@Wardbob, Welcome back. can you put a location or country on your profile so that things like suppliers can be more appropriatly cited for you.
I have been playing with a LED as a combined display and sensor very recently. Extending on the work of Wilf Ritger with his dark sensing circuit of 2007.
The circuit is simply changed to light sensing by XORing the LED anode with 0 instead of 1. So a bit of a no-brainer there. I assigned the result to a variable instead of directly to the pin and so was able to copy it to the pin and to report it to the screen monitor using sertxd. Most of my testing was in my living room in the evening so the lights were on and with a 5mm water clear green LED. Before I adapted the code, it also worked eminently with a 5mm coloured red LED package and a 3mm coloured yellow LED package.
My code changes are on a netbook, elsewhere at the moment, (I'm too idle to reach for it) so I will post them tomorrow, but to be going on with, here is Wilf's circuit and comments - take the nap time comments as out of date!
I found in the first nap that 2 became unstable, 3 was good and as I went towards a max of 7 the sensitivity dropped away significantly. 08M parts are max nap 7. 08M2 go out to 40 seconds, but I'm currently using a spare 08M. The second nap had the effect of extending the LED on time. With a maximum of 7, I changed this figure carefully as there was no current limiting resistor on the LED. I suspect that with an 08M2 that you could damage the LED, so take care.
I think that with an illuminating LED and sensor aided through glass, that a finger could reflect sufficient light to be used for switch selection. An audible feedback would give it a better performance curve I think. After the DO statement, add
sertxd (#b0, " ") and change pinC.2=pinC.2 xor 1 to
b0=pinC.2 xor 1 xor 0 for a light sensor. This will leave the LED as a sensor only, so adding the line
pinC.2=b0 will bring back flashing and of course untested but
pinC.2=not b0 will change the phase of the flashing but might turn out to be really useful or disterous and self defeating. I have yet to check out that option.
I'm sure that you get the idea and I'll report back as soon as I have made the tests tomorrow, Wednesday or Thursday at the latest. Watching the changes 0 to 1 in the monitor is instructive.
Have fun!
It also works with the AXE027 attached and the 10k/22k resistors connected. leaving pin3 /C.3 floating isn't an issue. So other than the basic download circuit all you need is your selected LED. The cathode has the shorter lead (until you clip it) and yes I had to check that, twice! The cathode is the anvil which will still be the same long after the leads have been clipped.