Day 16 (23rd May 2011)

A summing amplifier was used with +5V as one input and -30V as another input with weights in approximately 1:6 ratio. Thus a 30V output of the power supply gave 0.45V and 0V output of the power supply gave 4.33 V. These values were given to the analog input pins and a value between 81 and 892 was obtained. Appropriate mapping was used. In The calibrate function the duty cycles corresponding for one third, two third and the max value were stored in EEPROM. For inputs in different ranges, appropriate mapping was used to achieve multi-point calibration.