PIC18F45K22 ADC Problem

[mryldz]

Hi everyone,

I've a small question, I only need a working code for ADC and it has to be like these type. I write these codes, but it doesn't work on circuit. So, where is the mistake in these codes given below. Maybe it is about "fuses" ?

[Ttelmah]

First, you must only enable one oscillator.

Currently you have 'XT', which says to use an external crystal, and
'INTRC_IO' which says to use the internal oscillator, and enable I/O on external oscillator pins.

Then you must _never_ enable an interrupt without a handler. You don't want INT_AD enabled. This is only used when you are using a hardware event to enable the ADC (CCP for example), which you are not doing, and enabling it without a handler will crash the code when the ADC completes.

Then you have the ADC set to only return 8 bits. (ADC=8)....

Then don't use floats. Seriously, either use ADC counts, or convert to a scaled integer. Float maths should be avoided unless it is completely necessary. It is bulky, and slow.
As written, it is always going to be >0. ADC values are always positive, and you are adding '1', so the value is going to be 1, 1.00193 etc.. Never -ve.

Then you should only select the ADC channel once, outside the loop.

[gpsmikey]

Well, without my morning coffee yet, the first thing that I see is how would "fb" ever be less than 1? You are adding some unsigned number times a positive coefficient to 1. That will always give you "1+something". Since you don't say exactly what "doesn't work on circuit" means, that is the first thing I notice. Since you are testing for "fb>0" that will always be true.

mikey
_________________
mikey
-- you can't have too many gadgets or too much disk space !
old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3