Hardware - Sensor Groves

Seeed makes several dozen (!) Sensor Groves. We only have a few of them, but we're planning to get more. Suggestions welcome!

Button

The button is actually an SPST (single pole, single throw), momentary contact switch. The first output line is connected to GND (LOW) through a 10K Ohm "pull-down" resistor. Pressing the button connects the line to VCC (HIGH) through a 100 Ohm "pull-up" resistor.

This Grove is normally cabled to a digital port. The body of push button is a tiny box, about 0.2" square and 0.1" tall. The head of the button is circular, about 0.1" in diameter. The button and port socket are on the top of the Grove.

Note: The Seeed wiki (incorrectly) lists the Button as an Actuator.

Encoder

The incremental rotary encoder opens and closes a pair of contacts (in an alternating, phase-shifted manner) as the shaft is turned. This makes it possible to determine how many positions (to the left or right) the shaft has been turned.

This Grove is normally cabled to a digital port. The body of the encoder is a metal box, about 0.4" square and 0.3" tall. The shaft is also metal, about 0.5" long, with a flat side for the top 0.4". A set of mounting threads, about 0.3" long, connects the shaft to the box. The encoder is mounted on one side of the Grove; the port socket is on the other.

Pushing the shaft in (toward the circuit board) closes a contact for a push button. Because the Grove cable only has four lines, this lead is not connected by default. We hooked this to a pin lead, so that it could be plugged into a digital input socket.

Light Sensor

This light sensor reports the intensity of incoming light as an analog signal, using a photodiode, photoresistor, or other light-sensitive device.

This Grove is normally cabled to an analog port. The sensor is a plastic cylinder with a domed top, about 0.2" tall and 0.2" in diameter. It stands up about 0.4" from the Grove circuit board. The sensor and port socket are on the top of the Grove.

Note: Seeed makes various versions and configurations of this device. YMMV.

Rotary Angle Sensor

The rotary angle sensor uses a 10K Ohm potentiometer, commonly called a "pot". This is a fixed resistor, shaped as the arc of a circle, with a sliding tap. Rotating the shaft moves the tap from the grounded end to the powered end, so the returned voltage is somewhere in between the two values.

This Grove is normally cabled to an analog port. The sensor body is a metal box, about 0.4" square and 0.3" tall. The shaft is plastic, about 0.5" long, with a set of parallel ridges running up the top 0.3". The sensor and port socket are on the top of the Grove.

Sound Sensor

The sound sensor uses an electret microphone (and associated circuitry) to capture analog samples of sound.

This Grove is normally cabled to an analog port. The body of the microphone is a squat cylinder, about 0.2" tall and 0.4" in diameter, with cloth glued to the top. The microphone and port socket are on the top of the Grove.

There is also a rectangular integrated circuit (about 0.2" by 0.1"). This contains an LM358 dual op amp (operational amplifier) which processes the electret's output into a scaled, linearized analog voltage. It may also do low-pass filtering, to reduce the possibility of aliasing when the Arduino can't sample fast enough to match the incoming frequencies.

Temperature Sensor

The temperature sensor reports the ambient temperature as an analog signal. This Grove is normally cabled to an analog port. The sensor and port socket are on the top of the Grove.

The sensor is a thermistor (a tiny, thermally-sensitive resistor), labeled NTC (for "Negative Temperature Coefficient" sensor). Next to it is a larger, rectangular integrated circuit (about 0.2" by 0.1"). This contains an LM358 dual op amp (operational amplifier) which processes the thermistor's output into a scaled, linearized analog voltage.

Touch Sensor

The touch sensor emits an RF (radio frequency) signal and detects the load. When it is touched by (say) a fingertip, it outputs a digital (HIGH) signal.

This Grove is normally cabled to a digital port. Some paint on the bottom of the Grove has been removed to reveal a 0.5" metallic circle. The port socket is the only obvious part on the top of the Grove.

Resources


This wiki page is maintained by Rich Morin, an independent consultant specializing in software design, development, and documentation. Please feel free to email comments, inquiries, suggestions, etc!

Topic revision: r4 - 17 Apr 2017, RichMorin
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