8 channel voltmeter (help)

[arash]

Hi.
I was make 8 channel voltmeter (0-5) with diffrent inputs.It works good in proteuse but in real  when i  connect a voltage to channel 0, it's affect will change the other channels voltage.How can i solve this? (use ht-picc compiler to see my prj)
Thanks.

[adidav]

Hi, I think the problem is after a conversion have place you have to wait 2Tad time. For example using 16F877 you will have to wait 20uS.

main()
{

resultCh0 =  ADC_Conversion(Channel0);
DelayUs(20);
resultCh1 =  ADC_Conversion(Channel1);
DelayUs(20);
.
.
.
.
resultCh7 =  ADC_Conversion(Channel7);
DelayUs(20);

}

I hope this will help you.

Greetings,
ADi

[entekelektronik]

Yes, You must put delay routins after the conversion every channel.
good luck.

[ahmetefegumus]

be careful,
can you check ADC setup configuration where beging of the program. Normally 20 us time is enaugh.
I am added a little code for you, 
may be helper for you.

         enable_interrupts(int_ad);
         set_adc_channel(0);
         delay_us(20);
         _value_volt= read_adc(ADC_START_AND_READ);


Posted on: February 19, 2008, 05:11:23 17:11 - Automerged
I want to add something  to my last written. can you put delay in main rutin because system repatly read adc like a contıously all the time. if the system is weating a litte time as a idle condition ( 0.5 msn) and then reading adc , may be problem solved.