Countdown to EV3 - The Mindstorms Alarm Clock Sensor

Discussion specific to projects ideas and support.

Countdown to EV3 - The Mindstorms Alarm Clock Sensor

Postby dlech27 » 20 Aug 2013, 03:12

Hello robot-heads,

My NXT has been gathering dust for the last year, but news of the EV3 has got me really excited about it again. In anticipation, I have turned a LEGO Star Wars alarm clock into a Mindstorms sensor to countdown the days until the EV3 is officially released on the first of September.

If anyone is interested in all of the technical details, I might write up a step-by-step how-to someday, but for now, here is the short version...

I have a LEGO Star Wars alarm clock that was just laying around doing nothing.

I thought, "Wouldn't it be nifty if this could be hooked up to my NXT". So, I got a sensor kit from mindsensors and made it happen. It basically involved cutting some traces on the PCB in the clock and adding header pins to it and also creating a circuit to drive the piezo buzzer.

So far, the alarm "hand" of the clock and the snooze button are inputs and the alarm buzzer is an output. Here is a little video if it in action. It finds the alarm hand, then completes one complete rotation of the hour hand and counts the degrees traveled by the motor to calibrate it. Once calibrated, it moves to a position that indicates how long until the EV3 release. The hour hand is now a day hand (one full rotation = 12 days) and the minute hand is a 24-hour hand (one full rotation = 24 hours). The video shows that it is 12 days and about 8 hours (US CDT).

I have a couple more ideas for this. The alarm clock also came with a light bulb (the kind with a filament, not a LED) that lights up when you press the snooze button, but it pulls a bit too much current (80mA) for the PCF8574 (max 25mA). I would like to find a LED to replace it (the ones I have are too big). Also, the red button on top is a push-on, push-off switch that mechanically engages or disengages the alarm mechanism. I would like to break the mechanical linkage and turn it into an input as well.

This leaves 3 ports left on the PCF8574 chip. What else should I make this thing do?
Posts: 9
Joined: 19 Aug 2013, 23:08

Return to Mindstorms Projects

Who is online

Users browsing this forum: No registered users and 11 guests