sixty9sandals

hi..
im very new..n i need someone guides to help me solving this problem. i try 2 display digital values in a row of 10leds by injecting 1.5V as an analog value with 5V as Vref..but the values displayed is 0100010010 instead of 100110011...why is this happen? any suggestion to solve it?my codes are as below..is there possibly caused by my wrong codes?

define ADIN_RES 10
DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 3
DEFINE ADC_SAMPLEUS 50

MEASURED_VALUE VAR word
REMAINDER0 VAR word
MEASURED0 VAR word
REMAINDER1 VAR word
MEASURED1 VAR word
REMAINDER2 VAR word
MEASURED2 VAR word
REMAINDER3 VAR word
MEASURED3 VAR word
REMAINDER4 VAR word
MEASURED4 VAR word
REMAINDER5 VAR word
MEASURED5 VAR word
REMAINDER6 VAR word
MEASURED6 VAR word
REMAINDER7 VAR word
MEASURED7 VAR word
REMAINDER8 VAR word
MEASURED8 VAR word
REMAINDER9 VAR word
MEASURED9 VAR word

TRISA = %00000001
TRISB = %00000000
TRISD.0 = %0
TRISD.1 = %0
ADCON0 = %11000101
ADCON1 = %10000000
pause 500


START:


ADCIN 0 , MEASURED_VALUE

REMAINDER0 = MEASURED_VALUE // 2
PORTB.0 = ~REMAINDER0
MEASURED0 = ( MEASURED_VALUE / 2 )

REMAINDER1 = MEASURED0 // 2
PORTB.1 = ~REMAINDER1
MEASURED1 = ( MEASURED0 / 2 )

REMAINDER2 = MEASURED1 // 2
PORTB.2 = ~REMAINDER2
MEASURED2 = ( MEASURED1 / 2 )

REMAINDER3 = MEASURED2 // 2
PORTB.3 = ~REMAINDER3
MEASURED3 = ( MEASURED2 / 2 )

REMAINDER4 = MEASURED3 // 2
PORTB.4 = ~REMAINDER4
MEASURED4 = ( MEASURED3 / 2 )

REMAINDER5 = MEASURED4 // 2
PORTB.5 = ~REMAINDER5
MEASURED5 = ( MEASURED4 / 2 )

REMAINDER6 = MEASURED5 // 2
PORTB.6 = ~REMAINDER6
MEASURED6 = ( MEASURED5 / 2 )


REMAINDER7 = MEASURED6 // 2
PORTB.7 = ~REMAINDER7
MEASURED7 = ( MEASURED6 / 2 )

REMAINDER8 = MEASURED7 // 2
PORTD.0 = ~REMAINDER8
MEASURED8 = ( MEASURED7 / 2 )

REMAINDER9 = MEASURED8 // 2
PORTD.1 = ~REMAINDER9
pause 100
GOTO START


END

hope somebody willing to lend me help
thank you..

Attached Images

resize.jpg (89.1 KB, 4 views)

Papabravo

1st: You seem to be witing a command to do a conversion, read a value and writing it to the LEDS. Don't you have to wait for the conversion to be complete BEFORE reading the result?

2nd: Don't you have to insert some delay in between one A/D conversion and the next?

3rd: You gave the value of the analog input voltage, but you didn't tell us what the reference voltage was. How can we know if the value you are getting is correct or the value you expect is correct?

4th: Ohhh..never mind

atferrari

5 V the Vref?

__________________
Agustín Tomás
In theory, there is no difference between theory and practice. In practice, however, there is.

sixty9sandals

mmm..ya..the Vref value is 5V..as im using adcon1=10000000 which is Vref=Vdd=Vss...pls do correct me if im wrong..im too new to all of this thing..n im using pic 16f877

thank you

eng1

You have to check when the GO!DONE bit (ADCON0.2) has been cleared by hardware (conversion completed), if this is not done by the ADCIN instruction (?). Is that a built-in function of your compiler?
You may try with 8-bit resolution and 8 LEDs for a start. Are you sure that you're reading both ADRESH and ADRESL registers with one instructon?

Papabravo

You went back and edited your original post! Now we have no frame of reference for the discussion.

Says me if 5V is the reference and 1.5V is the input you should get
That's assuming that your code can correctly do an A/D conversion and that it is reading a real result insted of an intermediate value. The value that you got is 274 which is certainly close to 307. In voltage terms it is 1.33 volts. How accurate is your Vcc and how accurate is the measurement of the input? Are they rock solid or do they have some ripple riding on top of them?