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maplin LED+LCD Displays

Fri Sep 07, 2012 8:26 pm

today i just brought a LED+LCD Display kit from maplin in it contains a assortment of LED/LCD displays im trying to figure out how to connect it to the raspberry pi via GPIO any help would be great

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Re: maplin LED+LCD Displays

Fri Sep 07, 2012 8:35 pm

First thing you'll want to do is pull the manual for these displays and find out what types of interfaces they have. With the pins provided on the Pi you should be able to do 232, SPI, I2C or even CAN (if you write a bit-banging driver which might already exist in the wild). Once you figure out the interface we can probably help a little more.
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Re: maplin LED+LCD Displays

Fri Sep 07, 2012 8:36 pm

okay thanks for the reply

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Re: maplin LED+LCD Displays

Wed Sep 12, 2012 8:52 pm

I got this bag a while ago. As far as I can tell the LCDs are random 'bare glass' ones and aren't really easily usable in any project. It's much better to just buy a HD44780 based display which is fairly easy to interface with, or some SPI based screen that's easily interfaceable like the nokia ones people use with arduinos.

The LED screens are fairly simple. Each segment is just a single led with all their grounds connected to one pin. Just choose a resistor value that makes sure it doesn't pull too much current from the pi and connect the pins to the pi's gpio pins with the ground pin to ground (obviously!).

You can probably test it with two aa or aaa batteries in series and a resistor to find out which pins light which segment.

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Re: maplin LED+LCD Displays

Wed Sep 12, 2012 10:27 pm

The easiest way to interface LCD screens is get a HD44780 type device off ebay. They are really cheap if you order from a Hong Kong seller. I've successfully used 16x2 and 20x4 devices.

http://www.raspberrypi-spy.co.uk/2012/0 ... ht-switch/
http://www.raspberrypi-spy.co.uk/2012/0 ... ng-python/

If your screens are HD44780 compatible then you can use the info and scripts in the above links to interface them to the GPIO header.
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