PicoBat

A PIC-based simple and cheap ultrasonic detector.

Overview

An ultrasonic bat detector with only 3 components! The idea is to hack the PIC oscillator circuit by replacing the crystal with a piezo sensor: the frequency of the oscillator then depends on ultrasounds. Oscillator frequency is divided by 4 by the PIC and pushed into a piezo speaker.

It shares the same idea as PicoDetector, the metal detector.

Circuit Schematic

PicoBat circuit schematic

• The ultrasonic piezo receiver replaces resistor in PIC oscillator circuit.
• SP1 is any piezo speaker.

C Source Code

/*
 * picoBAT : an ultra simple and cheap ultrasonic detector
 * Author : Bruno Gavand, february 2009
 * http://www.micro-examples.com/
 * source code for mikroC compiler V8.2
 * target : PIC12, oscillator in HS mode
 * GP0 : speaker +
 * GP1 : speaker -
 */
void main()
    {
    CMCON0 = 7;
    ANSEL = 0;
    TRISIO = 0;
    GPIO = 0;
    for(;;)
        {
        GPIO ^= 0b11;
        }
    }

Download project