LCD with Marlin displays garbage

I built an LCD control panel for my prusa, sourcing my own parts, but generally following the instructions for the panelolu over at thingiverse. It worked great except that periodically the display would start to display garbage characters. You could still make out what was intended to be on screen, but it would be interspersed with strange looking characters. Sometimes the display would go totally blank.

This happened very rarely, and once Iearned that you can reinit the display by removing and reinserting the SD card, I was OK with it.

So now, I built a new printer based on wired1's OB1 design. I moved the control panel over to the new printer, but it is physically further from the RAMPS, so I had to make a new wiring harness. Rather than do a lot of soldering, I purchased 24 inch pre-crimped wires from Pololu and made my own custom cables that are intact from end to end. No soldering except on the 5volt and Ground wires that needed to be fanned out inside the control panel housing.

The panel works fine, but now I have a MUCH higher occurrence of the garbage. I had thought that being a little more careful in building the wiring harness would solve the problem for me, but it didn't. I'm thinking the culprit here is the length of the wire and the proximity to other wires and motor coils. What's weird is that the panel is just fine unless I reach into the printer - to change filament, tweeze away some ooze, or whatever. Not every time, but enough that it's bothersome.

I'm thinking of wrapping the wires between the panel and the RAMPS with some kind of shielding, but not being an electrical engineer, I don't know that I'm not just taking shots in the dark. Does anybody know/think this might help, or perhaps have other suggestions.

Thanks

I had quite the same issue on my Prusa. In my case also the sd card connection broke from time to time and my printer startet to draw fancy stuff.
In my case the lcd as well as the sd card were connected through an unshielded flat cable to my Gen7.
I've switched to a shielded cable and now the problems are gone. So it was definitely a noise issue in my case.

Thanks. Did you build your own cables from shielded stock, or did you shield the cable you already had? I'm trying to find a good source of shielded wraps, but they are a bit pricey. I don't want to drop too much money only to find that it does't help.

I've just bought a shielded one

Try scrubbing the soldered connections with some rubbing alcohol on a tooth brush (while it is turned off) and then let it dry before plugging it in. It is possible that you have some soldering flux or stray beads of solder causing noise between the pins.

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Did you ever get this resolved? I'm having a similar problem with Panelolu and Sanguinololu 1.3a in a MendelMax. It usually fritzes out when the bed heater relay kicks on or I get close to the printer..

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ΜΟΛΩΝ ΛΑΒΕ

Never solved, but I have plans that I hope will help. Mine has improved somewhat. It happens much less often, and I've been trying to ground myself every time I reach into the printer.

Anyway, I am planning on moving where I have my RAMPS mounted so that the wires between the LCD and the RAMPS are MUCH shorter. Right now they're 24 inches long. I' hoping to get them down to 6-8 inches. I'm also trying to figure out some way to shield them. I've been looking for wire mesh that I can wrap around the wires and then either tape or shrink wrap over.

I've also been thinking I could use a short length of STP ethernet cable just for the LCD signals.

I've got 3 feet of ribbon cable between the LCD and the Sanguinololu.. I spoke with the guys at Think3DPrint3D and they think it may be a bad LCD module so they are replacing it. I'm a little skeptical but I'll try it. If that doesn't work, I'll buy some shielded cable from Digi-Key and make a new cable. It's bad enough that I don't dare and try to print from the LCD module's SD card for fear of wasting time and filament when it crashes. Static electricity is bad this winter for some reason.. If I even touch the printer when it's hooked to Repetier and printing, I'm afraid of it reseting. When it happens, it's ugly and requires powering off, unpluging the USB cable and re-starting Repetier...

Not having the Mendelmax chassis grounded (most of the aluminum pieces are electrically isolated) and not having the the power supply grounded to the Sanguino is a little counter-intuitive to me.

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ΜΟΛΩΝ ΛΑΒΕ

3 feet of unshielded ribbon cable between the electronics and the lcd/sd is TOO LONG for a stable connection. I'm a little surprised they think it's not.... Holy cow (*puts "think3dprint3d" on $hitlist)... Now if you are LCD only (no SD), then you may be ok with that length.

For a stable SD connection to your electonics with unshielded cable, you want a MAX of 1.5 feet (@457mm).

The newer lcd/sd kits I've been seeing have even shorter cables, at 9"(228mm) (I'm assuming due to connection issues perhaps even at 1.5feet).

As was mentioned earlier, go shielded if you can, otherwise keep your ribbons short when SD cards are involved.

And always use a quality, heavy, shielded USB cable for your PC connection.

Edited 2 time(s). Last edit at 02/28/2013 11:43PM by xclusive585.

So far, the problem only seems to be with the display freaking out. I can read and write to the SD card through a host even when the display is not working. I hope it is only the display being defective but I'm ready to shorten the cable if I need to...

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That's my experience as well. The SD card works fine, but the display freaks out. Did you know you can reset the display by either removing or re-inserting the card. So it seems the firmware is still functioning correctly, it just loses sync with the LCD.

McMaster sells a shielding wrap for post installation. It's about $8/foot, but I only need a few feet. Maybe that's the easiest way to go. Alternatively, as I've said, I can scavenge a short CAT5 STP ethernet cable and replace the LCD connections with it, but that would require me to do my own crimping and I wouldn't want to in any way compromise the cable.

jbernardis Wrote:
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> That's my experience as well. The SD card works
> fine, but the display freaks out. Did you know
> you can reset the display by either removing or
> re-inserting the card. So it seems the firmware
> is still functioning correctly, it just loses sync
> with the LCD.

It doesn't work that way for me. Once the display fritzes out, the only fix is the reset button on the display.

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I have been having this problem a lot lately. Same symptoms and removing and inserting SD card will clear it sometimes but cannot do this while printing.
I had a longer cable attached and it was really bad. Went back to the shorter version and better but can never finish a print with display remaining readable.
What type of shielded cables are you guys running? Where is the shield ground being connected?

Would a round shielded bundle be better or worse ?

I seemed to have solve my garbage on the display problem. 10 hour print and started another without any issues. Yea!

My solution.
1. Use the short cables ~ 12"
2. Make sure end plugged into ramps ihsaa cables exiting away from board.
3. Make sure no other wires are near the ribbon cables.

Definitely root cause is noise and shielded cables may be the best solution.

Update. 4-5 hours into this and many print starts from SD and straight from pronterface. LCD working flawlessly.

Edited 1 time(s). Last edit at 03/02/2013 12:56PM by Spk64.

Using Panelolu with Sanguinololu 1.3. All is well except files on the sd are displayed as folders rather than files. I too get the garbage display but I think my ribbon cable is too long as well as unshielded. Any thoughts on what I did wrong with the sd reader?

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Often in error, but rarely in doubt.

PJMoore Wrote:
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> Using Panelolu with Sanguinololu 1.3. All is well
> except files on the sd are displayed as folders
> rather than files. I too get the garbage display
> but I think my ribbon cable is too long as well as
> unshielded. Any thoughts on what I did wrong with
> the sd reader?


I had this problem too and I think it was related to the other display problems (noise on the connecting cable). Are you uploading to the SD card from the Panelolu or from a card reader? I wound up shortening the cable to about 18" and wrapped it with aluminum foil and packing tape. I carefully soldered a wire to the homemade shielding on one end and attached it to the frame. This pretty much cleared up all of my Panelolu problems. Check out the attached picture.

I've since moved on to a touch screen display however but it's a work in progress.

Edited 1 time(s). Last edit at 03/18/2013 09:52PM by Knimrod.

I load the gcodes to the microSD on my WinXP SP3 PC. The folks at Think3DPrint3D suggest I use a plain Sandisk SD, not an SDHC, and never a Kingston. We shall see.

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Often in error, but rarely in doubt.

sandisk supports spi. you can slow down the spi speed and it will make cross talk a lot less, however the wire still acts like an attenna for other noise such as stepper motors, power switching. and the slew delay from the capacitance can cause the miso or mosi to be out of phase causing corruption. i don't know what the official length is but i have issues over 12inch when using sd cards and a long connector. only have had good luck by slowing down spi for sd. max frequency works reliably is 4mhz.

just had same problem course switched my low current steppers to standart and i gave it a try and wrapd around a copper foil and yay it worked. didn´t belive in it first but desperate times demands desperate meashures. thanx

I have had the same problem with my printer, an OrdBot. I am using Arduino Mega 2560/ Ramps 1.4 and a Reprap LCD screen.
I rapped the ribbon cable with foil. It improved it but did not entirely eliminate the problem. Recently however I have printed an LCD case and the screen has not broken up since.

Another problem was stopping mid print and I found that was the USB lead. I changed it for one with better screening.

Hi,
I also have the same issues.

My LCD screen displays square boxes.

I am using this for connecting LCD to RAMPS.

I will try using RJ45 LAN cable & see.

-Prashant.

Edited 1 time(s). Last edit at 02/07/2015 03:30PM by prashantdshinde.

I have this same issue, and am also wondering if it has anything to do with the fact that I sometimes get a static shock either from the aluminum heatbed or from the power supply case. When the characters get scrambled it doesn't seem to mess with the gcode feed at all, so the print keeps going but again the display is unusable until I click the rotary wheel to update the entire grid. Do you think this is from the static or from unshielded cables? (The end of the LCD cables on the RAMPS are about 10mm from one stepper cable)

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Master Tinkerer