**********************
ambLight_pi.py    *
**********************
reads a photoCell
**********************
A photo-cell can be used to measaure the analog value of ambient light, but it can
also be used as a binary (digital) value of light/dark.  Total darkness occurs when
the photo-cell is covered (e.g. by a finger).  This light/dark situation is similar to a push-button 
which is what digLight returns as a binary value.  Because the Raspberry Pi cannot read
analog values,  an external ADC device is necessary (e.g. WeatherHap Pro, Pico, Seeed PN
03030279  that uses a ti ADS1115.)   The related digital routine digLight can be used
to measure light/dark as a binary value without need for an ADC.
Also for Seeed ADS1115 Raspberry Pi board (AIN0,AIN1,AIN2,AIN3).
/ambLight.txt
