Saturday, December 14, 2013

LCDuino and shields

It occurred to me that, while I think that the Arduino Uno architecture makes breadboarding more difficult, there's clearly quite a bit of value in existing shields.

To that end, I've designed an LCDuino shield adapter. It's the footprint of an Arduino Uno (thanks to the AdaFruit Uno library), but with the pins (except for the irrelevant ones) all connected up to an LCDuino header.

There is also a 2.1mm barrel connector for power, which is connected also to the VIN pin of the shield.

There are some differences to be aware of between a real Uno and the LCDuino + shield adapter:

  1. There is no provision at all for 3.3 volt power. The 3V pin is not connected.
  2. A4 and A5 are actually connected to A6 and A7. A4 and A5 are used for the i2c bus, which is exposed on the i2c pins which were an extension of the original shield specification. Shields that expect i2c to work on A4 and A5 won't.
  3. There is no provision for selecting either 5 volts from USB or from the barrel connector. You should not connect both at the same time.
  4. There are no LEDs for RX, TX, D13 or power, and there is no reset button. Those are already present on LCDuino.
  5. The ISP connector is in a different location. Its orientation, however, is the same.

The board is on my OSHPark profile if anyone is interested.

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