• We recently switched our forum platform. If you experience any issues please email support@crystalfontz.com

CFA635 Internal MB cabling - LCD Resets/Flickers

iambujo

New member
Hello -
I have been running a 635 connected to a Commell LV-670 for a while now. I have not been having issues with the LCD connected via a cable routing to one of the external USB ports.

I just got around to internally cabling the LCD to the Motherboard header for USB. Now when I power up the system (running Linux CentOS 4) the LCD screen and button pad backlight flickers like crazy, to what looks like maximum backlight and contrast, then dim, then back, at random. At the same time the 4 LEDs on the left side also flicker random colors. If I run my software in this state, it seems that communications are hosed between it and the display, buttons are unresponsive and my strings are not displayed (from what I can tell between the crazy flashing).

I would suspect this is an undercurrent or handshaking issue of some sort. NOTE - this happens as soon as the usb driver is loaded in the kernel at bootup, WAY before my app even starts. Any chance this sounds like a bad internal cable? I am positive I have the pinout right according to the documentation...

If anyone has any ideas of things to try I would really appreciate it! Here is a link to the LV-670 motherboard:
http://www.commell.com.tw/Support/SBC/LV-670(S).htm#Test

Thanks!
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.
 

iambujo

New member
I got the cable today, but unfortunately I got the same results. I also just tried a second LCD I have that works with both the internal and external USB ports on a Via motherboard with no success.

It seems the problem is just with the Commell 670 internal USB header connection. It briefly worked for me once tonight, then started scrolling again (looks like the contrast is maxed out and there is a rolling refresh to it)with the LEDs and button pad flicker moments later. At this point it either seems like a bad motheboard or some odd incompatibility with the motherboard (but only on the internal motherboard USB ports). I can't make any sense of out that, but hey, who knows...

I'll email the vendor I got it from and see what they think. By the way, I am running CentOS with a 2.6.17 kernel. Can you think of any reasons why the external port would work but the internal one would give me such odd results? Have you had any other customers with USB port compatibility issues?

Thanks
 

CF Tech

Administrator
Some USB headers have a jumper that can make them powered from Vsb (the computer's "always on +5v). If the LCD is connected to one of those headers, maybe try jumpering it for thre "normal" +5v, or moving the connection to a different header.

There is no good reason that the Vsb enabled USB header should not work, but it might be worth a try . . .
 
USB LCD Displays - Graphic and Character LCDs with a Keypad

iambujo

New member
Logic Supply got back to me, and have reproduced the problem. It seems the motherboard's internal USB header is only putting out 4.5 to 4.6 V, not the minimum 4.75 V that 635 LCD requires.

So, from the LCD's design stance, would there be any issues if I tapped +5V and GND from a power supply hdd power connector with a custom writing harness? Is there a cable available already to do this? Does anything have to happen to JP2 then?

Thanks so much for all the great support
 

CF Tech

Administrator
How interesting :) we bought 6 of the Logic Supply boxes for production testing, and made our own cables for them. I'll see if I can get CF Support to make you one. I am not sure which MB we have in our boxes though.

But in any case, it should not be a problem to bring +5v and GND from a HDD connector.
 

iambujo

New member
I am using a Commell LV-670 MB I bought from Logic Supply. If there is a cable option you could come up with, I would gladly give it a try. If not, I am comfortable making one myself at least for a one off test.

If I tap +5 from an HDD connector, with the 635 design would I be better off getting ground from the HDD connector as well, or from the USB header? Would either way void any Crystalfontz warranties? Before hooking up, I'll put a volt meter on the HDD connector to make sure the values are within 4.75 and 5.25 per the 635 manual.

I won't be able to test anythign for about a week, I am heading out of town.

Thanks again!
 

iambujo

New member
Ok, I tapped +5 and Ground from a hard drive power supply connector. Things work great now. I am sure I can come up with a valid wiring harness for this, but if you know of a pre-made harness that will work here, I'd love to know.

Thanks
 

luciano11

New member
Hey guys ---

I am using 631s installed in Uniwide 1322 and 1522 Servers and I have seen a couple of similar issues. The systems are running linux.

There are two different issues that have come up:

1) The LCD will stop printing any strings that have been issued to it (and will stay blank), but it will continue to pass button press information.

2) The LCD will at random disconnect (as viewed through dmesg) and then reconnect randomly (on the order of several seconds or minutes later) and be re-detected by the ftdi/usbserial drivers (again viewed through dmesg). After the reconnection the LCD is not responsive to any data set/gets (the backlight is on but the screen is blank), and does not pass on button press information.

I had attributed both scenarios to 'loose' connections on the internal motherboard USB pins. However I am wondering now if scenario #1 a voltage issue. I checked the FTDI page for the FT232BL USB uart chip and I see that it can still operate down to 4.35V ... but the LCD controller minimum operation is at 4.75V. I *think* this would partially explain scenario 1. It would be helpful to know the operating voltages for the microcontroller.....

I still think that scenario #2 is from loose pins (the servers using the LCDs are in racks with 7+ other machines in the rack, and there is a good bit of vibration in the cases from the fans).

Anyone have any thoughts on this?
 

CF Tech

Administrator
Let's get one of the WRPWRY24 cables installed in a system and see if it fixes any troubles.

The module should not disconnect/reconnect/stop responding under any normal circumstances.
 
Top