Ok, so I’m a geek - I’ve always got to have a lot of geek toys around me, and one of the main things is a computer. I’m building the Gemini, as you all know, and with that is an ECU called a MegaSquirt. Most ECU’s have inbuilt datalogging and storage capabilities, or have the ability to send live data to another system (normally a PC). The MegaSquirt is the second style of unit, logging through the serial interface on a PC. This means that I have to have a PC in the car at all times that I want to datalog - which in my case, is as often as possible, to make sure the car is running correctly and so that I can optimise fuel, spark and eventually boost maps.
There’s two ways to have a PC in a car, either have a laptop, or a normal PC in a specialised case. Due to the fact that having a laptop on the seat all the time is annoying - not to mention dangerous, as it’s likely that the laptop is going to spend most of its time flying around the cabin - it’s more practical to have a dedicated PC built into a small enclosure that can be mounted in the car. I’ve had a 7” LCD TV for quite some time - it was supposed to go into the van - but now that the van’s on the back burner, I can use the LCD screen as a display unit for the PC. At this stage, the PC is going to be based upon a MSI MS-6178 motherboard. This is a socket 370 motherboard with onboard video and sound, including TV out. This allows for a single-board solution reducing size and issues with components like video cards shaking loose. It’s also low voltage, low heat and small in size. I won it on eBay for the princely sum of $26.37. I’ve already got a spare celeron 850 which will do the job fine, being fast enough for the intended purpose, and having a low heat output. For the system memory, I’ve got quite a lot of spare SD-RAM, so I’ll try and get 512 megs of PC-133 in there, or at least as much as I can cram into the two RAM slots.
Storage for the PC is yet to be decided. What I’d love to be able to do is run the system entirely off flash media - something like a pair of 1GB CF cards in CF->IDE adaptors on a RAID card. This would mean that the only moving parts in the system are the fans, and the requirements for vibration dampening would be greatly reduced (since HDD’s are rather sensitive to vibration) The main problem is price per gb, but looking on ebay, it’s possible to get a Sandisk 1GB CF card for quite cheap these days.
The operating system to start with would have to be windows, due to the fact that the software for the megasquirt is primarily written in win32. I envision setting up a Linux-based system as an all-in-one solution doing datalogging, media and digital-dash systems for the car sometime in the future. Linux is a lot more flexible with respect to programming and interface, and I know how to tailor the OS for what I require in this system. It’ll allow me to strip the OS back to its bare bones, optimise every part of the system for fast start up and initialisation, then the programming of the interface for what I need to use it easily while still driving the car. I’d love to be able to get it to the point where I can have it boot in around five seconds and use it as the only interface to the car - allowing for a totally digital dash, incorporating all the different gauges needed to drive the car and monitor its health.