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LCD I2C Pi Plate & White on Blue 16x2 LCD
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LCD I2C Pi Plate & White on Blue 16x2 LCD

by sadsaddle on Sat Dec 22, 2012 2:04 pm

I recently purchased PID 181 - Standard blue on white LCD and PID 1107 - I2C Pi Plate.
After assembly and using the python code from github (Adafruit_CharLCDPlate) the five buttons work. Backlight on/off works. But nothing appears in the display
(no cursor, no text). Searching the forums I find this thread and the final post says

http://forums.adafruit.com/viewtopic.php?f=50&t=34609&p=171231&hilit=lcd+raspberry+plate#p171231

please note the deigns is similar but the code we have will NOT work for the i2c backpack , its ONLY for the RGB plate! The code will have to be adapted to support the backpack- no ETA as to when we can get to it.


Should the python code from github (Adafruit_CharLCDPlate) work? If not, what changes would be necessary in the Adafruit_CharLCDPlate python code to make it work?

Thanks
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by tldr on Sat Dec 22, 2012 10:20 pm

have you tried adjusting the contrast?

instructions are at the top of the usage page.
"If I had known it was harmless, I would have killed it myself." - Phillip K. Dick, A Scanner Darkly
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by sadsaddle on Sun Dec 23, 2012 12:30 pm

I should have said in the original post that I have tried adjusting the contrast pot but I never see any characters or cursor.
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by adafruit_support_rick on Sun Dec 23, 2012 2:09 pm

That should work with your Pi. The forum post you referenced is talking about a different device.

Please post detailed photos of both sides of your assembly.

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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by sadsaddle on Sun Dec 23, 2012 10:15 pm

These aren't the greatest photos.
Image
Image
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by sadsaddle on Sun Dec 23, 2012 10:20 pm

I guess I don't understand the Img button.
Maybe you can paste these in a browser.

https://www.dropbox.com/s/ab5knnudl9sskcb/IMG_0430.JPG
https://www.dropbox.com/s/6n7ql0xgqa78oda/IMG_0427.JPG
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by adafruit_support_rick on Mon Dec 24, 2012 10:28 am

I don't see any obvious problems. You probably ought to put the rubber bumper on, though I don't think it's related to your problem.
The 16 solders on the display board are maybe a little blobby?

If the buttons and backlight are working, then it seems like you're not getting power to the display itself. The first three pins in the upper left of the display are GND, power, and contrast, in that order. Touch up those solders and see if it helps any.

If you've got a multimeter, you might check to see what you're getting on those three pins. The voltage on the contrast pin should change when you turn the pot.

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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by adafruit on Mon Dec 24, 2012 1:20 pm

As the original post you quoted states - the code is completely different, it isnt a soldering issue but the chips are different, the pinouts different, etc. No ETA as to when we might get the i2c backpack supported under the pi. right now we only support the LCD Plate
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by adafruit_support_rick on Mon Dec 24, 2012 2:51 pm

@adafruit -

The OP states he is using a PID 1107 LCD pi plate with a standard LCD. I didn't see the 1107 listed, but I assumed it was an earlier, pre-kit PID?

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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by sadsaddle on Mon Dec 24, 2012 9:03 pm

I purchased the product PID 1115 here:

https://www.adafruit.com/products/1115

When it arrived the invoice shows:
Includes:
1 PID 181 Standard LCD + extras
1 PID 1107 I2C controlled 16x2 LCD+Keypad - Raspberry Pi Plate Kit

The PID 1115 was found under Raspberry PI Accessories.

Am I to understand that this does not work with the PI? Where does it say that on the site?

I am a retired firmware developer. How about a schematic or block diagram
to help me make it work myself?
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by sadsaddle on Mon Dec 24, 2012 9:15 pm

Clicking Technical Details for PID 1115 it says:


Dimensions: 2.2" x 3.35"
Comes with a 16x2 Blue & White LCD
Plug and play with any Raspberry Pi
Uses only the I2C (SDA/SCL) pins
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by adafruit_support_rick on Tue Dec 25, 2012 3:44 pm

Sorry for the confusion. PID 1115 is designed for the raspberry pi. You shouldn't have a problem.

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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by sadsaddle on Tue Dec 25, 2012 8:08 pm

First thanks to driverblock for posting on Christmas Day -- really above and beyond.

I checked the voltage on pins 1 & 2 - I get 4.83v with a very cheap mm.

Between 1 and 3 it seems to go through the whole range from 4.8 to 0 depending on the pot position.

Probably ok?
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by adafruit on Tue Dec 25, 2012 9:20 pm

Those are correct voltages!
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Re: LCD I2C Pi Plate & White on Blue 16x2 LCD

by adafruit_support_rick on Wed Dec 26, 2012 11:23 am

The LCD display itself must be defective. Sorry about that. Contact support@adafruit.com for a replacement. Please reference this thread and include your original order number.

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