ZIO, Motherboard User Manual
Rev. 2.0
Zilogic Systems
Page 13
potentiometer is moved from pin 1 to pin 3, the raw value varies from 0 to N
max
. Where N
max
is
given by the following formula.
N
max
= (0xFFFF x R
max
) / (R
max
+ 10K)
Here,
• R
max
is the maximum resistance of the potentiometer
• 10K is the internal pull up resistor on the Sensor signal. For more details refer ???.
For a 10K potentiometer, N
max
= (0xFFFF x 10K) / (10K + 10K) = 0x7FFF
Connecting a Resistive Sensor.
Sensors whose resistance varies with the parameter being
measured are called resistive sensors. Examples of resistive sensors are Light Dependent Resistor
(LDR), thermistor, etc. These sensors can be directly connected between the
Sensor
signal and
GND
. As the parameter being measured varies, the resistance varies accordingly, and the raw value
(N) produced is given by the following formula.
N = (0xFFFF x R) / (R + 10K)
Here,
• R is the resistance of the sensor
• 10K is the internal pull up resistor on the Sensor signal. For more details refer ???.
An example circuit, using the LDR, is shown below.
4.2. Voltage Sensors
Voltage measurement, -3V to +3V.
Though the ADC input range is 0 to 3V, it is possible to
measure voltages between -3V and +3V using a simple circuit. The circuit diagram is shown in the
figure below.
