Audio signal reading using PIC8720

[csshah]

Hello
Finally I found out how ADC works in PIC but now the porblem is I want to read audio signals and as told by somebody yesterday pic cant convert the portion of the signal below ground. So still is there anyway I can read signals and convert them to dB using PIC without using any other hardware like rectifier or level shifter...


thanks in advance

[bluetooth]

Put a divider that sets the a/d input at half-scale and ac couple the audio signal into that point.

[newguy]

What you want to do is no simple task. It sounds like you want to create an SPL meter (sound pressure level). If this is what you want, it's not easy to create an accurate one.

You will need an rms-to-dc converter. The most popular are Analog Device products. Here is a link to the AD636:
http://www.analog.com/en/prod/0%2C2877%2CAD636%2C00.html

Here is "the bible" of rms-to-dc conversion, the AD application guide:
http://www.analog.com/en/content/0,2886,773%255F866%255F15010,00.html

It seems to me that years ago I found a link to a homemade quasi-SPL meter, but I can't find it now. Google "spl", "schematic", and any other terms you can think of, and you may find something acceptable if accuracy isn't important.

[csshah]

hi
thanks for help. actually i dont want to read the value of siganl precisely, i m intending to move a bar depending on audio signal. so i just want an approximate value to move the bar. so if u guys know any proportinal equation or any hint regarding this would be highly appreciated!!!

thanks

[csshah]

hi
thanks for help. actually i dont want to read the value of siganl precisely, i m intending to move a bar depending on audio signal. so i just want an approximate value to move the bar. so if u guys know any proportinal equation or any hint regarding this would be highly appreciated!!!

thanks

[bluetooth]