To open source or not to, and if so when??? - Page 1
Forum section: electronics / projects

author: Harvs
author_rank: Super Contributor
timestamp: July 19, 2011, 11:33:31 am
content: So I've got this side project I've been working on for a couple of months that's in essence an automotive monitoring, control, data aquision system built around different boards performing individual functions all linked up by a CAN bus.To date there's been 5 modules that I've been working on, with some more still in the ideas stage:- a low cost display (see attached), actually I only developed this to try out some fab ideas, but it works really nice for the <$15AUD it costs to make. Has touch buttons, ambient light and temp sensor (as seen on the front)- an analog/digital sensor and digital output board (also see attached) that's going to live places like the engine bay, and well, sense and control things. Another <$15 board.- My full display, based on a DOGL 128x64 display and large 32b uC, USB, SDCARD data logging etc. Generally a complex design that's taken most of the time.- A simple GPS to CAN interface, which will sit under a GPS module and allow remote mounting. By putting position/time data onto the bus the datalogging and displays can use the info.- and finally a USB to CAN "programmer" board that allows updating the firmware of any node on the bus via a laptop (without physical access, since some will be burried or potted.)So the first two boards and all their acompanying software is almost finished (it'll be done by the weekend if I don't drink too much beer). And the rest not far off, just really need some cleaning of all the code (which isn't a small task I guess), and finishing the PCB layouts.I did this as a personal project to use in my own, and my mates 4x4's. But I'm wondering if this is something worth bothering to document properly and release as open hardware/software, considering the number of uC projects already out there. Would it simply be a waist of time adding to an already over grown pool of projects on this vast web?And secondly, with a hardware project like this, when should one release? There's identified and documented problems with my initial layouts of both the boards in the photos. There will no doubt be at least one more PCB revision before they go in all my mates 4bys. So considering this will be probably months off because I want to thoroughly test what I've currently got, should I be waiting till everything is perfect before releasing the designs, if at all?

author: ndictu
author_rank: Regular Contributor
timestamp: July 19, 2011, 12:25:14 pm
content: I would say just release whatever you have, even just the design files, firmware etc without any documentation. If there is enough interest people will let you know and then when you know it's worthwhile you can make the documentation and other stuff.Also, in my opinion, it doesn't matter if it's finished or not, you can always just release the new versions as you go.I actually want to make a car monitoring project myself (too much of a noob to do it yet) so I would like to just browse through your design files and learn some things.

author: Harvs
author_rank: Super Contributor
timestamp: July 20, 2011, 07:19:42 am
content: Thanks for the input.In terms of the software, I'd agree. If written using "clean coding" principals then it basically documents itself.However the hardware? I'm not so sure. Releasing the designs without documentation could lead to people taking ideas completely out of context.I'll give an example. The row of TO220 Mosfets long the back of the sensor board are there to drive automotive relays (which can typically take up to around 300mA each). If I released this without documentation, I'm certain someone would look at that and come to the conclusion that they are there for medium/high current drive. After all the cheap mosfets I used are rated to some 60A. However that's not the case at all, this board will depend on having ground at equal potential to the engine block if a number of the passive sensors are to work correctly. To that end, I ruled out having any high current drives on this board due to possible to noise induced in the ground. And therefore, while TO220 mosfets have been used as I picked them up really cheap, the PCB and the gate drive are in no way adequate for more than about 1A per mosfet.While the example I just gave is something I will change on the next PCB revision, it illustrates how undocumented designs could be taken in completely the wrong way, doing more bad than good.