code, circuits, & construction

Sometimes you need to manage multiple events with a microcontroller that all require different timing.  For example, you might want to control a servomotor (which requires a 20 millisecond delay), blink an LED once a second, and read some sensors (which should be read as frequently as possible.  One way to handle this is to keep track of a time stamp for each event.  You constantly read the millis() and if enough time has elapsed since the last time a particular event occured, you do it again.

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This example uses a digital input to control a fading LED. The LED turns on when the switch goes from off to on, then fades slowly to black.  It illustrates two principles:  the idea of edge detection or state change detection, and the idea of time delay without using delay().

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ITP just got some nifty flat panel mounts that can rotate 360 degrees. They’re very easy to move, it takes only one hand. When I saw them, I thought, “what good is a rotating mount if the content on the screen can’t rotate too?” So I came up with a little system to sense the screen’s rotation. Here’s how to turn those screens into a very big iPhone. Thanks to Michael Dory for his help in coding this and Dan O’Sullivan for the final clue.

The screens have a mac mini mounted on the back to display digital content. I added an Arduino with an accelerometer mounted on it to sense the angle of the screen’s rotation, then sent that data into Processing.  This example doesn’t do much, but the code can be re-used for any Processing application that needs to know the screen’s rotation.

Rory Nugent modified my existing code and made it much better.  I’ve incorporated his changes here, thanks Rory.

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Here’s a short Wiring/Arduino program that waits for a connection to the microcontroller via a Lantronix device, and sends out an analog reading when it’s got a connection.

The Lantronix device is in connectMode D4, and the TX is connected to the Arduino’s RX and vice versa.

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