www.micro-examples.com : PicoBat

PicoBat running on a bread board

An ultrasonic bat detector with only 3 components !

PicoBat : a PIC-based simple and cheap ultrasonic detector

A short video clip is sometimes better than a long explanation :

The idea of this circuit is to hack the PIC oscillator circuit, by replacing the crystal by a piezo sensor : the frequency of the oscillator then depends on ultrasounds.

Oscillator frequency is then divided by 4 by the PIC, and pushed into a piezo speaker.

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

Circuit Schematic

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

C Source code

/*
 *******************************************************************************
 * picoBAT : an ultra simple ultrasonic bat detector
 *******************************************************************************
 *
 * Author : Bruno Gavand, February 2009
 * see more details on http://www.micro-examples.com/
 *
 * source code for mikro C compiler V8.2
 * feel free to use this code at your own risks
 *
 * target : PIC12
 *
 * PIC PIN Assignemnt :
 *
 * GP0 GP1 : piezo speaker
 * GP5 : ultrasonic transducer receiver
 *
 *******************************************************************************
 */

void    main()
        {
        /*
         * configure GPIO as digital port
         */
        CMCON0 = 7 ;
        ANSEL = 0 ;

        TRISIO = 0 ;
        GPIO = 0b01 ;

        for(;;)
                {
                /*
                 * toggles speaker outputs
                 */
                GPIO ^= 0b11 ;
                }
        }

No, there is no mistake, full source code is above !

Download project

Download PicoBat-project.zip file for mikroC : File:PicoBat-project.zip

Includes :

• mikroC PRO project files for PIC12F683, should work also with most of PIC
• picoBat C source code
• picoBat .HEX files

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