so what does and what does not work? LCDs are a little “tricky” so it might just take a bit of time to get working but it’s doable
I have recently been playing with a 20x4 LCD since I really need the screen realestate and the Fez 2-line LCD wouldn’t cut it for me. Warning: more advanced electronics than you need to know, but I’ll try to point out what’s relevant to you. Take a look at this link http://bansky.net/blog/2008/10/interfacing-lcd-with-3-wires-from-net-micro-framework/. His diagram is more complex than you need, but is great to help in this case (I think anyway). Just note that the way he’s drawn the connectors on the LCD is out of order - the 15/16 are on the end near 1 so you’re only worried about the PIN NUMBER not it’s relative location.
You really need a resistor, variable resistor (trimpot) is best, to adjust the LCD contrast otherwise you may not see things that you display. This is the “1K” three-pin device shown on the diagram. Get one There are breadboard capable ones - i have one like this http://jaycar.com.au/productView.asp?ID=RT4600&CATID=33&form=CAT&SUBCATID=786
You don’t need the BC548B (yet) or 4094 device. Ignore them for the moment.
(I’ll try to mock this up on a breadboard tonight - 10 + hrs away - and take a photo for you)
You don’t need the wires on pin 15 and 16, they are the backlight, lets just leave them disconnected at the moment.
Often these LCDs need 5v, and wont work with 3v3. We will go thru initially with 3v3 and then if that doesn’t work you may need to go to 5v (and you may need a level translator too, for instance I use an 74LS245 - but lets not get ahead of ourselves too much)
Run a GND wire and a POWER wire from 3v3 from your Mini over to the 2nd breadboard - plug them into different COLUMNS of the grid.
Into the GND column, also plug the wire from LCD1.
Into the PWR column, plug the wire from LCD2.
Plug your trimpot into the breadboard (if you don’t have or don’t get a breadboard one, just solder wires to tags). Run a jumper from the PWR column to one edge of the trimpot, run a jumper from the GND column to the other edge of the trimpot, and then the centre wire runs back to LCD3.
The LCD wires for control (4, 5, 6) and data (11, 12, 13, 14) all go to digital pins - from your pics that is mapped like this:
LCD4 = Di2 (RS)
LCD5 = (not used) (RW)
LCD6 = Di3 (E)
You should consider wiring LCD5 to a pin as well.
Then once you’ve triple checked, turn on your Mini.
Then adjust the trimpot until you can see dark bars on the LCD. If you can’t then you have got something mis-connected or your LCD doesn’t like 3v3. After confirming it’s not a wiring issue, move the PWR link into the Mini’s 5v out pin. Then adjust the trimpot again. Assuming you got it right, you’ll see dark bars - it’s working!
More to come later, get past this point and then we can start thinking about software !