seeing some readings when doing ADC on a channel giving a dec value 5534, 5144, ect when using ADCIN
have defines set to 12 bit
the adc channel is grounded via 26k resistor for testing
problem is i cant see why the reading is there at such a high value , and the value should not exceed 4095
any thoughts on why this may be happening ?????????
cheers
sheldon
have defines set to 12 bit
the adc channel is grounded via 26k resistor for testing
problem is i cant see why the reading is there at such a high value , and the value should not exceed 4095
any thoughts on why this may be happening ?????????
cheers
sheldon
Code:
DEFINE OSC 32 ' Timing referance for pause , pauseus commands
DEFINE ADC_BITS 12 ' Number of bits in ADCIN result - Required for adcin command
ADCON1 = %00100000 ' bit 7-6 = TRIGSEL 11= triger from RTCC, 10 = trigger from timer1 ,01 = trigger from CTMU, 00= trigger from ECCP2
' Bit 5-4 - VCFG+ 11= Internal VREF+(4.096v) ,10= Internal VREF+ (2.048v) 01=External VREF+ ,00= AVDD
' Bit3 - VNCFG- 1= External Vref- , 0= AVSS Vref/A ,
' Bit 2-0 = Analoge Neg Ch Select ( Differential measurement )
' 111 = AN6, 110 = AN5, 101 = AN4,100 = AN3,011 = AN2, 010 = AN1, 001 = AN0,000 = AVSS,
ADCON2 = %10010010 ' bit 7 = 1 ADFM ( ADRESH, ADRESL - right justify ) , Bit6 n/a ,
' Bits 5-3 ACQT ( acquision time ) 111 = 20TAD ,110=16TAD,101-12TAD,100=8TAD,011=6TAD,010=4TAD,001=2TAD,000=0TAD
' Bit 2-0 ADCS ( AD clock sel) x11 =FRC , 110=Fosc/64,101= FOSC/16 ,100=FOSC/4 ,010=FOSC/32 ,001=FOSC/8, 000=FOSC/2
' Note: define ADCIN clock and define ADcin sample overide this setting
ANCON2.1 = 1 ' Set PortG.3 = 1 - Select portG.3 to Analog - AN17 - AD touch switch input 1R-TX mode
TRISG.3 = 1 ' Set TRISG.3 = 1 - Select portG.3 to Input - AN17 - AD touch switch input 1R-TX mode
ADCON0 = %01000111 ' Select the A/D channel - AN17 turn on a/d
adcin 17,value1 ' do ADC reading on AN17 - touch switch input
HSEROUT2 ["value1 = ",dec4 value1,13,10]
ADCON0 = %01000100 ' Select the A/D channel - AN17 and turn off A/D moduleCode:
value1 = 0003
value1 = 0004
value1 = 0002
value1 = 0011
value1 = 0005
value1 = 0003
value1 = 0004
value1 = 0004
value1 = 0005
value1 = 0006
value1 = 0004
value1 = 0003
value1 = 0005
value1 = 0004
value1 = 0004
value1 = 0004
value1 = 0003
value1 = 0005
value1 = 0002
value1 = 0002
value1 = 0005
value1 = 0005
value1 = 5535
value1 = 5525
value1 = 0004
value1 = 0008
value1 = 0002
value1 = 0001
value1 = 0004
value1 = 0002
value1 = 5534
value1 = 5532
value1 = 0005
value1 = 0077
value1 = 5529
value1 = 0004
value1 = 0008
value1 = 0020
value1 = 5524
value1 = 5229
value1 = 0025
value1 = 0057
value1 = 0002
value1 = 5283