Measuring audio phase shift through a circuit with a PIC

[HankMcSpank]

Hi Hank

Since you're stuck, I wonder if you could post/PM your code of now so that I can take a whack at it. I'll see if I can find your problem with the min value of comp2 value.

The barest minimum code which will compile and show the problem is sufficient. I should be able to run it.

Regards

Many thanks Jerson.

The latest version of code was part of a hulking long program, but I found an earlier variant, which is purely deals with the comparator interrupt timer1 counting & therefore makes it a lot easier to look at...

@ __CONFIG _FCMEN_OFF & _HS_OSC & _WDT_OFF & _MCLRE_OFF & _CP_OFF & _IESO_OFF & _BOR_OFF & _PWRTE_OFF

DEFINE  OSC 20          ' set Oscillator at 20Mhz.
DEFINE  NO_CLRWDT 1   ' PBP doesn't clear WDT automatically
DEFINE HSER_TXSTA 24h ' Enable transmit
DEFINE HSER_SPBRG 129 ' set USART to 9600 baud  @20Mhz

'*********************************************************************************
'16F690 Pin Connections....
' PIN# NAME     USE & CONNECTION
                '  1   Vdd      +5VDC power supply
TRISC.4 = 0     '  6   RC4      C2OUT
TRISC.3 = 1     '  7   RC3      C12IN3- (comparator1 input)
TRISC.2 = 1     '  14  RC2      C12IN2- (comparator2 input)
TRISA.2 = 0     '  17  RA2      C1OUT
                '  20  Vss      Ground
'*********************************************************************************
OSCCON.0 = %0001000 
txsta = %10100100   'setup the tx register
RCSTA.7 = 1         ' Enable RB7 for TX USART
INTCON.0 = 0        ' clears the RABIF Flag (to 0), COULD be 1 on reset (unique to F690)
ANSEL      = 0      'disable AtoD.
ANSELH     = 0      'disable AtoD.

'Turn on & Set up Comparator 1
CM1CON0.7 = 1       'Comparator 1 on.
CM1CON0.6 = 0       'C1OUT POLARITY BIT
CM1CON0.5 = 1       '1 = C1OUT is present on the C1OUT pin (pin 17)
CM1CON0.4 = 1       'C1OUT logic - 0 is not inverted  (1 for inverted)
CM1CON0.3 = 0       'unimplemented
CM1CON0.2 = 1       'Connect internally to the output of C1VREF   (or 0 for the the associated comp 'in' ext pin)
CM1CON0.1 = 1       'this bit with bit 1 set the external incoming pin - in this case c12in3- (pin 7)
CM1CON0.0 = 1       'this bit with bit 1 set the external incoming pin - in this case c12in3- (pin 7)

'Turn on & Set up Comparator 2
CM2CON0.7 = 1       'Comparator 2 on.
CM2CON0.6 = 0       'C1OUT POLARITY BIT
CM2CON0.5 = 1       '1 = C2OUT is present on the C2OUT pin (pin 6)
CM2CON0.4 = 1       'C1OUT logic is not inverted  (1 for inverted)
CM2CON0.3 = 0       'unimplemented
CM2CON0.2 = 1       'Connect internally to the output of C1VREF (or 0 for the the associated comp 'in' ext pin)
CM2CON0.1 = 1       'this bit with bit 1 set the external incoming pin - in this case c12in2- (pin 14)
CM2CON0.0 = 0       'this bit with bit 1 set the external incoming pin - in this case c12in2- (pin 14)

' Setup the internal VREF
VRCON.7 = 1         'Comparator1 CV Ref enable bit
VRCON.6 = 1         'Comparator2 CV Ref enable bit 
VRCON.5 = 0         'high or low range  0 = High Range, 1 = low range
VRCON.4 = 0         '0.6V Reference Enable bit   ....0 is disabled
VRCON.3 = 0         'these 4 bits set the divider of the VREF ladder 16 values - 7 should yield 1/2 VCC
VRCON.2 = 1         'these 4 bits set the divider of the VREF ladder 16 values - 7 should yield 1/2 VCC
VRCON.1 = 1         'these 4 bits set the divider of the VREF ladder 16 values - 7 should yield 1/2 VCC
VRCON.0 = 1         'these 4 bits set the divider of the VREF ladder 16 values - 7 should yield 1/2 VCC


Comp1Time       var  word    ' used to amalgamate TMR1 High & Low Bytes.
Comp2Time       var  word

      
INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System  PO90OOO9
INCLUDE "ReEnterPBP.bas"     ' Include if using PBP interrupts

ASM
INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   CMP1_INT,  _Comp1_Int,   PBP,  yes
        INT_Handler   CMP2_INT,  _Comp2_Int,   PBP,  yes
    endm
    INT_CREATE               ; Creates the interrupt processor
ENDASM

T1CON.0= 1  'start timer

Comp1Time = 0 'clear down Comp1Time, prior to starting.
comp2Time = 0  'clear down Comp2Time, prior to starting

@ INT_ENABLE  CMP1_INT     ; enable Comparator 1 interrupts
@ INT_ENABLE  CMP2_INT     ; enable Comparator 2 interrupts

'Main body of Code****************************************************************
Main:
        HSEROUT ["comp1=",dec Comp1Time,9,"comp2Time=", dec comp2time, 13, 10]
        PAUSE 80
        goto Main
        end       

'Comparator1 Interrupt Handler++++++++++++++++++++++++++++++++++++++++++++++++++++ 
Comp1_Int:
        Comp1Time.Lowbyte = TMR1L       'Store timer1 Low into a variable  
        Comp1Time.Highbyte = TMR1H      'Store timer1 high into a variable.
        TMR1H = 0                                   'Set the high part of the timer value to 0
        TMR1L = 0                                    'Set the low part of the timer value to 0

@ INT_RETURN


'Comparator2 Interrupt Handler++++++++++++++++++++++++++++++++++++++++++++++++++++ 
Comp2_Int:
        Comp2Time.Lowbyte = TMR1L       'Store timer1 Low into a variable 
        Comp2Time.Highbyte = TMR1H      'Store timer1 high into a variable.
        TMR1H = 0                                  'Set the high part of the timer value to 0
        TMR1L = 0                                   'Set the low part of the timer value to 0
        
@ INT_RETURN