16F819 ADC 8bit=127, Not 255?Help!

[Accelerator]

Hi ladies and gentlemen,

I'm very new to this forum, as well as the PIC world, and I have a simple code below to test my PIC16F819 's ADC function. I am trying to set the ADC as a 8-bit converter, however, it turned out that the value only goes up to 127, not 255 (if you refer to the code below, the value of "counter" only displayed up to 4, instead of 9, and my servo only turned half way...). By the way, my analog test input for PORTA.0 is from 0v to 5v.

I'm stuck and I have no clue of what I have done wrong, would anyone please help me out?!

Thanks in advance!

regards,
Accelerator

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@ DEVICE PIC16F819, INTRC_OSC_NOCLKOUT, WDT_OFF, LVP_OFF, PWRT_ON, PROTECT_OFF, BOD_OFF

include "modedefs.bas"

DEFINE OSC 8 'set the clock to 8 Mhz
OSCCON = $70 'set the clock to 8 Mhz, 60 for 4MHz
'set up the analog to digital converters
DEFINE ADC_BITS 8 'set # of bits
DEFINE ADC_CLOCK 1 'set clock source(1=internal 8MHz, 3=rc)
DEFINE ADC_SAMPLEUS 50 'set sampling time in ms
ADCON1 = 0 'set PORTA pins to analog
TRISA = %00000001
TRISB = %00000000

COUNTER var PORTA
LED var PORTB.7
POTENTIAL var byte

high led

SENSOR01:

ADCIN 0,potential

If potential>0 and potential<26 then counter = 0
If potential=>26 and potential<51 then counter = 1
If potential=>51 and potential<76 then counter = 2
If potential=>76 and potential<101 then counter = 3
If potential=>101 and potential<126 then counter = 4
If potential=>126 and potential<151 then counter = 5
If potential=>151 and potential<176 then counter = 6
If potential=>176 and potential<201 then counter = 7
If potential=>201 and potential<226 then counter = 8
If potential=>226 and potential<255 then counter = 9

pulsout PORTB.0, potential

goto sensor01
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