Well, I had a little "extra" room on another circuit board I designed, so I used the "wasted" space for part 1 of my engine controller.
This is the first board. It contains the "brains" of the operation.. A PIC, a voltage regulator, a real time clock and crystal, some EEPROM, and a little extra hardware to drive an LCD display. This is kind of a general purpose controller board I can use for other projects besides the "roid controller. Here's the board and parts for the controller all lined up and ready to load...
http://sweetwatergems.weirdstuffwemake.com/geek/images/controller%20board_597.jpgBoard #2 will be the "muscle board", with MOSFET output drivers to control solenoids, relays, or valves to turn stuff on and off, and input buffering hardware for the assortment of inputs form the Listeroid and it's surroundings. It's still to be designed.
I've also got a couple of temperature sensor boards set up. The "low temp" boards (up to 125C / 257F) use a MCP9800 temp sensor. That should be good for measuring coolant temp and engine shed temp. The "high temp" board uses a MAX6675 sensor with a type K probe. That one can read up to 1024C/1875F for exhaust gas temperature. Both temperature boards output serial temperature data and interface easily with the controller board.
Still working out the sensors for fuel level and crankcase oil level, but I like BruceM's "floating magnet in a tube" idea and may play along those lines to start with.
Here's a low temp sensor board already loaded. I've built and used several of these already and they're great. The pads on the right are for +5v, ground, a serial data line, a clock line and an "alarm" output. I don't generally use the alarm out so it takes 4 wires to connect it to a controller.
http://sweetwatergems.weirdstuffwemake.com/geek/images/mcp9800_625.jpgNo photo of the high temp sensor board but it looks much like the low temp board with a type K probe dangling off one end.
Will post more as I get it built...
