AD conversion

[CipiCips]

I am using PIC 16f877A

this is the code


DEFINE ADC_BITS 8 ' Set number of bits in result
DEFINE ADC_CLOCK 3 ' Set clock source (rc = 3)
DEFINE ADC_SAMPLEUS 50
ADCON1 = 0 ' PORTA is analog
pw VAR BYTE
TRISA = 255
TRISD = 0

start:

ADCIN 0,pw

if (pw > 220) and (pw<252) then
pulsout portd.3,220
else
goto start
endif
goto start

This program works, when I move Joypad to the right motor move to the coresponding postion, I wanna know what is the right value of variable pw, when my joypad is moved al the way to the right and al the way to the left??

[mister_e]

OK, so you have the results left justified, it should work. BUT maybe you have some nifty noise on the line or something like that. Allow a certain error margin.



test 0
If pw<5 then

test 255
if pw>250 then


still stucked?!? well let's try a variant of it

Test 0
if ADRESH<5 then

test 255
if ADRESH>250 then

about now?

[CipiCips]

So this ADRESH is the adress where AD save it's value ?

what if I have two, three or four AD, is it all stored in same adress ?

[mister_e]

Yup they all have the same register.

ADCIN select the channel, perform the conversion, then read it from ADRESH/ADRESL register, then dump it to your variable.

[CipiCips]

thx Steve

I will probably have few questions, now I will contion on my work

thx