LCD display not working, black

[robertko]

Hi,
I just constructed this LCD display with shield: https://learn.adafruit.com/adafruit-16x ... i/assembly.

But when I run my code, the display is dark, and is always dark.
My code runs fine on the Raspberry.
I know this is a very long shot, but maby anyone know why the display just stays dark and nothing shows? I noticed that the holes for the shield was 2 more then for the LCD display, maby it mattered at which end i put the 16 pins? at the right side or the left?

I have double checked the smoldings, and tried alot of ways to compile/run the code for the LCD.

Thx

[texy]

Hi and welcome to the forum.
Have you tried adjusting the pot ?
Even if there is another problem, you shuld at least see a row of solid blocks on the display, but if the contrast is not set, you may
see just black, ie nothing, as you are seeing.
Have you checked the voltages on pins 2 and 3 compared to GND?

Texy

[robertko]

Thanks for your reply!

Sorry, the pot is the contrast adjuster? The constrast is adjustable, so if I turn it all the way the display goes blank. I take that as the display is recieving Power.
How do I check if the voltages on the two pins? Do I need some kind of tool?

Thanks

[BMS Doug]

I noticed that the holes for the shield was 2 more then for the LCD display, maby it mattered at which end i put the 16 pins? at the right side or the left?

Finally, we place the LCD.
Break off a piece of 18 or 16 pin header from the stick in the kit.

If you have an RGB display, you'll need 18, for a blue&white you'll need 16

Place the header into the remaining slot with the long ends of the pins sticking UP. If you have only 16 pins, leave the two rightmost pads empty

WARNING: If you're using the new Raspberry Pi model B+ with 4 USB ports you will need to take some extra steps to ensure the backlight resistor leads do not touch the USB ports and short out. See the steps below for more details.

There is current limiting in the resistor circuit so it shouldn't damage the Pi if there is a short, but to be sure it is advised to cover the USB port and resistor leads in a few layers of electrical tape. Be sure to cut the resistor leads as short as possible with flush cutters and try to ensure there are no sharp edges from the cut leads or solder. See the photo with arrows pointing to the two locations you should place electrical tape.

[robertko]

Thank you but I have made sure that there is no Contact between them two.
And the two pins on the outer right are empty.

[robertko]

I have ran a check featured here: https://learn.adafruit.com/adafruit-16x ... y-pi/usage
Which as far as I understand checks the pinouts. And my clearly doesn't look right.. What have gone wrong? Did I damage the chip why my solding?

0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- UU -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

What is the 10xb? Do I need to blacklist it? What driver is it?
Thanks

[DougieLawson]

Don't worry about 0x1B that address is reserved by the linux kernel for I2S sound devices.

[robertko]

Ok I see,
according to https://learn.adafruit.com/adafruits-ra ... guring-i2c I should have a different i2cdetect printout. Is this because I have poorly solded or is this printout just relative to each OS?