DFRobot Gravity - one system for thousands of applications
A huge advantage of the Gravity system is the compatibility of the modules with a wide range of evaluation boards and control modules. The main product dedicated to Gravity modules is IO Expansion Shield, dedicated to work with original Arduino modules (e.g. Arduino UNO or Arduino Mega 2560), as well as all kinds of "clones" and boards compatible with well known hardware ecosystem of this Italian manufacturer. What's more, the Gravity modules provide a convenient connection using small raster connectors, for which ready-to-use connection cables with BLS type plugs are available. The connectors on the side of the modules prevent reverse plugging in (thanks to a special design with the so-called key), which reduces the risk of damage by the reverse polarity of the supply voltage. Products from Gravity family are available in three versions: digital (with 3-pin connector), analog (also with 3-pin connector) and digital (with 4-pin connector, supporting two separate digital lines or I2C interface).
DFRobot Gravity series audio transducers
The Gravity system does not lack both the simplest modules for generating audio signals, as well as more advanced functional blocks, providing the ability to play recordings recorded in digital form. To the first group we should include the DFR-11263 module with a simple passive buzzer - because the converter is devoid of a built-in generator, found in many buzzers available on the market, the user can independently select the pitch of the sound, providing the control input with a digital waveform of the set frequency. It is worth to use the built-in microcontroller hardware timer for this purpose, which will allow to generate the sound in a way that does not take the processing power of the processor. The DFR-05501 module, on the other hand, is equipped not only with a miniature electrodynamic speaker, but also an integrated amplifier type 8002B and a potentiometer, used for manual volume control. Also in this case, a digital PWM signal can be used to control the module, although the structure of the circuit also allows for the supply of an analog audio signal.
Gravity actuators with DC motors
The Gravity module range includes various types of modules that allow experimentation with the use of direct current (DC) motors. The simplest of them is DFR-05965 - on a small PCB measuring only 52 x 26 mm there is a miniature windmill with a 5-volt motor, which thanks to the built-in transistor can be easily controlled directly from the output of Arduino or any other microcontroller. An even smaller solution for building a simple windmill is the DFR-03559 module, containing a fast DC motor (with speed up to 15 000 rpm) and PCB dimensions of just 36 x 27 x 13 mm. For signaling events in mobile and wearable devices, on the other hand, the DFR-11287 module with a miniature vibration motor will come in handy. A particularly interesting example from DFRboot's offer is a wire (peristaltic) pump with the DFR-11460 catalog designation. The built-in controller allows for simple control using just a single pin of the microcontroller, and the isolation of the pumped liquid flow from the mechanics of the pump itself significantly extends the module's range of applications in relation to simple water pumps used, for example, in potted plant irrigation. The peristaltic pump provides the possibility of very precise dosing of liquid, in a way not possible with simple membrane pumps.