In this article we look at another digital humidity sensor – this time its the SHTC1 and we will connect it to a raspberry Pi
The SHTC1 is a digital humidity sensor designed especially for high-volume consumer electronics applications. This humidity sensor is strictly designed to overcome conventional limits for size, power consumption, and price-performance ratio, in order to fulfill the current and future requirements of the consumer electronics market.
Sensirion’s CMOSens® technology offers a complete sensor system on a single chip, consisting of a capacitive humidity sensor, a band-gap temperature sensor, analog and digital signal processing, A/D converter, calibration data memory, and a digital communication interface supporting I2C fast mode. The ultra-small, 2 × 2 × 0.75 mm3 DFN package enables applications to be placed in even the most limited of spaces. The sensor covers a humidity measurement range of 0 to 100 %RH and a temperature measurement range of –30°C to 100°C with a typical accuracy of ±3 %RH and ±0.3°C.
The operating voltage of 1.8 V and an energy budget below 1 µJ per measurement make the SHTC1 suitable for mobile or wireless applications running on the lowest power budgets. With the industry-proven quality and reliability of Sensirion’s humidity sensors and constant accuracy over a large measurement range, the SHTC1 humidity sensor offers an unprecedented price-performance ratio. Tape and reel packaging together with suitability for standard SMD assembly processes make the SHTC1 predestined for high-volume applications.
|Supply voltage||1.8 V|
|Power consumption||2µW (at 1 reading per second in low power mode)|
|Measuring range (RH)||0 – 100% relative humidity|
|Measuring range (T)||-30 to +100°C (-22 to +212°F)|
|Response time (RH)||8s (tau63%)|
|Connecting wire||Free shipping Dupont line 120pcs 20cm male to male + male to female and female to female jumper wire|
|sensor shield||Expansion IO Board Sensor Shield|
Enable I2C on Your Raspberry Pi
$ sudo raspi-config $ sudo reboot $ ls -l /sys/bus/i2c/devices # This should output: i2c-1
If you want to verify that the sensor is wired run i2cdetect -y 1 0x70 0x77. If everything is fine, you should see it listed at address 0x70
Now you need to load the SHTC1 driver
$ sudo modprobe shtc1 $ echo shtc1 0x70 | sudo tee /sys/bus/i2c/devices/i2c-1/new_device $ ls /sys/bus/i2c/devices/1-0070/
To read the current temperature:
$ cat /sys/bus/i2c/devices/1-0070/hwmon/hwmon1/temp1_input 19479
…and the relative humidity:
$ cat /sys/bus/i2c/devices/1-0070/hwmon/hwmon1/humidity1_input 53398
You can see this in the following screen capture