Reading A Photo Resistor using ADC

[DynamoBen]

Bruce felt that a photocell would be to slow to measure frequency. That is why I asked about a solar cell.

[TonyA]

Yeah, I see. I glanced over what Jessey said about measuring the difference between dawn and dusk... I know the photocell with adcin would work great for measuring changes in light, but dawn and dusk, or measuring the frequency of light. I don't know if the photocell could do that.

(Sorry for any confusion caused by my posts in this thread, I was replying to Jessey's original post about using a photocell. I didn't read the replies posted by others.)

[jessey]

Hello Bruce,

Thanks for the info, I was really getting frustrated with the pot command and finding a proper value of a photo resistor to use.I found that the adc works great with just about any photo resistor value.

Also thanks TonyA and your right that the adc does work best for this type of application and it is very fast too, I'm pleased to see. I'm also using an 18f452 (great micro) but not with the ADCin command and it works great.

Check_The_Light_Level:
  adcon1=%00001110   ' AN0 analog, all other pins digital 
  ADCON0 = $41       ' Set A/D to Fosc/8, Channel 0, On
  Pauseus 50         ' Wait for channel to setup         
  ADCON0.2 = 1       ' Start conversion
  Pauseus 50         ' Wait for conversion
  Lite_Level = ADRESH
  ADCON1 = 7         ' shut off (Disable) ADC 
RETURN

Once again thanks everyone for getting me kick started on this.

Thanks
jessey