Matrix Orbital LK204-25 and PicBasic

[Jųan]

Has anybody tried writing PB code to this LCD? I was previously using a 16x2 serial LCD and had no dramas but decided to get more space so I got the matrix orbital LK204-25. I have connected RB0 to pin 3 of the DB9 on the MO LCD and power through the I2C ports (MO). I have set the jumper connections to J0 and J2 (according to manual, it sets the baudrate to 9600). Then I am using:

serout portb.0,T9600[254,128,"hello world"]

but I get very funny characters.

Anyone shed some light or point me in the right direction with this MO LCD?

Thanks in advance

Juan

[badrad]

Not sure about your specific module, I just completed my project using the larger graphic displays GLC24064, and also experimented with the GLK12232. I had on a prior project worked with different larger displays - the Noritake VFDs and IMHO prefer the Noritakes over the MO. The MO interface to the display is quite slow and there are some features the interface (24064 anyways) lack such as handling a simple CR LF (the 24064 throws them away).

What is the command 128? 126 is for key auto-repeat on, and 118 is for bar-graph, but I didn't find anything for 128. Their documentation is horrible, and I had initial start up problems because of confusing sections.

From the development side, I had difficulties with the displays operating at 19200. when i dropped it down to 9600, my communication errors dropped.

I am just using the serout2 command thru my code.

portsetup con 84 '9600 baud non-inverted

serout2 serial1, portsetup, [$FE, $58]
serout2 serial1, portsetup, ["Hello World"]

By the way - did you connect using a 1K resistor between the pins?

However, since my PIC project is communicating primarily with a bunch of I2C devices, I am considering to connect to the MO via I2C instead in a later revision. But more likely in the later version I will scrap the MO and go back to Noritakes.

[Jųan]

Thanks for your reply badrad, yes I have connected 1k resistors between pins. I was using serout command, I will try serout2. 128 is the first location on the LCD (position zero). Does your graphic LCD have four jumper connections? On mine, they determine the baudrate. From the data sheet, I gather that j2 and j1 are in while the other two are out for 9600. Is that the same case with yours?

So far I havent found too much stuff on the net regarding PIC interface with these type of LCD's. Most people appear to use them for connecting to PC's etc.

Does anyone know where I could find a good article on interfacing MO LCD's and PIC's?

Juan

[badrad]

Hi Juan

BTW - are you using a MAX232 between the PIC and your display? You do know that your display will not operate at 5v rs232?

The baud rate on the GL displays are handled through the command set. $FE $39 $xx sets the baud rate. The default baud rate is 19200. I had initial problems with the displays baud rate 19200, it would also intermittenly drop characters, and I had to drop the baud rate down to 9600. Since the project had some tight deadlines, I did not spend the time to find out why the 19220 was a problem.

There were two setup jumpers on the board to setup the 4 pin header as I2C or RS232C. There were 4 solder pads that sets the RS232 port is +/- 12 or TTL level. The photo they show in their documentation does not reflect the revision I had, so I had to make a guess as to the correct pads. There are actually another 1/2 dozen solder pads through the board, so I did take a guess that the pads closest to the MAX232 would be the ones.

I am adding another point to the "why I hate MO displays" list. After burning 2 late nites trying to resolve an erratic display error (after a period of time, the display receives and displays text in slow motion), it turned out to be an occurence of how their stupid backlight timeout operates.

Anyways, now that this part of the project is complete, I will put the MO experience behind me, and I am ordering up several new displays from Noritake. Just as an aside - One of my earlier projects used a Noritake display. During yet another critical weekend I accidently reversed the polarity on my power supply and fried the Noritake display! I contacted the Noritake rep, and without a blink - they couriered a free replacement to the site where the display was needed. We installed and we got our demonstration working on-site. In my books, these reps went above and beyond helping out a developer.

I tried the MO display only because the power consumption is less as we need to use battery supply, but the Noritakes exceed these MO by leaps and bounds. So I am spending this coming week looking to beef up the battery supply to use the Noritakes.

As to threads on PIC to MO interface, I searched through the MO forum http://www.lcdforums.com/forums/ as well as the PICBASIC and several google searches, but not a thing. I need to work on the next function of the project which is to add graphics.

[Jųan]

I really liked how the MO display looked on the few pictures on the net. Thats why I got it. It was the only one that was available locally too while the other ones would take a couple of weeks.
The local supplier charged me $136.235USD for that. But thats what I get for living in the sticks. I wont be able to buy another one for a while, so I guess I will have to get used to this one. Yes I read that I have to use a Max232 to do the interfacing. Thanks for confirming though. I found a relatively good article regarding this stuff: http://hyper.sunjapan.com.cn/~hz/PIC/index.html

I will come up with a solution on how to use these efficiently and I will let you know. If there is a will, there is always a way!

Regards

Juan

[badrad]

Hi Juan
Ouch! $136USD for a basic text display...

Why not try using the I2C instead of RS232? If short distance isn't a factor, you won't need to buy another part, just add a couple of 4.7K resistors and assign 2 pins using the I2CWRITE commands. It looks pretty straightforward, and if only using text it should not be a problem. I read in the the MO forum that you cannot download fonts or graphics with I2C.

Good luck.