Mega128 ADC and VU meter ?

Go To Last Post
8 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Guys,

 

Does anyone know on how to use ADC as a VU meter ? I want to display the result to LCD...

Any clues ?

 

Thanks for reading

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Lots of pertinent Google hits for "atmel avr vu meter", many of which point back to this site.

 

For one channel, many use LM3915 or equivalent directly as it has log operation built in.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Ok, thanks for the suggestion.....if it has two speakers....means I will make two channel ? thanks....

So no ADC required.....I have read about LM3915 before....but it can not display to my LCD, can it ??..

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

As usual, you've asked first before doing any research.
Do you know what a VU meter is and what it displays?
Do you know what dB is? Google decibels.

Have you written code to show the bar graph on the lcd yet? That might be a start. Then you need to get the adc value, scale it then display.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

@Kartman, I prefer asking to someone who had done it than asking Google...it's a machine and I'm human....;)

I had done bar graph before but analog version one for my amplifier...

Thanks for the clue...

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I googled avr vu meter

and got heaps of hits. Or are you up for a round of annoying all and sundry with your laziness?

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

There are 2 things to fret about with VU meters... the power level and the peak level. If you have 50 watt speakers, and you have a 50 watt amp, it will sound like dog breath, because there isn't enough oomph to reproduce the peaks. If the peaks are 3dB or 6dB above the average, you need 2 or 4 times the watts. But if you have a 200W amp driving your 50W speakers, you need to watch the temperature in the voice coil, which is proportional to the rms voltage measured with a slow time constant. The 50W voice coil can take 50W for hours, or 100W for a minute, or 200W for a couple seconds, so you need a VU meter that shows rms voltage over the last couple of seconds. This is proportional to the heat in the voice coil. Know how to calc the rms of the a/d samples?

 

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Did you try to display a variable number of characters on a line of your LCD?

Did you try to convert a value into its logarithm (to have a decibel meter)?

Did you try to manage that , for the maximum value, each and every character is displayed -and, for the minimum value, noone is displayed, of course ? leading to the rather trivial formula:

number_of_Chars= (16 * value)/(Max-Min) //I suppose you have got 16 chars on your display...

(that would be an horizontal vumeter, differing from Kartman's vertical one using only one character per channel -I prefer Kartmans solution/hint...- )...