wanna know about delay in ADC

engr.hayee said:

Hi,
I am working on 18f452.I have some Analoge Channels Some digital Inputs.Exactly i want to know that is it necessary to add a delay in adc routine for example

Code:

set_adc_channel(2); 
  delay_ms(5); 
  ts1=read_adc(); 
  ts2=(ts1*0.488);//ts2=((ts1*5)/1023)*100 => ts2=(ts1*0.488) 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  hold_regs[10]=ts2;//loading value of ts2 in holding register

Here the delay is too much because i want to run the entire program in 55uS.My program consists of 4 analoge channels so it would be take too much time.

i used another technique.i have initialize a counter.when a conter reaches at a particular value it read adc like

Code:

set_adc_channel(2); 
if(counter==2400) 
 { 
  ts1=read_adc(); 
  ts2=(ts1*0.488);//ts2=((ts1*5)/1023)*100 => ts2=(ts1*0.488) 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  rotate_left(&ts2,2); 
  hold_regs[10]=ts2;//loading value of ts2 in holding register 
  }

But by doing this when i vary any one analoge channel by potentiometer all analoge channels varies.
Tell me another way for doing this

Click to expand...