV on at relatively low volume, but still listenable levels, the values tend to run: VAL= 2-6 ; MIN= 0-3 ; MAX= 3-6
With the volume turned up (rather loud): VAL= 4-20 ; MIN= 0-3 ; MAX= 8-20.

Are the relatively high numbers with the TV turned off reasonable? I can't realistically differentiate between the off condition and on condition until the volume is turned up quite high. Would changing the "DELAY" or any other settings be of any help?

Thanks for that thread - it's a huge help getting started with the I/O capabilities of the BC4. On that note, I have a little project that I'd like some help with - but I'll start another thread for that.

[BitWise_Mark]

The values you described when the TV is off are pretty typical, the outputs often "float" slightly above 0 when a device is off. It's possible that the fact that you are using a Y-cable is influencing the values you are seeing. Are there any other un-used outputs on the TV you might put to use for signal sensing? For example, some TVs will have a coaxial digital output, or even an additional video output that can be used. You can even set the GPIO as a digital input in that case, and make things a little easier when evaluating the input.
When using the GPIO as an analog input, increasing the delay value can make sure that the MAX value is well differentiated from the MIN, but only to the extent of the signal present at the input.
All of that being said, it looks like you should still be able to work as you've got it now, if you increase the delay a bit. Since you know that the input floats around 4, you could make your evaluation: If MIN <=2 AND MAX >=5. From what you've described, those two statements should indicate an "on" state. An increased delay will help ensure that the MIN stays as low as possible and the MAX stays as high as possible, but you don't want to increase the delay too much. Just play a bit, and I think you'll be able to find a suitable setting.