LK204-25 freezing after I2C write...

[mwhite76]

First, let me say if I can get this display working its beautiful Very excited to have some nice looking output for my projects.

The boot screen on my LCD shows LK204-25-WB-C74. My issue is the LK204-25 locks up after an I2C write...

What I've found is that after writing some amount of data to the display it freezes. Inserting delays between the I2COUT commands helps reduce the lockups but doesn't prevent it.

Power cycling the display has no effect. What does seem to work is powering the device off, removing the address jumpers J1 and J2, powering the device back on (effective giving it a new I2C address). I can then write to the new address or power it off, put the jumpers back and write to the old address. This works for some time and then it freezes up again. In either case I can never really write a full display of text before it stops working.

I assume its something in my code, but I'm not sure... I'm using 4.7k pullup resistors -- SDA and SCL lines are on pins 0 and 1 on my Basic Stamp.

Here's my code:

' {$STAMP BS2px}
' {$PBASIC 2.5}

SDA PIN 0 ' serial data line
SCL PIN 1 ' serial clock line

Main:
PAUSE 1000 ' wait a sec
I2COUT SDA, $5C, [$FE, 88]
PAUSE 100
I2COUT SDA, $5C, 0, [$08, "test1", $0A] ' this works
PAUSE 100
I2COUT SDA, $5C, 0, [$08, "test2", $0A] ' this is where I usually lock up
PAUSE 100
I2COUT SDA, $5C, 0, [$08, "test3", $0A]

I haven't tried writting to this device serially yet but I will.

Anyway... any insight or sample code anyone could share with me to get this working I'd sure appreachate it.

Thanks!
Matt

[Raquel]

Hello Matt,

Thank you for posting on the forum.

Can you please tell me the PCB rev# and the firmware version of your LK204-25? The PCB# should be on the board, the firmware version can be queried by connecting the module via RS232 or TTL and sending the command 254 / 54.

I am a little rusty on my basic stamp, but then if the first line ('test1') works, I see no reason for the other ones not to (since they are very much alike). Do you get to clear the screen with I2COUT SDA, $5C, [$FE, 88] ?

[mwhite76]

Hi Aurthor thanks for getting back to me on the LK204-25.

I rewired my breadboard i2c interface, changed batteries, and moved up to 22ga. wire. What ever I did in the mix seems to have fixed the problem -- I've been using the display for several days now without any issues.

Althougth... I noticed something querky with the displays autoscroll... I need to write to the end of the line 4 to get it to autoscroll. A simple LF (once I'm on line 4) doesn't scroll the text up. This leaves me with having to calcuate white spaces to the end of the line. This is probably working as designed... I just found it a bit odd that's all.

Anyway thanks for the response -- I think I'm all set now! Wonderful displays -- you can thank your friends over at Parallax for turning me on to your devices. =)

Matt

[Raquel]

Hi Matt,

I am glad that you have resolved your issues, and indeed thanks to Parallax for their support.