RGB LCD Positive Backlight 16x2

by tritonesub on Sun Mar 17, 2013 9:04 pm

Hi, I have purchased the RGB LCD Positive Backlight 16x2.
The backlight seems to work ok but I can only faintly (sometimes) see the first line of "blocks" when connected to the pot.
After connecting the data pins to GPIO I cannot see the first row of "blocks" at all. I metered the pot and it seems to work fine giving 0-10k. I have tried connecting direct to the T-Cobbler, through the MCP23017 and with and without PWM for the backlight RGB control. I have tested the data pins on each setup with an LED to make sure they are working correctly.

I will upload pictures in the current configuration (MCP23017 and green backlight to ground).

Thanks,

Steve

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Re: RGB LCD Positive Backlight 16x2

by adafruit_support_bill on Mon Mar 18, 2013 5:00 am

Can't really tell where all those wires in the photo are going. Can you post one that shows both the display and the cobbler so we can see how everything is connected.
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Re: RGB LCD Positive Backlight 16x2

by tritonesub on Mon Mar 18, 2013 10:16 pm

The attachment image.jpg is no longer available


To simplify, I removed the data pins. I have the backlight powering from the PWM breakout and only the green led grounded. I have the power to 5v and pin 3 is to the resistor. Full sweeps of the resistor have no impact.

I did notice that resistor R8 and R4 are not present and I am not sure if they are required or not. (Picture below)

Thanks,

Steve

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Re: RGB LCD Positive Backlight 16x2

by tritonesub on Mon Mar 18, 2013 10:18 pm

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Re: RGB LCD Positive Backlight 16x2

by adafruit_support_bill on Tue Mar 19, 2013 5:22 am

To simplify, I removed the data pins. I have the backlight powering from the PWM breakout and only the green led grounded. I have the power to 5v and pin 3 is to the resistor. Full sweeps of the resistor have no impact.

That would be the expected behavior. With no data pins connected, there will be nothing to see. Post a clear photo showing your data wiring.
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Re: RGB LCD Positive Backlight 16x2

by tritonesub on Tue Mar 19, 2013 6:10 am

Hi, Sorry about that. I was following the tutorial which said to go back and check the wiring at this point if you couldn't see the top row of boxes when adjusting the pot. Here is a photo of everything wired up and I am running the Adafruit_CharLCD_IPclock_example.py but nothing is visible on the screen regardless of pot position. I have also metered the pot again and it appears to be linear 10k.

Thanks, Steve

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Re: RGB LCD Positive Backlight 16x2

by tritonesub on Tue Mar 19, 2013 6:32 am

Now, while running the Adafruit_CharLCD_IPclock_example.py file sometimes it will show some shapes starting in the middle and then changing before going blank again.

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Re: RGB LCD Positive Backlight 16x2

by adafruit_support_bill on Tue Mar 19, 2013 6:47 am

It appears you have it connected correctly. I would try it without the PWM on the backlight though. These displays are fairly sensitive to noise and you might be picking up some from the long PWM jumpers.
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Re: RGB LCD Positive Backlight 16x2

by tritonesub on Tue Mar 19, 2013 7:51 am

Hi,

I had this breadboarded before and had the same behaviour. I pulled it off to clean things up and to make a clearer picture.
I have followed the instructions in the tutorial and have hooked this up several different ways in an attempt to troubleshoot.

1. I have not powered the back light and still have the same data issues.
2. I have run the back light from each individual pin to ground and powered from +5v and still have the same data issues.
3. I have breadboarded the rgb display as well as jumpering it with the same issues.
4. I have powered the display from the Raspberry Pi's +5V as well as from a separate regulated +5v supply and continue to have the same issues.

All of these attempts have produced the same results that I have documented here.

What is the next step you would like me to take in terms of resolving my support case?

Thanks,

Steve
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Re: RGB LCD Positive Backlight 16x2

by adafruit_support_bill on Tue Mar 19, 2013 8:04 am

Please contact support@adafruit.com with a link to this thread and ask for a replacement display.
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