Specifications

35
increase the voltage drop across this resistor to a value that is readable by the
microcontroller. This is typically done on the high side of the load, but it is possible to
also use this method the low side of the load. The charts below detail the advantages
and disadvantages of both low side and high side sensing.
High Side
Low Side
Pros
Cons
Pros
Cons
Current sensor is
directly connected to
the power source,
and can therefore
detect a downstream
failure right away so
corrective actions can
be made
Current sensor must
withstand higher
voltages
Easy to implement,
usually with just an
op amp and a shunt
resistor
Adds resistance to
the ground path
Current sensor won't
increase the
resistance to the
ground
Cheap and very
precise
Figure 26 - Comparison between Placing a Current Sensor on the High Voltage Side of a Load vs. the Low Side
Hall Effect sensors are in general much easier to set up and use, as there is no
soldering required. Just connect the power wire to the battery, run it through the sensor,
and then connect the remaining end to the load. On the down side, these types of
sensors are usually bulky, and must be bolted down to a solid location. On the other
hand, shunt resistor current sensor circuits can be a bit more complex. First, the correct
resistance must be chosen for the shunt resistor, and then the correct amplifier must be
chosen as well. Then the two components must be soldered in series with the load.
These shunt resistor current sensors do however take up much less space, and could
possibly even be implemented directly on the microcontroller PCB.
4.1.8 Displays
Figure 27 - SparkFun LCD Display
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