MitxPC M3-ATX - Manual (Page 3)

P1: Sends ON pulse to motherboard when ignition is ON for more than 2 seconds,sends
OFF pulse to motherboard 5 seconds after ignition is turned off. Waits another 1
minute and then shuts down 5VSB to conserve battery. In this mode, the M3-ATX
consumes less than 0.5mA. This is our recommended setting.
P2: Sends ON pulse to motherboard when ignition is ON for more than 2 seconds,
sends OFF pulse to motherboard 60 seconds after ignition is turned off. Waits another 5
minutes and then shuts down 5VSB to conserve battery.
P3: Sends ON pulse to motherboard when ignition is ON for more than 2 seconds,
sends OFF pulse to motherboard 30 minutes after ignition is turned off. Waits another 2
hours and then shuts down 5VSB to conserve battery.
P4: Can be set to any value. Setting can be done via an optional serial cable.
(Default values for P4 are Off-delay=30sec, Hard-off=30sec)
NOTE: To reset to the M3-ATX settings to the factory defaults (in case changes were
made via the serial uplink), simply power off the unit, connect a jumper as shown and
then power back up. The LED light will start to flash rapidly indicating that the factory
defaults were loaded. Don’t forget to Remove jumper when done!.
Power challenges in a Vehicle PC: One of most difficult tasks of operating a PC in a
vehicle is power consumption while the computer is OFF. Even when your computer is
OFF, it will still consume about 100mA on the 5V rail. When the computer is in the
suspend mode, it will consume even more power, because the RAM needs to be
powered at all times.
No matter how big your battery is, you will eventually drain it if proper actions are not
taken.
The M3-ATX is addressing these issues by cutting off the 5VSB rail after a pre-defined
amount of time (see jumper chart, HARDOFF). During the HARDOFF if the battery level
drops below 11.2V for more than one minute, M3-ATX will shut down and re-activate only
when the input voltage is > 12V.
Engine Cranks, under-voltage and over-voltage situations. Another difficult task is
maintaining stable power to your PC. While car batteries are rated at 12V, they actually
provide voltages in between 7-11V (engine cranks) or as high as 80 volts (load dump).
Most of the times, your battery will stay at 13.5V (while car is running) but extra
precautions need to take place in order to prevent such situations. M3-ATX can operate
as low as 6V and as high as 24V while providing strict regulation on all rails along with
input voltage clamping and reverse protection.
Loud amplifier pops when PC starts. If your PC is connected to your car amplifier, you
will hear a loud pop when the computer is first started. The M3-ATX has an ‘anti-thump’
control that will keep your amp OFF while the PC starts. Simply connect the white wire
from your M3-ATX cable harness to your amplifier remote control pin.
Mode of operation
1)
Ignition=OFF. Nothing happens. M3-ATX is waiting for ignition signals.
2)
Ignition=ON. M3-ATX waits for 2-3 seconds then turns on the 5Vsb rail. After another second M3-ATX
sends an“ON” signal to the motherboard via the 2 wires connected to the motherboard’s ON/OFF pins.
The motherboardwill turn ON and your system should start booting.
M3-ATX User Guide Page 3