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LK204-25 Display Locks Up and Freezes
Posted: Thu Mar 31, 2005 11:44 am
by jason
Hello,
I've got about 20 LK204-25 displays that I know, over time, the couple that I've tried are locking up. The display will freeze with the last information that was sent to it.
-I'm using a Philips Micro LPC935 to drive the display.
-I'm using the I2C.
-Not using the GPO's.
....However, the Micro continues to work and I am able to continue without a problem except that the display stops updating.
I've checked to make sure that the data transmission is still alright going to the LCD display and it is.
Could this be a grounding issue?
Any advice would be great!
Thanks,
Jason
Posted: Thu Mar 31, 2005 12:09 pm
by Miles
Thank you for the post Jason.
Can you tell me what type of length is involved from controller to the display?
LK204-25 Display Locks Up and Freezes
Posted: Thu Mar 31, 2005 12:33 pm
by jason
Miles,
I would say it's about 6 to 8 inches from the controller to the display.
Posted: Thu Mar 31, 2005 1:08 pm
by Miles
Is the lock up random or does it appear within a specific time frame?
LK204-25 Display Locks Up and Freezes
Posted: Thu Mar 31, 2005 1:10 pm
by jason
It locks up random....anywhere from 2 minutes to at least 1 hour.
Posted: Thu Mar 31, 2005 1:15 pm
by Miles
What type of cable are you using to connect your controller with the displays?
Posted: Thu Mar 31, 2005 1:38 pm
by jason
I'm using a 4 pin ribbon connector, in which the whole package and wiring is done within a grounded sealed metal box.
Posted: Thu Mar 31, 2005 1:51 pm
by Miles
Is the display's bezel contacting the metal enclosure??
Posted: Thu Mar 31, 2005 1:57 pm
by jason
Yes it is.
I also have a ground wire attached to the screw that mounts the display to the enclosure.
Posted: Thu Mar 31, 2005 2:04 pm
by Miles
Sounds perfect!! What type of pull up resistors are you using for SCL and SDA??
Posted: Fri Apr 01, 2005 7:36 am
by jason
Miles,
We have 10k ohm 1/4watt pull-up resistors on SCL and SDA.
I was wondering if it could be noise on the power line or a drop in voltage?
Posted: Fri Apr 01, 2005 7:43 am
by Miles
A significant drop in voltage may cause a lose of communication...Depending on the hardware involved, I have seen instances were 2.5 Volts on the SCL line will cause havoc, however in other causes it works fine...
Have you played with resistor values...strengthen or weaken the pull ups will affect communication...
Posted: Fri Apr 01, 2005 7:46 am
by jason
No I have not changed the Resistor Values.
Do you think it could be a Power issue?
Posted: Fri Apr 01, 2005 7:56 am
by Miles
It is very possible...do you have a way to monitor this...?
Posted: Fri Apr 01, 2005 8:09 am
by jason
Yes,
I've got a scope that I can look at the voltage on.