Thursday Nov 08, 2012

RPi and Java Embedded GPIO: Hooking Up Your Wires for Java

So, you bought your blue jumper wires, your LEDs, your resistors, your breadboard, and your fill of Fry's for the day. How do you hook this cool stuff up to write Java code to blink them LEDs?

I'll step you through it. First look at that pinout diagram of the GPIO header that's on your RPi. Find the pins in the corner of your RPi board and make sure to orient it the right way. The upper left corner pin should have the characters "P1" next to it on the board. That pin next to "P1" is your Pin #1 (in the diagram).

Then, you can start counting left, right, next row, left, right, next row, left, right, and so on: Pins # 1, 2, next row, 3, 4, next row, 5, 6, and so on.

Take one blue jumper wire and connect to Pin # 3 (GPIO0). Connect the other end to a resistor and then the other end of the resistor into the breadboard. Each row of grouped-together holes on a breadboard are connected, so plug in the short-end of a common cathode LED (long-end of a common anode LED) into a hole that is in the same grouping as where the resistor is plugged in. Then, connect the other end of the LED back to Pin # 6 (GND) on the RPi GPIO header.

Now you have your first LED connected ready for you to write some Java code to turn it on and off. (As, extra credit you can connect 7 other LEDs the same way to with one lead to Pins # 5, 7, 11, 13, 15, 19 & 21). Whew! That wasn't so bad, was it? Next blog post on this thread will have some Java source code for you to try...

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Hinkmond Wong's blog on making Machine to Machine (M2M) and the Incredible Internet of Things (IoT) smarter with Java Embedded Technologies

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