The DSSC v0.9 - Startup / Shutdown Controller

Features:
  • Master shutdown circuit for preventing a dead car battery
  • Multiple user defined start relays
  • Serial port shutdown signal
  • ACPI motherboard header trigger/toggle
  • Multiple user adjustable delays for LCD, Amplifier, or doorlock/window controller.
  • LEDs for adjusting the delays, and LED headers for remote led location
  • User adjustable delayed shutdown (and PC/microprocessor adjustable serial port delay for Valet/Fuelup/etc)
  • Valet bypass switch
Some of the points of this circuit that have been requested have already been incorporated into the design. I'd like to clarify how they're [designed] to be used. You may find other ways of using these features to better suit your specific application.

For example, I'm using the circuit in the following manner:
  • I have a 4 second delay configured for the MASTER POWER RELAY. This is to prevent any issues with cold-cranking of the car. Cold cranking is starting the vehicle from the engine-off state to the engine-running state. 4 seconds is probably too much, but it's what I'm using at the present time. A saavy user can probably set this delay to 0 and use an inline capacitor to keep the voltage stable. This has been included for flexibility.
  • The second "trimmer pot" adjustable delay - is used for the ACPI "pulse". This pulse is just a 1 second closure of 2 pins - the ACPI pins. A relay momentarily closes for a second which simulates pressing the power button on your motherboard. This is used to turn the actual computer on and off.
  • The third adjustable delay - is used for my Amplifier turn on _and_ my parallel port relay board. The delayed Amplifier turn on, aleviates the POP! that goes with turning on an amplifier simultaneously with other devices. The reason for the parallel relay board delay is because the motherboard will typically "toggle" the Parallel port pins sporiadically (varies greatly by motherboard manufacturer). The result of this (with the relay board connected to doorlocks, windows, sunroof, trunk, etc.) would be a car that acted like the out-of-control BMW iDrive vehicles. The ones that randomly do strange things because of the secondary computer freaking out. This use isn't required, however, it's provided for convenience.
  • The fourth adjustable delay - is used to turn on the LCD display after the system has either a) booted, or b) booted to a nice boot/status screen. This is purely an aestheic effect. It will allow you to bypass the BIOS boot screens and present your custom screen, or just turn on when the system is fully booted and ready to run.
  • The fifth adjustable delay - is used to specify the amount of time that passes from the time the ACC line turns "off" (key removed) until the time when the power is COMPLETELY TURNED OFF to all devices that are connected to the circuit. This delay is adjustable up to 20 minutes. This is used as a safety feature and to help prevent a dead car battery. After your engine has been turned off for at most 20 minutes, the computer, amps, add-on boards, LCDs etc, will be forced off by having their power pulled out from under them.
  • The serial port and header - can be used as an alternative to using ACPI to power down a DashPC (secondary car computer). The header is simply 10 pins (similar to jumpers on a motherboard) that are arranged such that you can use an external serial port connector if you'd prefer.
  • LEDs and LED headers - The LEDs are used to display POWER ON status, and DELAY sequences. When a DELAY is happening, the LED is lit. When the RELAY has switched, the LED goes off. This is by design to help in making delay adjustments. The LED headers are used for the people that want to remote mount the LEDs (perhaps in the dashboard or the motherboard case).
  • The VALET switch - is used to keep the PC on while you pump your gas, or get groceries or whatever. It's adjustable up to 20 minutes. If you put a switch here, it will emulate the ACC line (key in the ignition) and can be kept on indefinately. In this state, the MASTER power control may not prevent a dead car battery. The next revision may include a low battery indicator to FORCE a SHUTDOWN of all connected devices.
  • The circuit requires a minimum of 3 connections: ACC, GND, +12V. However, it won't do much but blink lights. A reasonable configuration will need 5 (2 for ACPI+3 named above). A more thorough use can use up to 14 or more connections! This configuration would use the remote LED headers, the serial port (or ACPI), the AMP delay, the LCD delay, and the standard power connectors. It's a very flexible circuit.