wiki:Prototype/One
Last modified 7 years ago

First Prototype

Ok, it is winter time and it is cold outside, and I started to build the first prototype. The problem is, that I am working only in my free time, so I have not much time to spend on this project. Therefor it just continues slowly. Ok, nevermind, let's rock. First of all, take care of the size for the self-made PCBs where I will put my prototype on:

http://www.tevs.eu/media/images/projects/openbm/DSCI2740.JPG.small.jpg

Next thought was, how to connect that board. I decided to do it cable, by cable, in this way:

http://www.tevs.eu/media/images/projects/openbm/DSCI2742.JPG.small.jpg

Which ended up in a disaster of cables. The connections were unstable and everytime I moved the small PCBs the connection even breaked down. So, don't even try this. I had to make this experience, to make it next time better:

http://www.tevs.eu/media/images/projects/openbm/DSCI2805.JPG.small.jpg http://www.tevs.eu/media/images/projects/openbm/DSCI2948.JPG.small.jpg

The board is driven by an  ATmega32 uC with 32K flash memory running at 4.4MHz. As connection to BMW's bus-system (i.e. I-Bus) I am using  TH3122 chip from Melexis.

After trying several things, I just didn't came up to a good result, because this amount of cables was just unhandable. The comparison of the PDIP and TQFP package of the same uC shows the differences, so I had to get everything smaller, otherwise the project will not survive. In the right part of the image, you can see the differences in sizes between TQFP and PDIP package of the ATmega32 microcontroller:

http://www.tevs.eu/media/images/projects/openbm/DSCI2949.JPG.small.jpg

So the next step would be to make everything smaller and handy. Hence, I started a development of SMD based board which would replace this messy wirings. See, next chapter.


Pay methods