Open Bicycle Computer

In the old hacker fashion I decided to repair the wheel and the treadle myself. A whole new world with a whole new lingo opened up to me today, thanks to youtube. So far I've only managed to rip off the thread of the back-wheel rod, everything else looks still intact. I'm a bit late for this years cycling season, but it's immanent for my health and well being, that this thing rolls again. Tomorrow I'll try to recut the thread on the rod and the day after I'll receive some special tools for repairing bikes. The cost was about half of a home improvement store bike, but I want to learn this stuff and see if I can fix it by myself.

You probably know how it is with projects - you're motivated at some point and then again totally lost focus and interest. And necessity is the mother of invention. This is not an excuse log. I'll always take a look at my projects and think about everyone for a minute.

There is a professional way to make this project and a diy/hackish-way to do it. This should probably be made with BTLE and be connected to your phone, but this would compromise my initial - off the phone - concept. I still have a BTLE dev kit - the wunderbar - with 6 sensor boards and one "mother"board somewhere and I feel like I owe them a project since I've won this and it's probably what they expected when they handed them out (because reasons). It's not that easy to hack, I guess. I'd have to work with the onboard BTLE chip and there are more people that are used to "work" with arduino.

I need a quick hacked together prototype to start writing some more code though. It should be something anyone can build with a few parts - basically a LiPo cell, a 5V boost converter and an arduino connected to a 1602 LCD character display with a hall effect sensor connected. I'm not happy with 5Vs though. the battery power should be measured with the arduino, too. This is a total waste of money in comparison to a 5 dollar computer and basically what I've achieved already. Next step would has to be logging. That's the killer-app / the pitch. Am I going in the right direction?

This feels like two projects! Damn! One is easy to hack together but not efficient, one is efficient but not easy to hack.

What should be the key point here?

I placed the breadboard upside down by accident. Here is a shaky video of the prototype.

Since mr.jb.swes project Multicharger is all over my feed, hackaday.com (congrats!) and this page too, I'm thinking far ahead of my timeline. To keep it simple I want a single cell setup, boosting the voltage up to 5V. The hall effect sensors are only working with 5V so I started my first compromise, which turned out to be good, because this way I can monitor the power from the cell with an analog in pin of the arduino and everything gets more tinkerer-friendly. Now I need a way to get the dynamo voltages down to 3.5V to charge the LiFePo accordingly. Sounds overly complicated to convert from 6V to 3.5V to 5V but a battery comes in handy when you are standing because of a traffic light in the nights and you don't want your lights (or computer) to go off.

it's not much right now, but here is my sketch repo 

https://github.com/davedarko/OpenBikeComputer

I will add this in the links, too.

The software so far can be seen in this video log I made. I kind of have this annoying bored-sounding, really slow voice on videos, sorry for that :D I'm really thinking while talking since I'm not a native speaker.

Today I received the I2C OLED display and the first thing I wanted to do was creating an I2C/IIC display header for it. Going through many tutorials I started my own library today with my first entry; the IIC display thin.