Multiplexing Four 7-Segment With Keypad And 4 Chanel ADC

Hardware Multiplexing Four 7-Segment With Keypad And 4 Chanel ADC

This section essentially incorporates the previous three sections to give a complete four channel voltmeter. Figure  shows a typical configuration. The analog channels are connected through individual potentiometers to their respective analog inputs and are sampled every 20 ms in a round robin fashion. The sampling rate can be increased to as fast as once every 5 us if required. The keypad sampling need not be any faster than once every 20 us.

Software for Multiplexing Four 7-Segment With Keypad And 4 Chanel ADC

The program samples the analog inputs and saves the result in four consecutive locations starting at “ADVALUE”, with Channel0 saved at the first location and so on. The four A/D channels on the PIC16C71 can be multiplexed with digital I/O, thus reducing overall pin counts and improving I/O pin usage in an analog application.

Multiplexing Four 7-Segment With Keypad And 4 Chanel ADC

Multiplexing Four 7-Segment With Keypad And 4 Chanel ADC Schematic Circuit