October 2, 2013 /
With the advances of shrinking technology it’s becoming more and more easier to roll your own every day items. Ever thought of making your own watch ? Sure you have, it was probably going to turn out larger than you anticipated too huh? How’s 1.5mm thick sound ? Sounds pretty good to me too. Zak has a really awesome writeup of him rolling his own watch.
The display is a 0.96″ OLED display (128×64 pixels), it uses a DS3231M RTC, 2 LEDs, a buzzer, a 3 way switch and runs off of a 150mah LiPo battery. Impressive! Features of the software include, window animations, up to 10 alarms, games, stopwatch, and flashlight mode.
Power consumption numbers are decent too. 6ua in sleep mode, and 10ma with normal on. That means depending on how much time you spend with the screen on will dictate how long your charge will last. This puts you anywhere between 15 hours and 3 years. With those sort of numbers and a modest use of your watch you should be able to get 15-30 days out of a single charge.
The Schematic and source code are available on Zak’s web site, a long with more photos of the build. Enjoy a video and a few more pics after the break.
September 26, 2013 /
Believe it or not, it’s actually quite difficult to generate random numbers on computers and microcontrollers. I’m talking about true random. A lot of the randomness computers use isn’t random at all, it’s predictive (or pseudo random). Difficult, but still predictive. It’s important when doing cryptographic functions to use a good random source.
So f4grx decided to build a random circuit and do some analysis on it. The circuit design is built around the idea of using an open collector on a transistor. What’s essentially going to happen is tiny electrical noise in the air is going to cause the circuit to produce 1′s and 0′s which then can be used to plot random.
Interesting read. Check out f4grx’s experience.
September 22, 2013 /
I know this awesome project is a few weeks old but I’m going to use the fact that Rupert recently posted an update as my excuse to share it on hackalizer. As the title implies the V-USB Media Volume Control project is using V-USB. V-USB is software which makes it possible to add low-speed USB to almost any AVR microcontroller without any additional hardware.
From selecting the perfect rotary encoder to designing and etching his own PCB and eventually making a custom enclosure, this project shows is all. Rupert explains some of the minor but important differences of the rotary encoder such as the number of detents and amount of force required to turn the knob and press the button. He also shares an important lesson on load capacitance with regards to the crystal on his home-brew board. Check out the build video after the break.
September 18, 2013 /
Admit it, you still love LED throwies, everyone does! So does David. After viewing an article on very low power LED fireflies by Karl Lunt, David decided to build the project (and does a good job of documenting the process to reproduce it). The LED fireflies use the LED as a photosensor to detect when there is light so it knows when to go to sleep, thus by saving power by not doing anything with the lights on.
The build works off of a CR2032 coin cell battery, and everything is dead-bug soldered together. The microcontroller is an ATTiny13a which is already a low power microcontroller, but by using the LED as a light sensor periodically, the microcontroller knows when to sleep and doesn’t wake up until the light level changes below a threshold. This allows the firefly to last a really long time on that single coin cell.
David added a little spin on the original by wrapping it in a waterproof enclosure (à la sauce container) and a magnet (so it can be a throwie). This looks like a fun build.
Source code can be found on Karl’s site. David’s writeup can be found here. Video after the break.