Something is probably off in the wiring and I haven't used it in long enough that I don't know if the wiring is off. The current wiring was something I had written in a old notebook on about 8/4/15.

Notes from reading the TSL1406 datasheet

• Supply Voltage Min 3V Max 5.5V. Currently being powerd by 3.3V from the Photon 3.3V pin
• 3.3V logic should work fine for the controlling pins hold and clock
• Clock Frequency 5-8000kHz. Not sure what this is yet but perhaps the photon code that sends the analog reading in between every pixel is too slow to meet this requirement?
• V_out Typically 2V for White, 0.1 V for black pixels

Sigh

Wiring looks right and I tried playing with the exposure timing and delays in between Clock pulses. Data became all white and I couldn't figure out how to make the analog readings low.

It's tough without an oscilloscope to probe the signals that I would normally borrow from Ryan.

I think I will take a step back and start smaller using the same pins but using a potentiometer to mimic the analog readings so the circuit is simpler and I can check values by hand.