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Figure 10 Digital key “I-Button” DS1990A connection scheme
Fuel tank sensors
A fuel tank level sensor exists in most of the cars, which
shows the approximate fuel level in the driver’s indicator panel.
It is possible to connect FM5500 Analog input (if sensor returns
analogue signal proportional to fuel level). Figure describes the
connection scheme to the FM5500 and fuel tank sensor. After
the connection to the tank fuel level sensor, calibration is
needed. Calibrations needed due of the fact that most fuel tank
sensors are not linear. Calibration is being performing by
measuring voltage dependence on volume of fuel in tank.
Figure 11 Fuel sensor scheme
Alarm buttons, door sensors, etc
Alarm buttons, door sensors, ignition, etc return two states: high or low voltage. Digital
inputs should be used to read this information. Figure below shows how to connect alarm
button, door sensor, etc.
