Libray for character LCD modules (Busy flag/random pins)

Plons · Posted: Sat Jul 12, 2008 3:14 pm Post subject:

Very good. I tried the code you posted, Luciano. Except for the MCU, since I use a M168.
The result: in the picture

So what is going on ? When I do a manual reset, the result is OK. When I come from a power-down situation, it doesn't.

I have to sort that out. It has to do with the OLED. The AVR generates (using PWM) the contrast voltage. When that voltage is (too) low, something goes wrong in the initialization.

What I can confirm now: Luciano is right, the "Config lcdpin etc"-statement is not needed to make LUC_lcd4busy.lib work. But for the OLED I do need it. I will sort it out and let you know.

Thanks for the support !

Nard

Plons · Posted: Sat Jul 12, 2008 4:05 pm Post subject:

This is a tough one.
I modified the hardware to ensure that the Contrastvoltage is 5V at power on. It didn't do a thing .... Sad

Added wait-statements in several places ... just to sort out what would cure the effect: no deal ....

But: a re-init of the OLED does the trick (just a code-fragment shown here, the rest is as shown in previous posts))

Plons · Posted: Sun Jul 13, 2008 12:51 am Post subject:

I removed the pull-downs on E and R/W ....
Supply the board from a lab-supply ...
Increased delays in luciano's lib .....
Updated Bascom to 1.11.9.2 ...

... and learned a bit more: that Config lcdpin in Options - Compiler - LCD is not as harmless as I (and maybe you ... ) thought: when not overruled by a Config lcdpin in the program, it still sets the DDR-bits as dictated by the Options - Compiler - LCD - setting. Yikes. Never realised that ....
I discovered it because the OLED contrast should be fine even when the PWM-output-pin is configured as input. But the OLED was very dim. (not in the pictures btw)

So: I am stuck. Puzzled. Can fix it with that extra Gosub _init_lcd, but would like to know the WHY ...

I have some other LCD's, but need to make a different cable for those. Sounds like a sundaymorning thingie.

Cheers !

Nard

Luciano · Joined: 29 Nov 2004 Posts: 3149 Location: Italy

Hi Nard,

The routine "_Init_LCD" present in LUC_lcd4busy.lib will set the data
direction of the used pins. The routine _Init_LCD is called when you
call the first LCD command in your code. (In my sample, Cursor Off Noblink).
The routine _Init_LCD present in LUC_lcd4busy.lib overrides the settings
present in the Bascom Options-Compiler-LCD whatever they are.

At power-up, during the hardware initialization performed by the Bascom
initialization code, the data direction of the pins selected from
"Options/Compiler/LCD" is set. To avoid that, just select the radio
button "Data mode = bus". By doing that, no data direction register will
be changed by the Bascom initialization code to support the LCD so that
you will save some program space. If you go back to the Bascom internal
LCD routines, then you must remember to set "Data mode = pin".
Again, the routine _Init_LCD present in LUC_lcd4busy.lib overrides the
settings present in the Bascom "Options/Compiler/LCD" whatever they are.

Best regards,

Luciano

Plons · Posted: Sun Jul 13, 2008 4:25 pm Post subject:

Finally, finally ....

I had an original HD44780 display, 16*2, and that showed the same problem. And that made no sense. The OLED has a clone of the 44780, so I could imagine some incompatibility there. But this old display should work !
I took another AVR-board, and tested with *several* displays. They all worked fine.

So what is wrong with the OLED-controllerboard ?? It's a straight forward design, in which I had connected the lower datalines D0 - D3 to ground.
And that caused this weird behaviour !!

Mystery solved. Thanks for your support, Luciano. Since PM is disabled on this forum, would you pls. contact me on "2 times my nickname here, no spaces, no capitals, the curl, and then gmail etc" Not to ask you for more support, just want to send you a present.

Nard

Luciano · Joined: 29 Nov 2004 Posts: 3149 Location: Italy

Hi Nard,

You're welcome!
Your "thank you" was more than enough.

Best regards,

Luciano

enniom · Joined: 20 Oct 2009 Posts: 537

Luciano,

After all this time, lcd_busy is still one of the most innovative solutions for working with LCD's. Congratulations.

If I wanted to use lcd_busy to drive a 40*4, would that be as simple as toggling the E2 line separately via a program-based PORT/PIN Set/Reset just prior to sending the Lcd "Text" command - or - would that interfere with the E toggle built into the lcd_busy.lib?

If the approach above is not possible, how difficult would it be to modify lcd_busy.lib to include the E2 toggle function?

Grazie.
Ennio

Luciano · Joined: 29 Nov 2004 Posts: 3149 Location: Italy

Hi Ennio,

it should be quite simple to write a library which checks the state of the busy flag of an
LCD with two HD44780 controllers (4x40 LCD). See the original Bascom libraries "Lcd4e2.lib"
and "lcd4busy.lib".

If you have questions about how to do that, please start a new thread in an appropriate section
of the forum.

* * *

Here is a sample how to use the Bascom library "Lcd4e2.lib".
http://www.mcselec.com/index2.php?option=com_forum&Itemid=59&page=viewtopic&p=31687#31687
(Busy flag not used).

Best regards,

Luciano

Neill · Joined: 08 Dec 2008 Posts: 50

Thanks so much Luciano for your library. It has helped me very much.

Writing to a 4 line by 20 char display is now very fast and means that I can have real time events happening exactly when I need them to, every 50mS and I don't have to worry about how long it is taking to update the LCD.

Grazie,
Neill

Aleksandr · Joined: 29 Jul 2010 Posts: 15 Location: Russian Federation

Hi, Luciano!
For me does not work "LUC_lcd4busy.lib".
In what a problem?
My code:

Ross_ValuSoft · Posted: Mon Aug 02, 2010 11:37 am Post subject:

Do you realise that you are trying to write a 20 character string onto a 16 character screen?

Also ... see if allowing the screen to clear first helps.

Luciano · Joined: 29 Nov 2004 Posts: 3149 Location: Italy

Hi,

Before testing your program, make sure you disconnect the ISP programmer first.
(The ISP programmer uses the pin PB3).

Best regards,

Luciano

Aleksandr · Joined: 29 Jul 2010 Posts: 15 Location: Russian Federation

Thanks, Ross_ValuSoft. Why I have not guessed?)))
Luciano, I certainly disconnect isp prrogrammer.

Thanks all for the help

Frankeman · Joined: 11 Aug 2004 Posts: 948 Location: the Netherlands

Hi,

Write a little test program that toggles every used pin which is connected the the LCD.
Do this pin by pin and measure al the connections on the display.
This way you are sure that every connection is correct and a short circuit can be found.

Aleksandr · Joined: 29 Jul 2010 Posts: 15 Location: Russian Federation

Frankeman, i used multimeter for testing connection to LCD.
All connections is good. Changed controllers, without result.
There are at someone else ideas? Idea

May be "LUC_lcd4busy.lib" not for all kontrollers?
Mr.Luciano! On what controllers you have checked up "LUC_lcd4busy.lib"?

Best regards