Audio Frequency Counter

[mister_e]

Hi, here's a simple code based on a PIC16F84A-20/P. Can be use as a audio frequency counter. It show the frequency on 3 x 7 segments display. It also place the decimal point.

have fun !

[mister_e]

And those who want also the schematic + code package, see this link to the Melabs Website. Choose Counter.zip

http://www.melabs.com/resources/samples.htm#submitted

[sanchit04421]

hi.
i m new here
i wanted t know if i could get a pic program code for frequency counter which can measure upto 1mhz.
is it available for download on net??
i need it urgent for my project! thanks

[charudatt]

Hello Steve,

I have run into some problem using your code for a 16F628A with a 16x2 LCD.

I am basically making a audio frequency counter, which would then be used to control a set of 8 LED's depending upon the Input frequency on PORTB.

Keeping this in mind I tried to output the frequency on the LCD but I get jumping figures at high speed. I believe , I have to introduce a delay between the display. Secondly , connecting 10K to ground on Pin#3 with 1K in series , as your circuit says, I don't get any reading. Which means , I need some impedence matching or may be a signal conditioner.

My audio source is from my desktop computer , audio out.

my code so far -

@   __CONFIG  _HS_OSC & _MCLRE_OFF  &  _LVP_OFF & _WDT_ON & _PWRTE_ON  & _BODEN_ON
DEFINE OSC 20

            ;76543210           
    TRISB = %00000000			
    TRISA = %11110000
 
DEFINE LCD_DREG PORTB 			'Define PIC port used for LCD Data lines
DEFINE LCD_DBIT 0 			    'Define first pin of portb connected to LCD DB4
DEFINE LCD_RSREG PORTB 			'Define PIC port used for RS line of LCD
DEFINE LCD_RSBIT 5 			    'Define Portb pin used for RS connection
DEFINE LCD_EREG PORTB 			'Define PIC prot used for E line of LCD
DEFINE LCD_EBIT 4 			    'Define PortB pin used for E connection
DEFINE LCD_BITS 4 			    'Define the 4 bit communication mode to LCD
DEFINE LCD_LINES 2 			    'Define using a 2 line LCD
'DEFINE LCD_COMMANDUS 2000 		'Define delay between sending LCD commands
'DEFINE LCD_DATAUS 50 			'Define delay time between data sent.

    
    ' Interrupt and register definition
    ' ---------------------------------
    '
    OPTION_REG = %1111000   ' TMR0 clock source : RA4/T0CKI
                            ' increment on low to high transition
                            ' Prescaler assign to WDT
                            ' WDT rate 1:1
                            '
    INTCON = %10100000      ' Enable global interrupt
                            ' Disable EE write interrupt
                            ' Enable TMR0 overflow interrupt
    CMCON = 7            ' disable analog comparator
    VRCON = 0            'turns off Vref for min current 

        
    ' Variable definition
    ' -------------------
    '
    DisplayPort  var PORTB   ' Port for 7 Segments     
    ClockInput   var PORTA.4 ' Input pin for signal
    _7Seg1       con 14      ' enable more significant 7 segment display
    _7Seg2       con 13      ' enable mid significant 7 segment display
    _7Seg3       con 11      ' enable less significant 7 segment display
    Digit_1	     var byte    ' Hundreds digit
    Digit_2	     var byte    ' Tenth digit
    Digit_3	     var byte    ' Unit digit
    ToBeDisplay	 var word    ' Result of count to be send to 7 segment display
    Display      var byte    ' Temp variable
    DisplayLoop  var byte    ' 
    Delay        var word    ' Variable for Delay loop
    OverFlowVar  var word	 '
    Thousands	 var bit	 ' Flag for count >= 1000 & < 10 000 
    TenThousands var bit	 ' Flag for count >= 10 000

    ' Variable and software initialisation
    ' ------------------------------------
    '
    tobedisplay = 0 ' set initial value of count
    TMR0 = 0        ' reset prescaller 
    on interrupt goto SetVarToBeDisplay
    
MainLoop:

    ' MainLoop
    ' ---------
    '
    ' 1. display the result of the count on RA4 pin
    ' 2. refresh display
    ' 3. reset Timer0 
    ' 4. reload prescaler.
    '
    ' Duration of the procedure : 1 sec 
    '           fine tuned by DelayBetweenEachDisplay Sub
    '
    ' Looping 1 sec and get results of the pulse count in
    ' TMR0 + OverFlowVar
    '
DisplayRefresh:
	'
    ' Testing amount of count
    ' -----------------------
    '
    ' Get the result of count and place decimal point flag
    ' on the according 7 segments
    '
    If tobedisplay>=1000 then
    	tobedisplay=tobedisplay/10
    	if tobedisplay>=1000 then
    		tobedisplay=tobedisplay/10
    		Thousands=0
    		TenThousands=1
    	else
    		TenThousands=0
    		thousands=1
    	endif
     else
    	thousands=0
    	tenthousands=0
    endif
    
    LCDOut $FE,$C0, "COUNT: ",DEC tobedisplay , "    " 
    gosub DelayBetweenEachDigit
    tobedisplay = OverFlowVar + TMR0
    OverFlowVar = 0 ' Reset OverFlowVar
    TMR0 = 0        ' reset prescaller

    goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh


DelayBetweenEachDigit:

    ' DelayBetweenEachDigit
    ' ---------------------
    ' Produce delay of about 3 mSec 
    '
    ' Fine tuned with MPLAB StopWatch to get MainLoop = 1 sec
    '
	for delay=1 to 307
	    @ nop
	next
	@ nop
	@ nop
	@ nop
	@ nop
	@ nop
	@ nop
	@ nop
    return


    disable
SetVarToBeDisplay:
    '
    ' SetVarToBeDisplay
    ' -----------------
    ' interrupt routine of TMR0 overflow
    '
    ' Reset prescaller
    ' Reset overflow flag
    '
    OverFlowVar = OverFlowVar + 256 
    INTCON.2 = 0 ' clear overflow flag
    TMR0 = 0     ' reload TMR0
    resume
enable

[Archangel]

but I get jumping figures at high speed.

Hi charudatt,
Here is an Idea to help with the jitters, after the LCDOUT, save tobedisplay var to a dummy var, and then before updating the display check to see if tobedisplay = dummy and if it does, go back to the loop until it changes.
Also, what's that about?

goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh
    goto DisplayRefresh

[charudatt]

I thought I got my bearing all messed up. My project is basically a Sound to Light idea (Disco light), and I thought , it was done by sampling the frequency and hence , I went about trying a Audio frequency meter.

There was a error in the code, I wanted to introduce a slight delay in the LCD routine and i put in those lines to goto DisplayRefresh, actually it should have been Gosub DisplayRefresh.

Anyway, any pointer / idea for disco lights using PIC.

Thanks all.

regards

[Archangel]

I built one (actually several) back around 1971 in high school electric shop, used an audio transformer secondary to speaker and primary to the gates of 3 SCRs through 3 R/C filters for 3 channel outputs to control 3 strings of colored lights put behind diffuser panels made for fluorescent lights. Wow shades, some Metal music, some get high, and who could even think of going to war ?
Back on topic . . . R/C network, Analog voltage detection, digital output . . . same theory should work.

[charudatt]

OK , did you mean this http://4.bp.blogspot.com/_BQac7gcHPK...1600/color.gif

Anyway , I got a lot of dope on this forum relating to this topic and shall give it a try.

Thank you for the help.

regards

[Archangel]

OK , did you mean this http://4.bp.blogspot.com/_BQac7gcHPK...1600/color.gif

Anyway , I got a lot of dope on this forum relating to this topic and shall give it a try.

Thank you for the help.

regards

http://4.bp.blogspot.com/_BQac7gcHPK...P-keI3U/s1600/
Yes, that was it.