LCD BARgraphs

[Ioannis]

Yes Alain, MCU is 16F877, but this is minor.

Do you mean that with OPTION_REG=$81 does not work also at your test?

I have not the board with me at work now. I will test it late today.

Ioannis

[Acetronics2]

I have an old 877 here...

I'll breaboard it ...

We'll see !!!

Alain

[Acetronics2]

Hi, Ioannis

YOUR code has passed the Breadboard test ...

Works as expected ... ( little flash when PORTB.0 tied to ground )

Alain

[Darrel Taylor]

Looking at the PICDEM2+ schematic some more, it seems that there might be a conflict with PORTB.0

<img src=http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1794&stc=1&d=118289364 1>

With J6 installed (has to be for the LED on PORTB.2), the LED on PORTB.0 may not allow the voltage to rise far enough to register a HIGH level.
<br>

[Sean_Goddard]

I joined in this quite late, but on the original bargraph code posted by Darrel (and also the interrupt code posted elsewhere) I have one thing to say....WOW Darrel. GENIUS.. BOTH of these snippets have saved me hours of work on a project I'm working on.

I needed to poll an array of front panel switches every few milliseconds AND service a bargraph update AND change the frequency of a HPWM signal all at set times, I was in the process of writing an RTOS for the PIC to allow me to use queued commands executed on a priority/time basis, then these two pieces of code went live.

OK, you killed my six months of work on the RTOS, but I'm not complaining. Everytime I see a new posting by you I just KNOW it's gonna be soething that makes my life that little bit easier.

A huge thanks and keep up the excellent work.

[Darrel Taylor]

That's Great Sean!

Always nice to know it's not going to waste.

Hope it makes you money, or
Impresses the boss, or
Get's you an A+ on the project, or
simply presserves the hair, so it can fall out naturally later.

Best regards,

[Darrel Taylor]

Ioannis,

Just in case you're still thinking, It can't be that (Post #89) because this works ...

while portb.0=1
wend
high led1

If you look at the PORTB.0 diagram. You can see that it uses a TTL input buffer when reading PORTB as digital inputs. So, the High and Low voltage levels are 2.0V and 0.8V.

With the circuit on the PICDEM2+ you'll get around 2.25V with the switch open (depending on the forward voltage of the LED). So it works fine with the digital Inputs.

<img src=http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1800&stc=1&d=118290623 7>

But the signal for the INT interrupt, goes thru a Schmitt Trigger. And it's levels are .8VDD (4V) High, and .2VDD(1V)Low.

The circuits on PORTB.0 of the PICDEM2+ don't produce enough voltage to trigger the interrupt. (when the LED's are engaged)

HTH

[Ioannis]

Darrel, your suspicion of PICDEM2+ were confirmed! Damn, so many ours wasted over a stupid LED!

Thanks for the help guys!

Finally I decided to use the hardware direction about the log conversion to bargraph display. Faster, cleaner, wide dynamic, expensive!

Thanks again.

Ioannis