Atmospheric sensors from the DFRobot Gravity series
The Gravity series of modules includes a large group of sensors measuring basic physical quantities used to determine environmental parameters - temperature, relative humidity and atmospheric pressure. Apart from simple analog sensors (LM35) and digital sensors (the immortal DS18B20), the offer of the well-known manufacturer includes even non-contact sensors (in this role the popular MLX90614 integrated pyrometer). Interestingly, Gravity series of modules includes also special circuits dedicated for temperature monitoring using thermocouples (for this purpose there is integrated converter MAX31855K) and thermoresistors PT100. Particularly interesting are multifunctional sensors, such as BME280 - providing the ability to conduct accurate measurements of temperature, pressure and relative humidity and communicating with an external processor via I2C bus. In the construction of flying machines (e.g. drones) a miniature board with a barometer and a 9-axis MEMS inertial sensor will be a perfect solution - the I2C - DFRobot SEN0252 module also uses the I2C interface for communication, and only 4 wires are needed to connect the board (it has a 4-pin Gravity connector and an appropriate cable is included). The electrochemical ozone sensor SEN0321 is also worth mentioning.
Sensors for monitoring of soil and water conditions
Measurements of physical and chemical quantities carried out directly in the soil, allow for precise monitoring of the conditions of plant development - this is important especially in the case of varieties with high sensitivity to too low or too high humidity of the substrate and its incorrect reaction. The series of DFRobot Gravity modules includes two analogue modules for measurement of soil moisture, working on the basis of its electrical conductivity (Moisture Sensor v2) or capacity (corrosion resistant SEN0193 module, in which the measuring paths are completely soldermasked). The best capabilities in the target applications are provided by a high-end sensor SEN0308 with a hermetic connector and printed millimeter scale, allowing easy verification whether the sensor is located at the appropriate depth in the monitored substrate. For particularly demanding applications, the DFR0300-H analogue water and soil salinity sensor will come in handy - the kit includes a robust, waterproof measuring probe, a converter module, a connection cable and four jars of 12.88 mS/cm buffer solution, as well as a set of necessary mounting hardware.
Gravity system in practice
DFRobot Gravity modules are available with 3- and 4-pin system connectors, compatible with all Gravity ecosystem boards. The 3-pin sensors offer digital (binary, i.e. 0/1) and analog (voltage) outputs, while the 4-pin sensors are most often equipped with an I2C interface, compatible with almost all base boards from the well-known manufacturer. The use of keyed connectors ensures error-free connection of the cable to the sensor PCB, which is important to avoid damage by accidental reversal of power supply polarity. Gravity series contains also numerous executive modules - including motor drivers, modules with relays or even... small DC motors.