Glossary

ADU  -  Analog to digital converter unit.  The CCD signal as represented in terms of the bits at the output of the analog to digital converter; 1 ADU = 1 ADC least significant bit.  The camera transfer constant provides the conversion factor from ADU to photoelectrons.   For the main Pyxis camera, this conversion factor is close to 1.7 electrons/ADU.
CCD  -  Charge coupled device imaging sensor.
MCU  -  Microcontroller
PSF  -  Point spread function. The image of a point source, in this context, on the CCD detector. 
USB  -  Universal serial bus.