Ways to start a Car-PC
Or, how does one minimize the time delay due to computer boot.
Just to simplify the following text, the car-key has four positions:
1, The off position, the key is turned farthest to the left, everything is off, this mode is called OFF.
2: The key is turned one click to the right, in this position the radio is working, I call this position for ON.
3: The key is turned one more click to the right, all systems get power, the warning light are turned on. The key is in this position when the engine is running; I am calling this position for IGNITION.
4: The last are only used to start the engine, it is of no use so I do not give it a name.
Here are some ways I can think of to start the computer:
1: Turning the key to ON start the comp, and turning it to OFF shuts it down (after the specified time delay on the PSU) Takes about 2 Ė 2.5 minutes too boot operating system and start Centrafuse.
2: As 1 above, but OFF hibernates the computer. Takes about 1 minute to start depending on how long time the BIOS takes to boot.
These two are quite safe, you have time to see if the computer shuts down, and to start and shot down is easy, just turn the key. The downside is that you have to wait for the computer to boot.
3: Use the car remote to start the computer when the car is opened, and when the remote close the car the computer also shuts down.
In 3 you donít have to wait for the comp to boot. But in three you do not know if the comp shuts down correctly and if you do not lock the car with the remote the computer will continue to run and you will have to trust the safe guarding on the PSU to not empty the battery.
4: Use the car remote to start the computer when the car is opened, as 3 above, but the computer is turned off when the key is turned to OFF.
5: Start the comp as in three, but, and now it starts to get complicated, use the immobilizer to shut down the computer. If you turn off the car but donít remove the key the immobilizer will not activate, but if you remove the key it will activate in about one minute even if the car is not locked (well I donít know if all cars work this way, but my Saab does).
I think one of 4 or 5, probably 4 would be the best alternative to turn the computer on and off. It starts the computer in ample time so it is up and running when you are about to drive away and it shots down in a safe way.
Well that was a loot of text for something easy made complicated.
Or you could just optimize booting for #1 and #2.
A cold boot should only take 20-30seconds. 45 seconds for a cold boot is the highest I would think for a well setup computer. If you are taking 2 1/2 minutes to boot, you need to optimize big time, and then you wont even need to care about the other ones.
Also there is standby which you forgot.
Consider using a seprate toggle switch completely for on/off but tied into the accessory line on the key as a trigger or whatever you choose . The toggle switch is Much much safer and if you have USB power always on issues this will kill the computer and USB.
For safety this will allow you to kill EVERYTHING in case of emergency while the car is moving in a split second.
Also dont forget to wire your reset to another switch.