LCD-based QR clock

February 28, 2013 By 11 Comments

new-take-on-qr-clock

Here’s a new take on the QR clock concept that uses an LCD display. The concept comes from the work [ch00f] put into his two versions of a QR clock (both of which used LED arrays). The time of day is encoded using the Quick Response Code standard. This version generates a new code each second which encapsulates date, hour, minute, and second information. If you look at the image on the left you’ll notice the code is not centered. Take a look at the video after the break and you’ll see that’s because it’s bouncing around the LCD like a screensaver. Watch a little longer and you’ll see the psychedelic effects shown in the image on the right.

A PIC32 is driving the display. It’s connected to a DCF77 radio module which feeds the system atomic clock data. The color plasma effects are used to show when the device has locked onto the radio signal.

[Read more...]

Filed Under: clock hacks Tagged With: , , , , ,

Sunrise alarm clock uses DCF77 for perfect time

December 6, 2012 By 10 Comments

sunrise-alarm-clock-dcf77

Here’s a sunrise alarm clock that keeps perfect time. It was designed and built by [Renaud Schleck] who also published a post detailing the process.

As you can see, a series of white LEDs inside of the transparent case which provide the simulated sunrise. As the days get short and the nights longer we do see the benefit of having your clock brighten the room before it jolts you out of your slumber. Speaking of, that alarm sound seems to be the weak link in his design. He’s using a square wave smoothed with capacitors to drive a speaker at either end of the case. We didn’t hear an example but we imagine this not the most gentle of sounds.

The rest of the design is quite well done. He’s using a 4×20 Character LCD display and adjusts the backlight using PWM. A DCF77 radio feeds data from an atomic clock signal to the MSP430 chip which runs the clock. There’s even a battery backup in case the power goes out.

We just saw a project yesterday that aims to improve signal quality with a DCF77 radio.

[via Reddit]

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DCF77 signal filtering and decoding

December 4, 2012 By 21 Comments

dcf77-filtering-and-decoding

[Udo] decided to build a clock using the DCF77 radio module seen above. This of course has been done before: the hardware draws a clock signal from the atomic clock in Braunschweig, Germany. So he grabbed a library for Arduino and got to work. But he was getting rather poor results and upon further investigation realized that the library had been written for 20 Hz modules and his operates at 300 Hz. This means better accuracy but the drawback is that the hardware is more susceptible to noise.

So began his journey to filter, process, and decode the DCF77 protocol. That link goes to the project overview. It will be in several parts all of which will be linked on that page. So far he has applied a low-pass filter and coded some exponential smoothing. He has yet to write the other four parts, but does mention that early testing shows that this technique will make the reception better than what is achieved with commercially available clocks. He was able to lock onto a signal that had more than 80% noise ratio. That’s impressive!

Just want to see a clock that uses a DCF77 module? Check out this PIC-based atomic clock.

Filed Under: radio hacks Tagged With: , , , ,