hello everybody

i have simple Question here but since im new dealing with PICs i need an answer for my question!!

i'll be using pic16F877A to display a waveform of heart sound of graphic LCD!

i just wanted to know the range of maximum and minimum input voltages to the ADC of the PIC16F877A ! in other word how much the voltage range of the amplified signal must be in order to be received by the ADC ??


thank you ​

 

hello everybody

i have simple Question here but since im new dealing with PICs i need an answer for my question!!

i'll be using pic16F877A to display a waveform of heart sound of graphic LCD!

i just wanted to know the range of maximum and minimum input voltages to the ADC of the PIC16F877A ! in other word how much the voltage range of the amplified signal must be in order to be received by the ADC ??


thank you ​

Did you read the datasheet? It is in there. Probably0-5VDC or maybe 0-3.3 .

But is will be in the datasheet.

 

You have asked the same question here http://forum.allaboutcircuits.com/showthread.php?t=33964 Please stay in one thread.

 

i did read the data sheet but since im new to it i couldn't understand! bcz it mentions something about Vref and i don't undrestand what's meant by Vref!!?

how if i have a bipolar signal, how can pic read it !!?

thank you

 

You have asked the same question here http://forum.allaboutcircuits.com/showthread.php?t=33964 Please stay in one thread.

sorry for that, i'll use previous thread..
can u jst explain to me what's Vref ?

thank you

 

sorry for that, i'll use previous thread..
can u jst explain to me what's Vref ?

thank you

Vref is the voltage reference for the pic's ADC, you can set this as an internal referrence or use an external reference tied to the Vref pin (RA3).... these settings can be found in the datasheet as well...


The maximum voltage the Pic ADC can accept is 5 volts.

To do an A/D Conversion, follow these steps:
1. Configure the A/D module:
• Configure analog pins/voltage reference and
digital I/O (ADCON1)
• Select A/D input channel (ADCON0)
• Select A/D conversion clock (ADCON0)
• Turn on A/D module (ADCON0)

2. Configure A/D interrupt (if desired):
• Clear ADIF bit
• Set ADIE bit
• Set PEIE bit
• Set GIE bit
3. Wait the required acquisition time.
4. Start conversion:
• Set GO/DONE bit (ADCON0)
5. Wait for A/D conversion to complete by either:
• Polling for the GO/DONE bit to be cleared
(interrupts disabled); OR
• Waiting for the A/D interrupt
6. Read A/D Result register pair
(ADRESH:ADRESL), clear bit ADIF if required.
7. For the next conversion, go to step 1 or step 2
as required. The A/D conversion time per bit is
defined as TAD.

My .02

 

how if i have a bipolar signal, how can pic read it !!?

thank you

You need to convert the signal from + - to 0 - 5VDC. 2.5 Volts would be your "zero". There are a number of oscope pic projects on the internet.

But this is a very big project for a newb. I should know. I am one.

You really should start with something like a DMM.