16x2 LCD + Raspberry Pi - I'm stuck

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voorTech
 
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16x2 LCD + Raspberry Pi - I'm stuck

Post by voorTech »

I followed the tutorial on how to hook up the 16x2 LCD to the Pi using the PiCobbler. I had it all set up and working using a breadbard.
I decided to transfer it to a prototype board for a more permanent setup. But I can't get it to work.
THe LCD turns on, the potentiometer works in adjusting the brightness, but nothing appears on the LCD when I run the python test script, or
my own script.
I must have checked the wiring 10 times, but no luck. I have a feeling that I'm missing someting very basic, but I don't know how
to trouble shoot it.
Any ideas or pointers will be much appreciated!

Rob.

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adafruit_support_bill
 
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Re: 16x2 LCD + Raspberry Pi - I'm stuck

Post by adafruit_support_bill »

If you post some photos showing all of your soldering and connections, we'll take a look.

voorTech
 
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Re: 16x2 LCD + Raspberry Pi - I'm stuck

Post by voorTech »

I was worried you'd ask that :)
It's my first project, and I probably broke every soldering rule (like using same color wiring), but here are a couple pics:

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adafruit_support_mike
 
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Re: 16x2 LCD + Raspberry Pi - I'm stuck

Post by adafruit_support_mike »

Some of the connections to the LCD board look like they don't have any solder.

Take a look at our tutorial on soldering: https://learn.adafruit.com/adafruit-gui ... soldering/ then give all the joints another go.

The nice thing about soldering is that with enough flux and a bit of solder-wick to clean up the messes, you can take almost as many tries as you want.

voorTech
 
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Joined: Wed Nov 07, 2012 6:14 pm

Re: 16x2 LCD + Raspberry Pi - I'm stuck

Post by voorTech »

Thanks for the tip, I went over the connections again and fixed up the ones on the LCD board... no luck though.... :(

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adafruit_support_mike
 
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Re: 16x2 LCD + Raspberry Pi - I'm stuck

Post by adafruit_support_mike »

This is the point where I haul out the colored pens.

Problems like this tend to involve one or more detail that's been overlooked, and the only way to really nail those is to be methodical and thorough.

Start by drawing a circuit diagram, then use colors to mark all the 'nodes'.. places that should all be essentially the same wire:
erdi-current-source.jpg
erdi-current-source.jpg (28.64 KiB) Viewed 299 times
then I number the nodes, haul out the multimeter, set it for continuity, and start checking connections between the component leads and the nodes. It's tedious (the diagram above has something like 70 connections), but sometimes it has to be done. All the connections have to work for the circuit to operate, and the laws of physics will spot the bad joint whether I do or not.

If all the connections are good, I go back and start testing for exclusion between nodes that are physically close together but should be electrically isolated from each other.

Any non-trivial circuit has more connections and exclusions than you can keep in your head. Make a map, then mark the bejeebers out of it so you know where you've been and where you still need to go.

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