How can I use the LESENSE module to scan resistive sensors in EM2?
Resistive sensors are the most basic type of analog sensors. They display a change in their electrical resistance, and produce a voltage signal equivalent to the measured physical quantity when placed in an electric circuit. Commonly-used resistive sensors include potentiometers, light sensors (photo resistors), or temperature sensors (thermistors). Resistive sensor reading with an EFM32 device can be done using either one or two pins.
The LESENSE module is a highly-configurable peripheral that allows interaction with a wide range of sensors. It can control channel pins or a DAC for sensor voltage excitation and the ACMP mux for sensor reading. When the LESENSE interacts with sensors, there are two main phases: excitation and measurement. These can use either the low or the high frequency clock as the time base, with the duration being adjustable by the number of clock cycles.
With EFM32, resistive sensors can be read using the LESENSE module using only one LESENSE pin. To read a resistive sensor using two pins, the setup must have alternative excitation pins (LES_ALTEXn) which are used to excite the sensor.