LCD BARgraphs

[Sean_Goddard]

I've been playing with the NCD/DCD with excel, and there's something I can't seem to work in there.

Granted, I'm relying on 30 year old memories from when I was working on microwave radios in the air force. But if memory serves me right, then a change of 3 db is double the power, and -3 db is half the power. And since the impedance is constant, it also means the voltage is either doubled or halved.

So let's assume the signal is scaled so that the (maximum A/D reading +1) corresponds to +7 dbm. Then half of that would be 512 or +4 dbm.

If you keep dividing that down, since there's only 10 bit's, you end up with a minimum of -23 dbm with an A/D input of 1.

And it appears that it would take a resolution of 16-bits to be able to get down to -40 dbm.



I think this applies to however you do it. Lookup, calculate, ...

ADDED: And any noise or offset voltages will Obliterate the low end.

But then, maybe I've got it all wrong? ??
<br>

I was always taught (having worked in the audo industry on digital mixin consoles, and having spent years designing synthesisers and samplers as a hobby) that the actual figure is around 6dB per bit, so 10 bits gives you 60dB, but in reality it's more like 4.5dB. I might be wrong but this is what I've always been told. Surely all you have to do is shift the levels?

[Ioannis]

I was always taught (having worked in the audo industry on digital mixin consoles, and having spent years designing synthesisers and samplers as a hobby) that the actual figure is around 6dB per bit, so 10 bits gives you 60dB, but in reality it's more like 4.5dB. I might be wrong but this is what I've always been told. Surely all you have to do is shift the levels?

Look at http://www.picbasic.co.uk/forum/show...1&postcount=68. That one was solved!

Ioannis

[Marin]

Hello!

I've try to get some bar from this and I've got problem as usual ;-)


So this is little code from me:
INCLUDE "LCDbar_INC.bas" ' Include the BARgraph routines


DEFINE LCD_DREG PORTB
DEFINE LCD_DBIT 4
DEFINE LCD_RSREG PORTB
DEFINE LCD_RSBIT 1
DEFINE LCD_EREG PORTB
DEFINE LCD_EBIT 0
DEFINE LCD_BITS 4
DEFINE LCD_LINES 2
DEFINE LCD_COMMANDUS 2000
DEFINE LCD_DATAUS 50



INPUT PORTA.0

i var word


LCDOUT $FE, 1 'clean screen

while PORTA.0 = 0
i = i+1
LCDOUT $FE,2,"Value = ",DEC i," "
' syntax- BARgraph Value, Row, Col, Width, Range, Style
@ BARgraph _Value, 2, 0, 16, 255, lines
Pause 100
wend


As You can see in picture I've got problem when compiling with LCDbar_INC.bas...and get'+s lot lines of syntax error in INCLUDE file......off course I didn't make anything to this file...just copy -> paste....


Do You know what couses this problem?

[Darrel Taylor]

' syntax- BARgraph Value, Row, Col, Width, Range, Style
@ BARgraph _Value, 2, 0, 16, 255, lines

_Value should be _i in this case.

The comments a little confusing at first, but once you figure it out, it just seems natural.
<br>

[Archangel]

Hi Marin,
To use Darrel's tidy little include files, you must place a copy of his file in the same directory as your code's file is in, and you must use MPASM as the assembler, not PM.
JS
Oh, and do they ever work sweet too!

[Marin]

OK!

Joe, is they any way to this be compiled in PM with some changes in .INCLUDE file?

[Ioannis]

If Darrel would make major changes it might!

But then again why would he? MPASM is much better assembler!

You still have your beloved compiler to write your code. Let Microchip do the job that knows better than anyone third.

Ioannis