Analog Input and Sleep Mode

Project Description

This design allows for an analog signal to be sampled and the amplitude output to the screen. The design features a power saving sleep mode that conseves power when not in use.

Materials used:

Design Overview

The analog signal comes from a signal generator which is run through a noise reducing circuit. This circuit was constructed using an extra board which had to be built to act as a "docking station" for the 16C71. Not only was it needed for noise reduction, but it also allows the A/D converter to be connected to an outside sorce rather than the potentiometer on the demo board. This needed to be built since the PicDemo board is a demonstration board and not a development board.

This outside circuit is run through the built in A/D converter on the 16C71, and output to the leds on the board. If a key is hit the A/D is sampled and the result shown to the screen, otherwise the circuit is put into its powersaver mode.

One of the limiting factors for this design is the speed of the A/D converter. Since it can only do one conversion about every 20uS, it severely limits the frequency of the input signal. A chip with a faster A/D might serve better for this reason.

Manufacturability

The sleep mode makes this product more efficient. When the A/D is turned on the chip needs about 15uA, and with it off about 20mA. This is a considerable savings.

Created by:

Fred Strelzoff
and
Bernard Celli
(www-unix.oit.umass.edu/~ber nard