AO-SPK

From Curuxa

Electronic circuit

Schematic

Bill of materials:

1x Low power speaker, usually piezoelectric
1x 1kΩ 1/4W resistor
3x Straight female headers (usually sold as 40-pin strips)
Some thin wire
Some heat shrink tubing

As any other speaker, it will sound when a variable current flows through it.

Avoid supplying constant voltages to the speaker.

The simplest way to generate sounds is by setting an output digital pin on the microcontroller as 1 and 0 repeatedly, that would generate a square wave.

Wiring

Printable version: Single, Quad

Construction

Test

The following code can be compiled using SDCC.

MBP8, delays

/*==================================================================
* Sample program for AO-SPK using an MBP8
*
* Plug AO-SPK to GP5 (pin 2).
*
* http://curuxa.org
*=================================================================*/
 
#define OSC_8MHz
 
#include <MBP8.h>
#include <Delays.h>
 
ConfigBits(_CPD_OFF & _CP_OFF & _BOD_OFF  & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTOSCIO);
 
#define Spk GP5
 
void Setup() {
	AdcDisable();
	SetDigitalOutput(5);
	SetIntosc8MHz();
}
 
 
void main() {
	Setup();
 
	while(1) {
		Spk=!Spk;
		Delay(1);
	}
}

MBP8, Timer0

/*==================================================================
* Sample program for AO-SPK using MBP8 Timer0
*
* Plug AO-SPK to GP5 (pin 2).
*
* http://curuxa.org
*=================================================================*/
 
#include <MBP8.h>
 
ConfigBits(_CPD_OFF & _CP_OFF & _BOD_OFF  & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTOSCIO);
 
#define Spk GP5
 
Interrupt {
	Spk=!Spk;
	TMR0=114;
	T0IF=0;
}
 
void Setup() {
	AdcDisable();
	SetDigitalOutput(5);
 
	//setup timer
	//PIC12F683 runs by default at 4MHz
	//Fosc=4MHz, Tosc=250ns, Tcy=1us
	//for a 440Hz tone whe need a 880Hz timer frequency. That's 1136 instructions per cycle
	//...1:8 prescaler (PS=0b010). 142 TMR0 counts  per cycle. preload=114	
	PSA=0; //assign prescaler to Timer0
	T0CS=0; //clock source=internal oscillator
	PS2=0; //prescaler... 	PS1=1;
	PS0=0;
	T0IF=0;
	GIE=1; //enable global interrupts
	T0IE=1; //enable TMR0 interrupt
}
 
 
void main() {
	Setup();
 
	while(1) {
		//do nothing
	}
}

MBP18, delays

/*==================================================================
* Sample program for AO-SPK using an MBP18
*
* Plug AO-SPK to RA1 (pin 18).
*
* http://curuxa.org
*=================================================================*/
 
#define OSC_8MHz
 
#include <MBP18.h>
#include <Delays.h>
 
ConfigBits1(_CP_OFF & _DEBUG_OFF & _WRT_PROTECT_OFF & _CPD_OFF & _LVP_OFF & _BODEN_OFF & _MCLR_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_IO);
 
#define Spk RA1
 
void Setup(){
	//set all pins as digital, instead of analog inputs
	ANSEL=0;
 
	//set RA1 as a digital output
	TRISA1=DigitalOutput;
 
	SetIntosc8MHz();
}
 
void main(){
	Setup();
 
	while(1){
		Spk=!Spk;
		Delay(1);
	}
}

AO-SPK - Curuxa