LCD BARgraphs

[savnik]

Hi, Darrel

Looks you're perfectly right ... the PIC ADC does not have the 60 dB dynamics(? ... I meant range !!!) our friend Ioannis looks for.

IF you were involved in radios ... may be the ref. "CA3089" will remind you some Vu-meter designs ... ( Use of pin 13 ...)

So, If we used such a Log amplifier to translate from Log to lin scale ... we could easily get this 60 dB Scale ... may be more !!!

Of course ... the drawing is in my Dataroom ... and I still must have a PCB somewhere !!! ( Was a very old Elektor application for an Audio Level-meter ( Sonometer) ... as the CA3089 can work with audio frequencies ... )

Read you soon

Alain

PS: found another with a NE604 Chip ...70 dB covered !!! ... heeuuuuuu file weights ... 325 kB DAMNED !!!

Hi, Savnik

+ 3 dB means the double ... for whatever you want.

but + 6 dB for Power means +3 dB for corresponding voltage

CA3089 is a monolithic integrated circuit that provides all the functions of a comprehensive FM-IF system, which include a three-stage FM-IF amplifier/limiter ,a doubly-balanced quadrature FM detector.

[Ioannis]

Thanks Alain for the ideas. I suppose one has to do it in practice and check the response of the circuit.

The PIC is not yet defined. I will choose one after we will end with the spec's (memory needed etc).

mmm, kinda mix with embedded strings in your code space and lookup table...
So the Excel sheet would have to pack it in 14Bit and later you use DA.

How's that sound? pretty bad to me as the unpacking method will certainely be slightly longer to execute than reading a single Byte for a DT, DW table ...

Steve, I agree that I have to pay for the extraction in terms of speed. But then, I guess, somewhere in the program there will be a point needing mcu power as it seems.

Now, Darrel, as Nikos (Savnik) stated, 3db is indeed a double or half the power. But as for voltage, you need 6db.

db(Watts)=10*LOG*(P1/P2)

db(Volts)=20*LOG*(V1/V2)

For the case we discuss, replace the V2 with 0.775Volts or the P2 with 1mW.

If you make the maths you can prove it.

Relative to the dynamic range, well I have to measure from 7.75mV up to 1.55 RMS or from 11mVpk up to 2.19Vpk. Lets make it easier and the MAX be 2Vpk.

I will Scale it to max 5Volt (x2.5), so the minimum will be 11mV*2.5=27.5mV.

For a 10-bit ADC the LSB will be 4.88mV, so a 10-bit ADC will be enough for a 46db dynamic range. If I am wrong please correct me.

Now, about the CA3089 or the better one that I used long ago, CA3189. Where does this chip fit here?

A big thank you to all responded.

Ioannis


P.S. The idea of Select Case may also be a nice alternative since for every BAR in the Bargraph there are alo of values to fit. It will be a long Select case of course... I have to try it.

[Acetronics2]

CA3089 is a monolithic integrated circuit that provides all the functions of a comprehensive FM-IF system, which include a three-stage FM-IF amplifier/limiter ,a doubly-balanced quadrature FM detector.

AND a level detector output at pin 13 ....

AND it works down to audio frequencies too ...

AND NE604 an CA3089 show same functionnal blocks ( of interest here ...) inside

Alain

[Acetronics2]

Hi, Ioannis

could you PM me a mail adress for sending the scheme... ( and explanations of the NE 604 use ... if you can read French ( sorry ...))

Alain

[Darrel Taylor]

Alain,

Finally got a chance to run your bargraph. (it works)
But I'm still not crazy about the 5-bars. Here's what it looks like
<script type="text/javascript"src="http://www.pbpgroup.com/DT_INTS-14/V-LCD_Disp.js"></script>
<script type="text/javascript"src="http://www.pbpgroup.com/js/AceBargraph.js"></script>
It's not as noticable when it moves fast, but that jump is still there.

And while it compiles to about 100 words less than mine, it doesn't have all those features like placing it anywhere on the screen, making it any width of characters, scaling the input values to any range up to 32768, multiple bars on the screen and 3 different styles.

But it definately does a 1-line 3/5-bar graph.

[Ioannis]

AND a level detector output at pin 13 ....

AND it works down to audio frequencies too ...

AND NE604 an CA3089 show same functionnal blocks ( of interest here ...) inside

Alain

Well, I tested NE604 and was amazed at Audio freqs. A nearly 65dB range was obtainable on a breadborad! Incredible! So the LCD_Bargraph has now a friend for audio signals making great VU-meter. One catch is that NE604 is expensive one. Here about 10 Euros in small qts. Thanks Alain for the tip.

C/O Darrel:

While trying to develop my project using your interrupts, I stuck on, I think for sure, stupid one. The attached sample code does not respond to PORTB.0 interrupt. Is there any mistake I 've made and can't see?

Ioannis

[Acetronics2]

Hi, Darrel

Yes, ... I know the big problem at "high speed" is unequal calculating times upon the place pointed at ...
but we must remember it's not a GLCD ... "some holes in the somewhere" ...

Your picture's really nice !!! ...

By the way ... I have a beautiful 122x32 GLCD here ... hmmmmmm, I might give a look to that !!!

read you soon

Alain

[skimask]

By the way ... I have a beautiful 122x32 GLCD here ... hmmmmmm, I might give a look to that !!!
Alain

I've got some 'pre-fab' code for the 122x32 types. Nothing wild, just the basic setup/configure routines, some basic 'x,y' plotting, and some text output routines. But it works great for me...

EDIT: I just started a new thread with the code described above attached. Again, nothing fancy, but I've been using the same block of code for a couple of years now...

[Darrel Taylor]

C/O Darrel:

While trying to develop my project using your interrupts, I stuck on, I think for sure, stupid one. The attached sample code does not respond to PORTB.0 interrupt. Is there any mistake I 've made and can't see?

Ioannis

Possibly...

OPTION_REG = $81 ; Set TMR0 Prescaler to /2, RBPU on

The comment says RBPU on, but it's actually leaving the pull-ups turned off.
<br>

[Ioannis]

Thanks Darrel, but it really doesn't matter since there is a real resistor for Pull-up on the pcb (Picdem2+).

I have not found why is not responding...

Ioannis

[Darrel Taylor]

Ioannis,

I can't see any other problems with the program. Or, any reason why it wouldn't work with the PICDEM2+.

Which PIC are you using with the PICDEM?
<br>

[Ioannis]

Currently the 16F877. I have handy also other to try. Maybe a 18F452.

To be sure that Portb.0 is OK, I tested with a simple loop of the kind:

while portb.0=1
wend
high LED1

and worked OK. So electrically there is no problem.

PICDEM2+ is connected to ICD2 working in programmer mode only. So, there is for sure no other source of interference.

Skimask: could you post the link you mentioned? Thanks

Ioannis