Spectrum analyzer with PIC16F877A

Status
Not open for further replies.
A

alifred

Member
Hi,

I was wondering if anyone knew anything about audio spectrum analyzers?
I am currently trying to make one on a LCD display (2x16 squares, 5x8 dots per square) but I cannot see how I can draw straight lines on the display.

If anyone has any ideas, I would be very grateful. I know how to divide the input into the different channels to display, but not how to actually display them!

I want something like this: YouTube - Pic 16F688 HD44780 Spectrum Analyzer

Thanks

Fred
 
Last edited:
If you look on the PICList there's on old project for making a spectrum analyser using a 17 or 18 series PIC, directly generating an LCD display.

Essentially you need FFT (Fast Fourier Transform).
 
Hi,

Thanks for that but it doesn't seem to interface with a LCD alphanumeric display.

Could I adapt it to work with my display?

Thanks for the fast reply,

Fred
 
alifred said:
Hi,

Thanks for that but it doesn't seem to interface with a LCD alphanumeric display.

Could I adapt it to work with my display?
Click to expand...

Presumably you could?.

For the display you presumably just need to define custom characters.

But why not just check the software for the video you posted the link to?, the software (in C) is available to download.
 
Last edited:
Hi,

1. I didn't realize that the c code was available from the video, thanks for pointing that out!
2. How would I define custom characters?
I am only 14, so don't have a big rage of knowledge on everything, but am I right in thinking that I can program a PIC to define the custom characters?

Thanks for all your help!

Fred
 

Yes, as the code in the link does - have a look at that.
 
..pls has anyone any idea on how to go around the codes to display an audio signal spectrum using a 16x2 Lcd?

thanks
Ade
 
Ultimately, Fred and Myself have yet to build any form of spectrum analyzer, but in the research for it, we concluded the following points:
  • To display using a LCD, we would need to write custom characters to the LCD overwriting standard character's codes. Take a look at this site.
  • Using an ADC on the audio signal, on any PIC less than a dsXXXX would result in a very basic representation, (18F4550 has only 1024 steps). This would however give you an idea of the amplitude of the signal.
  • To work out the frequency domain (the whole point of a spectrum analyzer) would require performing a Fourier Transform to calculate the DFT. (To perform this at any useful rate lookup FFT's). This site should give you some basic ideas of how the FFT provides a frequency domain representation.

But, as I said, Freddie and I never got round to actually building the project listed.

is an example project using an FFT to perform spectrum analysis. (All in Assembler though)

Ali
 
badejavu1 said:
Hi Ali,
Thanks for the links.Yes I understand that it will be a basic representation of the signal because of my PIC's ADC resolution.
Click to expand...

You 'understand' wrongly, the PIC has a high resolution of 10 bits, giving 0.1% resolution. The lack of resolution would be down to the VERY limted resolution on the LCD.
 
Im looking for a bar type LED Dancing Spectrum display in cars. These wire thru speaker line. They were 2-2 1/2 in. wide and 10-11 in. long. You could program it for the LEDʻs to cross each other(like night rider but 3 crossing each other), or from the middle out, bounce.

I think it had 3-4 LED from top to bottom(ROW) and about 10+ length wise.

They stopped producing them and cant find anything on the WWW. Thanx James....
 
Status
Not open for further replies.

Similar threads

F
  • Question
Issue with Interfacing LCD with PIC16F877A
2
Replies
22
Views
6K
Farhaad
F
B
  • Question
Temperature controlled fan using PIC16F877a (in assembly language)
Replies
6
Views
4K
Dan Soze
D
G
  • Question
PIC16F877AA - NON-CONTACT THERMOMETER
Replies
9
Views
4K
rjenkinsgb
D
  • Question
How to create a Bitmap For a Dinosaur using PIC16F877A
2
Replies
33
Views
10K
Tocaboca
T
K
  • Question
Help with STM32G0
Replies
2
Views
3K
rjenkinsgb
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…