VERACRUZ(EN) >2010 > G 3.8 DOHC > Body Electrical System > Electro chromic Inside Rear View Mirror > Compass Mirror>Description and Operation  
Description
The compass feature is designed to be integrated into an electro chromic interior rearview mirror.
The mirror assembly shall display a compass heading.
The compass mirror then take the sensor information to determine static field strengths and rotating field information to determine an accurate compass heading.
Specification
Item
 Standard value
Rate voltage
 DC 12V
Operating voltage range
 DC9 ~ 16V
Operating temperature range
 -30 ~ +65°C
Direction display
 8
Renewal time
 2 sec.

Switch Point Accuracy
The compass module shall, while compensating for the vehicle magnetic fields, until the Earth's varying magnetic fields to determine direction.
[Switch points]
Switch point
 Heading ± 10°
N - NE
 22.5
NE - E
 67.5
E - SE
 112.5
SE - S
 157.5
S - SW
 202.5
SW - W
 247.5
W - NW
 292.5
NW - N
 337.5

There should be hysteresis at each switch point.
Switch points between the 8 cardinal directions, these switch points are ± 10°

Compass display interval
Compass display should be updated at every two seconds.
Function
The compass can be turned ON and OFF and will remember the last state when the ignition is cycled. To turn the display feature ON/OFF :
1.
Press and release the feature control button (A) to turn the display feature OFF.
2.
Press and release the feature control button (A) again to turn the display back ON.
Additional options can be set with press and hold sequences of the feature control button (A) and are detailed below.

There is a difference between magnetic north and true north. The compass in the mirror can compensate for this difference when it knows the magnetic zone in which it is operating. This is set either by the dealer or by the user.