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Author Topic: Working LCD goes blank  (Read 4655 times)
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Manchester (England England)
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I added a 0.1uF ceramic capacitor across the +/- to eliminate noise from the PS
I would use a bit more and add a 100uF cap across the supply as well.
Is the blanking related to any relay activation?
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I'll add another cap tomorrow since I don't have any at home right now...

What is strange is that everything works fine, relays activate and deactivate as the should, PWM outputs work and LCD..: but then it just goes blank and everything else keeps working like a charm, I can't seem to find the source¿?

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The other thing that springs to mind is an intermittent connection to the power or ground to the LCD.
Have you tried waggling them and seeing if you can provoke the fault?
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If so should I still add another diode?
That shouldn't be necessary.

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I added ... resitance to the LCD backlight LED
How much resistance?

How about the other two questions in reply #2?


Don

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I added a 100ohm resistor in series, I only had that or a 50K...

From reply #2
I posted the code but dont have a schematic I posted pin connections, if you have any questions I'll be glad to tell you how about the wiring...

Tonight I'll try the hello world test and see if it stays o blanks out, maybe I can locate the problem that way!
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From reply #2 ...
No. These answers are in response to Reply #1.

Note that each reply has a specific number, your original post does not count.


Don

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I loaded the example code from the LCD library (Hello World), and it ticks no problem at all, which makes me think if Im demanding too much current, but its still strange that it runs for 2-3mins no problem and then blanks the screen??

I think im gonna remove the power to the backled and see if it helps... Maybe add another 5v PS to supplement the demand?
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Ok, I measured the voltage when it faults and goes blank and 5v remained, they didnt even budge... I also cranked up the PS to 15v no load, plugged in the circuit and dropped to 14.3v when, I tested with only one relay working and the voltage drops to 13.4v when the relay is activated... Could this be the source of the problem, ? Im really running out of ideas, should I add a secondary 5v supply?

The processors from the LCD display do not get hot at all, before or after going blank...
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Im going to add a couple of capacitors today, I'll stop by the store after work... Hopefully it will solve the problem!
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I loaded the example code from the LCD library (Hello World),I loaded the example code from the LCD library (Hello World), and it ticks no problem at all, which makes me think if Im demanding too much current, but its still strange that it runs for 2-3mins no problem and then blanks the screen??  which makes me think if Im demanding too much current, but its still strange that it runs for 2-3mins no problem and then blanks the screen??
You will have to translate this a bit for me, I live on the other side of the Atlantic.

"and it ticks no problem at all"  I interpret this to mean that the display works properly, even after 2-3 minutes.

"but its still strange that it runs for 2-3mins no problem and then blanks the screen"  I interpret this to mean that it doesn't work properly after 2-3 minutes.

So ... Do both of these statements refer to the current 'Hello, world!' display or does the second refer only to the display that accompanies the relays?


Don
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Hi Don,

Sorry for the mixup. First statement meant that the hello world example worked with no problem at all erin after 10minutes. Second statement was aimed at the complete system with whole code and fully functional (relays, transistors, RTC, LCD).

Given that the example works, I would think everything is hooked up ok, and other hardware too since it works without the display. But everything together creates the fault...
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Given that the example works, I would think everything is hooked up ok, and other hardware too since it works without the display. But everything together creates the fault...
I had a similar fault when I was using an LCD shield together with a servo and powering my Uno with USB power.  If I split power so the servo was powered by a separate power supply (and connecting the two grounds), it worked well.

So as I delve into motors and servos, I now have two breadboards, one of which whose power rails are wired from the Arduino, and the other I have a separate power supply (either 5v USB phone charger or wall plug to 2.1mm power connector).  When I was buying the secondary power supply, I thought it was the model where I could switch each side to 0, 3.3, or 5 volts, so that I could use just one breadboard, and have Arduino power on one rail, and external power on another.
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I'll give it a try today! I'll power up the relays with a different PS! I'll also add the capacitors to eliminate any noise from the supplies
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Ok so i hooked up the secondary PS for the relays and unplugged the backlighand now it takes it about 10m to fail and go blank... I also added a constant LCD.clear(); which is constantly refreshing the screen, after aprOx 10m it fails you can see a lot of weird letter around te screen and then comes back like if nothing happened after several minutes...

Right now the arduino is powering the LCD (no backlight) 3PWMs and 4 digital outputs, I believe it Gould be able to handle this no problem so who knows maybe I have a faulty short somewhere?
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knows maybe I have a faulty short somewhere?
You might.
Is the arduino still running when the display blanks out? Get the on board LED to flash each time through the loop() and see if it still flashes when the display fails.
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