6.3 Capacitive Touch Slider
A touch slider utilizing the capacitive touch capability of the EFM32 is located on the bottom side of the board. It consists of four inter-
leaved pads which are connected to PB6, PB15, PB4 and PA7.
PB6 (CSEN APORT2Y/1X CH22)
PB15 (CSEN APORT2X/1Y CH31)
UIF_TOUCH0
UIF_TOUCH1
EFM32
Capacitive Touch Slider
UIF_TOUCH2
UIF_TOUCH3
PB4 (CSEN APORT2Y/1X CH20)
PA7 (CSEN APORT2X/1Y CH7)
Figure 6.3. Touch Slider
The capacitive touch pads work by sensing changes in the capacitance of the pads when touched by a human finger. Sensing the
changes in capacitance is done by setting up the EFM32's analog capacitive sense peripheral (CSEN).
6.4 Si7021 Relative Humidity and Temperature Sensor
The Si7021 I
2
C relative humidity and temperature sensor is a monolithic CMOS IC integrating humidity and temperature sensor ele-
ments, an analog-to-digital converter, signal processing, calibration data, and an I
2
C Interface. The patented use of industry-standard,
low-K polymeric dielectrics for sensing humidity enables the construction of low-power, monolithic CMOS Sensor ICs with low drift and
hysteresis, and excellent long term stability.
The humidity and temperature sensors are factory-calibrated and the calibration data is stored in the on-chip non-volatile memory. This
ensures that the sensors are fully interchangeable, with no recalibration or software changes required.
The Si7021 is available in a 3x3 mm DFN package and is reflow solderable. It can be used as a hardware- and software-compatible
drop-in upgrade for existing RH/ temperature sensors in 3x3 mm DFN-6 packages, featuring precision sensing over a wider range and
lower power consumption. The optional factory-installed cover offers a low profile, convenient means of protecting the sensor during
assembly (e.g., reflow soldering) and throughout the life of the product, excluding liquids (hydrophobic/oleophobic) and particulates.
The Si7021 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring humidity, dew-point, and temperature,
in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms.
The I
2
C bus used for the Si7021 is shared with the Si7210 hall-effect sensor. To use the sensor, PB3 must be set high, which also
powers the Si7210. When enabled, the sensors' current consumption is included in the AEM measurements.
SENSOR_ENABLE
PI4 (I2C2_SDA #7)
PI5 (I2C2_SCL #7)
PB3 (GPIO)
SENSOR_I2C_SDA
SENSOR_I2C_SCL
VDD
EFM32
Si7021
Temperature
& Humidity
Sensor
Figure 6.4. Si7021 Relative Humidity and Temperature Sensor
Please refer to the Silicon Labs web pages for more information:
http://www.silabs.com/humidity-sensors
UG287: EFM32 Giant Gecko GG11 Starter Kit User's Guide
Peripherals
silabs.com
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