Outdoor temperature and humidity sensor
Here is a temperature and humidity sensor equipped with an I2C interface, all enclosed in a nice case. This sensor contains a DS18B20 temperature sensor and a humidity sensor with a capacitive effect.
The case also integrates a small micro-controller which performs the readings and offers an I2C interface for reading the values (calibrated and ready to use values).
The great thing about this sensor is that it's enclosed in a solid case and supplied with a fixing support. This is what makes this product significantly superior to other sensors that you can mount on a card.
This sensor isn't classified "weatherproof" (not resistant to severe weather, not IP67).
It will make measurements where there is wind, rain, undead, etc much better than sensors mounted directly on a board. Its I2C interface makes it easy to interface with a micro-computer which, for its part, will find it difficult to accommodate the delicate management of time imposed by DHT sensors.
Simply connect the red wire to the 5V power supply, the ground/GND to the black, the yellow to the I2C data pin and the white to the I2C clock pin.
It isn't possible to change the I2C address of the sensor. So you can only mount one sensor on the I2C bus (unless you're using an I2C TCA9548A multiplexer).
Two pull-up resistors of approximately ~10Kohm are required to use this sensor. Connect a resistor between the SDA and the power line AND another resistor between the SCL line and the power line. The pull-up resistors are not included!
This sensor has a memory in which it stores the result of the last measurement (therefore NOTHING on the very first power-up). When the sensor is reactivated after a long pause, it first returns the last reading in memory... reading which may no longer be relevant!
A technique for easily obtaining an updated statement is to:
- Read and ignore the data returned.
This allows the sensor to come out of standby mode if it was in energy saving mode.
- Wait 2 seconds.
- Do a second reading to get fresh data.
- Power supply and I/O lines: 3.5 to 5.5V
- Max current: 10 mA (using during conversion, therefore during data request)
- For a reading of 0-100% humidity with an accuracy of 2%
- For temperature reading -20 to 80°C, typical accuracy ±0.1°C
- Refresh rate: 0.5 Hz (once every two seconds)
- Body size: 98mm x 16mm in diameter
- 4 wires, about ~50 cm de long
- Weight: 82.64g
- The board uses the I2C address: 0x5C (7 bits).
AM2315 data sheet (pdf)