LCD shield won't work with Leonardo

[cyborg5]

I've got a Adafruit LCD shield with a 16x2 display. The display works just fine with my software. The "hello world" schedule also works properly when the device is connected to an Arduino Uno. However when I unplugged it from the Uno and plug it into my new Arduino Leonardo it does not work. The Leonardo itself does seem to work properly. I was able to successfully upload a mouse control test sketch and it moved my mouse exactly like it should. However for some reason we will not drive the LCD shield. I'm not sure if it's putting any text on the screen but I do know that the backlight will not illuminate so I can't really tell what's going on. Again these exact same sketches on the same shield work perfectly on the Uno. And if there's something wrong with the Leonardo or with my installation is not so wrong that it won't do other things that it is supposed to do.

Any suggestions?

[pburgess]

The Leonardo design has some pin functions moved around, and unfortunately this means that a lot of existing shields won't work with it.

You might be able to run wires from pin 2 to A4 and pin 3 to A5, but I'm not 100% certain that this will make it work.

[cyborg5]

Actually even though I said it's a "shield" I did not constructed as such. I left the pins off and just wired four wires to the ground, +5v, and the two signal wires. The signal wires running to A4 and A5 exactly as they do on the Uno.

I'm not sure I understand what you mean about the pinouts being different between the Leonardo and the Uno. They are labeled exactly the same.

Any other suggestions?

[adafruit_support_bill]

I2C (aka TWI) is on pins 2 & 3 of the Leo, instead of pin A4 & A5 of the UNO.
http://arduino.cc/en/Main/ArduinoBoardLeonardo

[cyborg5]

Many thanks. I just managed to figure that one out after some research on my own. Was just about to post a message here.

Unfortunately that's going to cause me a whole other bit of conflicts because I was already using pin 3 for some other uses. Which included the use of Timer2. Now I've got to go recode everything to use Timer1.

Of course that's assuming I know how to do that

I'll figure it out eventually.

Thanks for leading me in the right direction.

[Ziauddin Ansari]

Since you have made the shield yourself, all you have to do is to connect the wires to 2 and 3 of Leonardo instead 0f A4 and A5