how to get an analog potentiometer to settle down?

[keithv]

I'm working on a project that uses the ADC to read an analog potentiometer. It's causing problems for me when the voltage on the ADC fluctuates slightly. Like when the voltage it's reading is 2.4955V and the ADC can't make up its mind whether it's 2.49V or 2.5V. Is there a way to make the voltage settle down?

[keithv]

Can I decrease the resolution of the ADC?

[towlerg]

or just round the output .

[keithv]

or just round the output .

How do I do that? Is there a command line that will round up or down?

[CuriousOne]

Yes, there is such command, but I don't remember it's name, check the manual, it was something like I=I<<I or whatever.

[HenrikOlsson]

If you DEFINE ADC_BITS 8 it will grab the 8 high bits of the 10bit result from the ADC, you'll leave the noise in the lower two bits but at one point or another you're still going to be on the edge where the 3rd bit is flipping back and forth and you're back at square one.

You can always take multiple samples and average them to smooth things out a bit.

/Henrik.

[keithv]

I haven't tried the sampling/averaging fix yet. I'm having some trouble with the new 16F616. With the 16F676, the only problem I had was with the pot not wanting to settle. Now, there's all kinds of problems with the 16F616. It seems like the primary difference between the two chips are the comparators. I'm a little confused by the differences between the 16F676's CMCON register and the 16F616's CM1CON0 and CM2CON0 registers. Seems like if I want CM1CON0 to be configured the same as CMCON = %00000111, I would write it as CM1CON0 = %00000000, but the last 2 bits are a little confusing to me. Do I need to configure both the CM1CON0 and CM2CON0 registers?

Also, could the way I have ADCON1 configured be causing trouble? Seems like FOSC2 is what I want. Faster is better, right?

Below is the configuration section of my code for the 16F616. Sorry for so many questions. I'm still pretty new to this.

#config 
    __CONFIG _CP_OFF & _WDTE_OFF & _BOREN_OFF & _PWRTE_ON & _INTRC_OSC_NOCLKOUT & _MCLRE_OFF
#endconfig


ADCON1 = %00000000
ANSEL = %00000110
CM1CON0 = %00000000               'program worked previously with 16F676 CMCON = %00000111   

TRISA = %00001111
TRISC = %00000000

' Set TMR0 to interrupt every 16.384 milliseconds
   OPTION_REG = %10000101        ' Set TMR0 configuration and enable PORTB pullups
   INTCON = %10100000           ' Enable TMR0 interrupts
   On Interrupt Goto tickint