Thilo, just to quick questions:

1. what is the purpose of 1N4001
2. how it limits the voltage swing on 100nF the group of resistors of
150 +470 ohm

Please add reference designators to all of your components when you
show someone a schematic.

best wishes,
Vasile

On 1/29/07, Thilo Klein <ostentativ@arcor.de> wrote:
> Dear Readers.
>
> Currently I am using the setup whose picture can be found at
> http://forum.microchip.com/tm.aspx?m=223874. This is a part of the
> whole as I focused on the ADC and PIC here. I am writing this to
> forestall recommendations regarding a quarz for instance. This is a
> Delta-Sigma ADC from AN700. According to my calculation I adjusted it
> to measure an area of about 10 to 80% of the resistor's value.
>
> Unfortunately in exactly this area there is happening nothing, there's
> one value all the time. If I am rotating in the area being defined as
> out-of-range there a distinction is made.
>
> What could be the problem, what to change ?
>
> My code in PicBasicPro:
>
> Define OSC 8
>
> ;Variables
> result_l VAR BYTE BANK0 SYSTEM
> counter VAR BYTE BANK0 SYSTEM
> result_h VAR BYTE BANK0 SYSTEM
>
> ;Register
> OPTION_REG = 0
> TRISA = $01
>
>
> ;Interrupts
> INTCON = 0
> VRCON = $EC
> CMCON = $06
>
> Start:
> GOSUB Value
> StartV = ADCValue
> Pause 10
> GOSUB Value
> EndV = ADCValue
> IF StartV = EndV THEN
> Low GreenLED
> High YellowLED
> ENDIF
> IF StartV != EndV THEN
> High GreenLED
> Low YellowLED
> ENDIF
> GOTO Start
> END
>
>
> Value:
> GOSUB Value2
> ADCValue = result_l * 256 + result_h
> RETURN
>
>
> Value2:
> ASM
> DeltaSigA2D
> clrf     counter
> clrf     counter+1
> clrf     result_l
> clrf     result_h
> movlw    0x03    ; set up for 2 analog comparators with common reference
>  movwf    CMCON
> loop
>       btfsc    CMCON,C1OUT ; Is comparator high or low?
>       goto     complow      ; Go the low route
> comphigh
>       nop                      ; necessary to keep timing even
>       bcf      PORTA,3     ; PORTA.3 = 0
>       incfsz   result_l,f   ; bump counter
>       goto     eat2cycles    ;
>       incf     result_h,f    ;
>       goto    endloop        ;
> complow
>       bsf      PORTA,3   ; Comparator is low
>       nop                      ; necessary to keep timing even
>       goto     eat2cycles   ; same here
> eat2cycles
>       goto     endloop    ; eat 2 more cycles
> endloop
>       incfsz   counter,f   ; Count this lap through the loop.
>       goto     eat5cycles    ;
>       incf     counter+1,f  ;
>       movf     counter+1,w  ;
>       andlw 0x04            ; Are we done? (We're done when bit2 of
>       btfsc   STATUS,Z    ; the high order byte overflows to 1).
>       goto     loop       ;
>       goto     exit
> eat5cycles
>       goto     $+1         ; more wasted time to keep the loops even
>       nop                      ;
>       goto     loop     ;
> exit
>       movlw    0x06     ; set up for 2 analog comparators with common reference
>       movwf    CMCON
> ENDASM
> RETURN
>
>
> Green is on if there's movement(so values change) and yellow if there's none.
>
> Regards
>
> TK
>
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