Friday, August 25, 2017

Meet The Grove Shield

The Grove Shield is a particularly useful tool for blind or sighted beginners working with Arduino. It’s awesome for quick proof-of-concept projects, introductory Arduino workshops, and for anyone with impaired dexterity or fine motor control issues. The main benefit of the Grove Shield and its family of components is that it saves you from the hassle of wiring each component to ground, power, and its respective input or output pins, simplifying project construction significantly. It also ensures solid connections with snugly fitting plugs and sockets. Only one kind of cable is used for all components, and the plugs have a clear orientation that prevents you from plugging them in backwards.

The Grove Shield from Seeed Studios piggybacks on the Arduino Uno or similar controller’s and allows easy connection to a large number of sensors, actuators, and communication options. In addition to the standard headers, the Grove Shield includes 16 sockets, all of which use the same four-conductor ribbon cables to connect Grove components to analog, digital, I2C, and UART pins on the Arduino. Each socket includes connections to ground and power, so wiring up projects becomes extremely easy. The Grove Shield also includes a Voltage Switch to switch between 5V and 3.3V power, a reset button duplicating the one on the Arduino, and the standard set of 6 male ISP pins. Oh, yeah – it also includes an LED if you’re in to that sort of thing.

A very nice Grove starter kit can be ordered from Amazon for about $45, although it does include a relatively expensive LCD component which blind makers won’t have much use for. Other than that, the starter kit is great and includes a nice variety of components. Additional components can be ordered from Amazon or from Seeed Studios. Note that the starter kit does not include an Arduino.

When you receive your Grove Shield the pins on the back of the board are embedded in a foam pad to protect them from being bent. While getting oriented to the shield we recommend leaving the board attached to the foam or seating the shield on an Arduino. The pins on the bottom of the shield are delicate, and whenever you connect or disconnect the shield from an Arduino you should always be careful to avoid bending pins.

Orienting to the Grove Shield

With the Grove shield and its foam pad on a table in front of you, rotate the board so the Voltage switch and reset buttons are at the top-left corner, and the standard headers run vertically along the left and right edges of the board. The 6 male ISP pins (looking something like a sideways braille cell) should be toward you in the middle of the bottom edge of the shield.

The Voltage Switch faces left at the top edge of the left side of the shield. When the switch is set toward you the shield is set to use 5V power supply. When the switch is set away from you the board receives 3.3V. We have found this switch to be a little delicate, so handle it with care. If it breaks, the board is broken. Just below the switch on the left edge of the board is the reset button (and the LED). Along the top edge of the shield are the 4 analog sockets. located between the two standard headers are 12 other sockets arranged in a 3X4 grid like a telephone keypad.

Analog Sockets

The analog sockets line the top edge of the shield. From left to right they are A0, A1, A2, and A3.

I2C Sockets

The I2C sockets are the left-most column of 4 in the array of 12 sockets. Using the telephone keypad analogy, the I2C sockets correspond to 1, 4, 7, and *.

Digital and UART Sockets

The digital sockets are the top-three sockets in the right-hand column of the main group of twelve, as well as the center column of 4 sockets. The UART socket which uses digital pins 0 and 1 is the bottom right socket in the group of twelve (the pound sign in our keypad analogy).

Moving up the column from the UART socket, the sockets are D2, D3, and D4. Starting with the bottom-center socket and moving up, sockets are D5, D6, D7, and D8.

Primary and Secondary Connections

Somewhat confusingly, each analog and digital socket actually connect to two different pins – a primary and a secondary. Most components only use one of these connections, but some use both. Above we have listed only the primary connections, but each socket also connects to the next pin as a secondary connection. In other words, the secondary connection for A0 is A1, the secondary connection for A1 is A2, and so on. The digital connections follow the same pattern, with the secondary connection for D2 being D3, etc. In general, you only need to worry about the primary connections.

Orientation to Grove Sockets and Plugs

All the Grove sockets have a basic rectangular profile ( approximately 1/2X1/4 inch), and they are all oriented on the board with the longer axis running from left to right. Each socket has a notch approximately ¼ inch wide cut in the center of the two longer sides. One side has a much deeper notch than the other, and we will call the side with the deeper notch the “front” of the socket. You may have already noticed that the analog sockets are rotated at 90 degrees to the other 12 sockets. In other words, analog sockets have their fronts facing up with plugs entering from the edge of the board, while the other twelve have their fronts facing you with plugs entering from above. Each Grove component also has the exact same socket with a front and back.

The ribbon cables that connect the Grove components to the shield have an identical plug at each end. Each plug has a flat side which goes toward the back of the socket, and a side with two long parallel ridges which goes toward the front of the socket. At the very end of each plug are four holes which connect with corresponding pins inside the sockets. These holes correspond to the four wires of the ribbon cable. When the cable is plugged in to a socket with the front of the socket facing you, the wires, from left to right are primary pin, secondary pin, power, and ground, and are colored yellow, white, red, and black respectively. This is extremely useful to know if you want to integrate Grove and non-Grove components.

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