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| | Tip: Instead of connecting your output speaker with one pin to VDD/VSS, more output can be generated by connecting with two output pins and swapping them. This trick seems to work, and I think it works because a speaker is current-driven. For a piezo, it doesn't matter, since a piezo is voltage-driven. | | Tip: Instead of connecting your output speaker with one pin to VDD/VSS, more output can be generated by connecting with two output pins and swapping them. This trick seems to work, and I think it works because a speaker is current-driven. For a piezo, it doesn't matter, since a piezo is voltage-driven. |
| − |
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| − | Cricket sample code:
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| − |
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| − | ----
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| − | <p><code>
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| − | ; File cricket.asm
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| − | ; Assembly code for a 4MHz PIC12F509 microcontroller
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| − | ;
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| − | ; Description: Fake cricket sound for a 12F509
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| − | ; Author: Vincent
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| − | ; Last Modified: 17 / 8 / 06
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| − |
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| − | ;
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| − | ; CPU configuration
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| − | processor 12f509
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| − | __config _IntRC_OSC & _WDT_OFF & _MCLRE_OFF
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| − |
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| − | ;=======================================
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| − | ; Configuration (FUSE) BIT Definitions
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| − | ;=======================================
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| − | _MCLRE_ON EQU 0FFFh
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| − | _MCLRE_OFF EQU 0FEFh
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| − | _CP_ON EQU 0FF7h
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| − | _CP_OFF EQU 0FFFh
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| − | _WDT_ON EQU 0FFFh
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| − | _WDT_OFF EQU 0FFBh
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| − | _LP_OSC EQU 0FFCh
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| − | _XT_OSC EQU 0FFDh
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| − | _IntRC_OSC EQU 0FFEh
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| − | _ExtRC_OSC EQU 0FFFh
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| − |
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| − |
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| − | ; 509 defs
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| − |
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| − | PCL equ H'02'
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| − | STATUS equ H'03'
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| − | OSCCAL equ H'05'
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| − | GPIO equ H'06'
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| − | Z equ H'02'
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| − |
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| − | ; variables
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| − |
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| − | CounterA equ H'1F' ; delay counter
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| − | CounterB equ H'1E' ; delay counter
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| − | CounterC equ H'1D' ; delay counter
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| − | CounterD equ H'1C' ; delay counter
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| − |
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| − | ; statics
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| − |
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| − | aupin equ H'00'
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| − | aupin2 equ H'01'
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| − |
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| − | ; Program
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| − |
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| − | org 0 ; start at address 0
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| − |
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| − | start:
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| − | movwf OSCCAL ; calibration bits
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| − | movlw 0 ; set tris read except for aupin
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| − | tris GPIO
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| − |
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| − | mainloop:
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| − |
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| − | call freq4500
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| − | call freq4200
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| − | call freq4500
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| − | call freq4200
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| − | call freq4500
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| − | call freq4200
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| − | call freq4500
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| − | call freq4200
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| − |
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| − | none:
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| − | call secdelay
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| − |
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| − | goto mainloop
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| − |
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| − | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| − | ; subs
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| − |
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| − | freq4200: ; freq loop should be 238 cycles to get 4200Hz
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| − | movlw 0040h ; counter set for 11msec
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| − | movwf CounterD
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| − |
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| − | loop42:
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| − | bcf GPIO,aupin
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| − | bsf GPIO,aupin2
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| − | call del42
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| − | bcf GPIO,aupin2
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| − | bsf GPIO,aupin
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| − | call del42
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| − |
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| − | decfsz CounterD,1
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| − | goto loop42
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| − |
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| − | retlw 0
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| − |
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| − | freq4500: ; freq loop should be 222 cycles to get 4500Hz
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| − | movlw 002Dh ; counter set for 14msec
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| − | movwf CounterD
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| − | loop45:
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| − | bcf GPIO,aupin
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| − | bsf GPIO,aupin2
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| − | call del45
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| − | bcf GPIO,aupin2
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| − | bsf GPIO,aupin
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| − | call del45
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| − |
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| − | decfsz CounterD,1
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| − | goto loop45
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| − |
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| − | retlw 0
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| − |
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| − | ;;;;;;;;;;
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| − | del42
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| − | movlw 0023h
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| − | movwf CounterA
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| − |
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| − | loop4 decfsz CounterA,1
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| − | goto loop4
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| − |
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| − | retlw 0
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| − |
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| − | ;;;;;;;;;;;
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| − | del45
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| − | movlw 0026h
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| − | movwf CounterA
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| − |
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| − | loop5 decfsz CounterA,1
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| − | goto loop5
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| − |
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| − | retlw 0
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| − |
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| − |
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| − | secdelay
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| − | ; insert picloops code here
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| − | ;PIC Time Delay = 8,0000040 s with Osc = 4,000000 MHz
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| − | movlw D'41'
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| − | movwf CounterC
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| − | movlw D'190'
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| − | movwf CounterB
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| − | movlw D'87'
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| − | movwf CounterA
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| − | sloop decfsz CounterA,1
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| − | goto sloop
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| − | decfsz CounterB,1
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| − | goto sloop
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| − | decfsz CounterC,1
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| − | goto sloop
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| − | retlw 0
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| − |
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| − |
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| − | end
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| − |
| |
| − | </code></p>
| |
Revision as of 22:19, 27 August 2006
A fake cricket is not a really useful application, but it is very simple to create and can be fun to drive people crazy. Or to hide and seek with children.
If you use a high-impedance speaker, it can be driven directly from the output pins of your microcontroller. A piezo element should also work, but might not give much output power with low voltages.
For a low-impedance speaker a simple 'amplifier' (transistor) should work.
Tip: Instead of connecting your output speaker with one pin to VDD/VSS, more output can be generated by connecting with two output pins and swapping them. This trick seems to work, and I think it works because a speaker is current-driven. For a piezo, it doesn't matter, since a piezo is voltage-driven.