The PIC16F690 microcontroller is one of Microchip midrange 8-bit microcontroller that has a build in 10-bit resolution of Analog to Digital Converter (ADC) peripheral. The ADC is one of the important features that enable us to digitize our analog world. Usually we use the electronic sensor to convert the analog value to the voltage level value. Some of the basic sensor such as LDR (Light Dependent Resistor) is used for measuring the light intensity or NTC (Negative Temperature Coefficient) a special resistor for measuring the temperature.
PIC Analog to Digital Converter C Programming – [Link]