I am confuse

[timseven]

Hi, I am trying to use the 16f88 ability for read analog voltages. I need to use analog inputs RA0-RA3. My initial settings are as follows:

ANSEL = %00001111 'set RA0-RA3 as analog inputs
ADCON1 = %10000000 'Right Justifies 10-bit value
OSCCON = $60 'Sets the internal oscillator to 4 Mhz
DEFINE ADC_BITS 10 ' Sets the number of bits in the result to 10

ti var byte
ti = 50 '50 MILLISECONDS DELAY'
A var word ‘ A,B,C and D as variables
B var word
C var word
D var word

TRISA = %00001111
TRISB = 0 ‘Turn PORT B as outputs

I am using RA5 as my communication out to the LCD. (Internal clock). I am using also the 8 pins Portb for controlling two steps motors. Problem here is that if I ground the input pins (just for testing) I should get zero voltages and I don’t. I am using a 1K resistor to ground. For sure I am missing something here. Please advice.

[mackrackit]

With out seeing your code try setting the ADC for 8 bits and see what happens.

[Acetronics2]

Hi,

Set comparators OFF ...
ADCON0 = ?

Alain

[mackrackit]

I think this chip has the comparators off on reset. I need to double check.

Thinking more along the lines of not reading both the high and low bytes of the 10 bit setup might be the problem???

[Acetronics2]

Hi, Dave

you're right ... I never trust in defaults ... ( overhead, yes ... but sleeping nights ...)

what about this one :

TRISA = %00001111

RA5/MCLR/VPP bit 5 ST Input, Master Clear (Reset) or programming voltage input.

I am using RA5 as my communication out to the LCD

...

Alain

[mackrackit]

Alan,

That would make the display act funny