Serial LCD problem

[mind]

Hi guys

I am posting this here, after going nuts trying to figure it out myself (repeatedly) and much googling with no luck.

I have a PIC16F88 and a 2 x 16 serial LCD using a ST7036 Sitronix controller. The controller is HD44780 compatible. The display remains blank (ie: nothing happens).

The code is as follows:

    INCLUDE "modedefs.bas"
    DEFINE OSC 4
    DEFINE CHAR_PACING 1000
@   DEVICE  PIC16F88, INTRC_OSC_CLKOUT, WDT_OFF, PWRT_ON, BOD_OFF, MCLR_OFF, PROTECT_OFF
    osccon = %01101110
    sspcon = %00110001
    trisb  = %00000000
    disable interrupt
    pause 500   ' wait for LCD to startup
    
    LCD_ChipSelect var portb.0
    LCD_CommandLow VAR portb.1
    LCD_SerialIn VAR portb.2
    LCD_Clock VAR portb.4

    Symbol LCDMode = N1200
    
    HIGH LCD_ChipSelect                          '  select LCD on SPI bus
    LOW LCD_CommandLow                       ' select command mode
    Serout LCD_SerialIn, LCDMode, [$38]     ' function set
    pause 50
    Serout LCD_SerialIn, LCDMode, [$39]     ' function set
    pause 50
    Serout LCD_SerialIn, LCDMode, [$14]     ' bias
    pause 50
    Serout LCD_SerialIn, LCDMode, [$78]     ' contrast set
    pause 50
    Serout LCD_SerialIn, LCDMode, [$5E]     ' contrast control
    pause 50
    Serout LCD_SerialIn, LCDMode, [$6E]     ' follower control
    pause 200

    Serout LCD_SerialIn, LCDMode, [$0C]     ' display on
    pause 50
    Serout LCD_SerialIn, LCDMode, [$01]     ' clear display
    pause 50
    Serout LCD_SerialIn, LCDMode, [$06]     ' entry mode right
    pause 50

    HIGH LCD_CommandLow   ' data mode
    
loop:
    Serout LCD_SerialIn, LCDMode, ["Hello world"]
    Pause 500	' Wait .5 second
    Goto loop	' Do it forever

So, since this is my first ever LCD project, I have probably made a bunch of assumptions which have gotten me into trouble. Any criticism or pointers would be much appreciated.

Best regards
Richard

[Dwayne]

You need to send a DEC val of 13 to turn on the LCD.
From there, you can send ascii data.

I am not familiar with your "Serial LCD", and am not sure how it is set up to communicate. But it will need the DEC value of 13 before it will turn on.

Psuedo Code

Command pin = on
serout pin,13
Command pin = off
serout pin,"Hello World"
end

Dwayne

[mind]

Hi there

Well, I have the line:
Serout LCD_SerialIn, LCDMode, [$0C] ' display on

Since the spec defines it as : 00001DCB
where:
D = display on
C = cursor on
B = Cursor blink on

So, $0C = 0000 1100 = display on, no cursor, no blink

Your suggestion of needing to pass it "13" is 1101, ie: display on, no cursor, blink on.

Any other thoughts on what to look for, would be appreciated !

-Bye
-Richard
ps: yes, I did try your suggestion too ! ... no luck

[Dwayne]

Then I would check your contrast....Put a 10k center tap pot with contrast pin of LCD in the middle, and connect the ends of the pot to +/-. ADjust pot until you see black squares...

If you cannot see them with a command 13, then I would start questioning your LCD, whether it is good or not.

When you say "Serial" LCD, you are talking about ONLY 3 wires going to it, right???? 1. - data 2- Positive 3 - ground.

If this is so, you may have to check your manual to the SERIAL LCD, and see how to "Turn it on".

One other point... SCOPE your pic chip!!! make sure you can see your data being sent !

Dwayne

[mind]

Hi Dwayne

Serial LCD is only a little more complicated
Data, clock, Vdd, Vss, command select pin (command/data mode), chip select pin (so multiple chips can share the SPI interface).

So, yes, contrast is done in software. The manual says exactly what I quoted in my previous post about which bits to send to turn it on.

And I wish I did have a scope... Time to schmoose some of my EE friends who do have scopes !

It is possible that I am not outputting clock signal or something (but I checked with a LED, and it does light up!).

Best regards
Richard

[NavMicroSystems]

Mind,

I have never used one of these displays,
but a quick glance at the datasheet makes me feel the serial interface is I2C or SPI, not asynchronous.

So it won't work using SEROUT.

pressuming you have the controller configured and wired up correctly
use SHIFTOUT or I2CWRITE.
(Dependend on the controllers config)

[mind]

Hi

Yes, it is meant to be an SPI interface. I had assumed SPI = serial, and therefore I should use SEROUT.

I have made the changes, but still no luck

Best regards
Richard

[NavMicroSystems]

Hi

Yes, it is meant to be an SPI interface. I had assumed SPI = serial, and therefore I should use SEROUT.

I have made the changes, but still no luck

Best regards
Richard

Richard,

could you post the changed code?

[Dwayne]

Hello Mind,

Mind>>Serial LCD is only a little more complicated
Data, clock, Vdd, Vss, command select pin (command/data mode), chip select pin (so multiple chips can share the SPI interface).<<

I have used both SERIAL, 4 bit and 8 bit buss LCD's. Complicated? I have designed my own Serial controlled LCD's, used on my Instrument panel of my Experiemental. <g>. Granted, there are many things I do not know. But I can only give you generic data on a controller that you said was compatible to the HD44780. How that data is fed to the LCD is up to the person who designed it.

Ralph I see responded to you... He is top notch...Same with STeve, Melanie, Bruce, and Darrel. They work with it on a daily basis for their work.

Mind>>So, yes, contrast is done in software. The manual says exactly what I quoted in my previous post about which bits to send to turn it on.

And I wish I did have a scope... Time to schmoose some of my EE friends who do have scopes !<<

That can help out a lot! It can get rid of the "Gotcha" and things that SHOULD be working... and you find out they are not working.

Dwayne

[faital]

Hi, This post is very informative, however I would like some specific information. If someone can help me then please send me a private message. Best Regards,

faital - If your post is genuine then somebody just might PM you (unlikely with your request), but if not, rest happy that your thinly veiled website adverts didn't even last 20 minutes, probably only noticed by one or two people (your bad luck one of them was me!) and took far less time to kill than you took to create! Melanie

[livin4th]

i have read the posts made in the thread and i am trying ti get the same display to start using SPI interface.after successfully interfacing the display to board and sending the correct data sequence to the display from the MOSI pin(checked in scope), the display is still dead.I am confused as to what might be the problem during initialization.

the data i sent from spi MOSI is using standard SPI function for the board SPI_I2S_SendData(SPI2, byte);

the byte is transmitted successfully.but the lcd doesnt start.

in the LCD part of the code is it necessary to do any coding prior to the initialization like addressing registers and all?i just started sending commands through MOSI to SI pin of display.should i do some coding for shifting the registers in display for data? am i doing something wrong?