BattleaxeAU

Your garden-variety (7805) 5V linear regulator will work with inputs up to 20V. It won't burn up with just a few LEDs running off it. Don't forget to put it on the right side of the dev board's regulator (and don't stuff up the polarity like I did the last time I soldered one :problem:).

I'd second cbe in suggesting that once the car is started, it should never be shut off mid-drive. The system only needs to stuff up once to cause a crash, and my experience of RFID is that it often takes a couple of goes to work. I wonder if you could simulate a flat battery, instead of cutting power to the starter motor completely? Just wondering, don't actually have experience with automotive electronics.

Thanks for the discussion everyone. I'll give a magnetic switch a shot once I've got the basic monitor up and running. I also thought I might try copper tape on the door's seal to make a rudimentary switch. That would actually solve the problem. But I guess I have ulterior motives

Excellent suggestions. I've got a few DS18B20s so I'll use one in my build, but using the internal sensor would bring the cost down. What do you think is the best way to make a door switch? I'm thinking some thin copper tape on both sides of the seal would be nice. People have used magnets or even reflectivity sensors.

We have an old freezer in the sharehouse where I live, and a few times its door has come ajar because the door seal isn't great. After the door discovered is discovered ajar the difficult question is whether to throw out the frozen food or not. Clearly this is a problem for electronics. The hardware is an MSP430G2???, a DS18B20 temperature sensor inside the freezer and a 4x7 segment display. Also a shift register to save on MCU pins. The data I'm interested in tracking are: [*:1e7tngdp]Current temperature[*:1e7tngdp]Max temperature[*:1e7tngdp]Time above -15 degrees calcius (5 Fa

Hi, I'm an amateur, I've only been mucking around with micro-controllers for a couple of years. Mostly arduino and discrete Atmel chips that can be programmed by arduino. I'm using my Launchpad as an opportunity to switch to proper MCU coding in C (yes, I do know about energia, but I want to learn this stuff). I'm also happy to have some MCUs which will run off batteries for longer than the Atmels. I just coded my "hello world", which controls a 7segment display using a shift register. 43oh site has been extremely helpful so far. Thanks!