hello everybody​

im new here and looking for ur help all
i'm doing heart sound monitoring system that detects and amplifies the heart sound and then displays the waveform of the sound on graphic LCD by using PIC16F877A​

i need to understand few things befor i start my project!​

how much input voltage in range can the PIC16F877A recieve (output of the ampified signal )!? bcz i want to amplify the signal but i want to know until whic range of values!!
it's a sound signal so that means the output will be fed in to the ADC of the PIC!!​

i searched on the datasheet but im very new on PICs so couldn't really understand it!​

thank you​

 

A regulated 5V power supply should be sufficient to power up PIC. Can use LM7805 regulated IC if you want to.

 

The signal on the ADC inputs can be between 0V and the supply voltage (normally 5V)

 

A regulated 5V power supply should be sufficient to power up PIC. Can use LM7805 regulated IC if you want to.

thank you for ur reply, but what i mean here is the output of the amplified signal which is the input to ADC of pic..!

what u mentioned here was the operation voltage!!
thank you

 

The signal on the ADC inputs can be between 0V and the supply voltage (normally 5V)

thank you for ur answer,
so that means it doesn't receive negative voltages! right?

on the data sheet i read something about Vref, can u explain to me what's it exactly ?

 

This link may be of some help http://www.mikroe.com/en/books/pic-books/mikroc/ together with the data sheet. Also your PIC can not measure negative voltages. But if you have a bipolar signal, you can "lift" it up to Vref/2.

 

I didn't use PIC before, but MSP430 instead. I think when you use ADC in PIC, you can use the chip power supply(5V) as reference which others mentioned above, or you can input another voltage as a reference, but make sure the maxium voltage the pin can afford in datasheet.