Adafruit Crickit for Circuit Playground Express review

By Ben Everard. Posted

The Creative Robotics & Interactive Construction Kit (Crickit) for Circuit Playground Express (CPX) is an add-on board for the CPX for interfacing with physical hardware. It adds a range of hardware controllers, including two motor controllers (5 V, 1A), four servo connections (analogue or digital), four high current (500 mA) outputs, a class-D 3 W audio output, and four capacitive touch pins. Together, these enable you to control almost any physical hardware you may want (the only major limitation is for stepper motors – some will work with the Crickit, but not all). All of these items are designed to run at 5 V.

As microcontroller boards go, the Circuit Playground Express isn’t naturally suited to add-on boards. Almost all other small processing boards have a set of male or female headers that you can easily push an expansion board onto. The CPX, on the other hand, has a circular array of larger holes designed for alligator clips. The Crickit gets around this with six bolts that both hold the CPX in place and create an electrical connection.

Like the CPX, the Crickit eschews the traditional pin headers of many circuit boards. It’s designed to be included in things – be they robots or some other physical computing device – and as such, most of the connections are robust. Most are screw terminal blocks, which are both easy to connect/release and reliable for connections on bits that move and bounce around. The servo connections are male headers that most servos can plug straight into, the signal connections are male headers, and the capacitive touch retains the large circular connections of the CPX.

crickit2

There is a micro USB jack, but this is for debugging the SeeSaw controller that handles the input/output on the Crickit. Power comes via a 5 V 2.1 mm jack connector that can take up to 4 A. Be aware that while 9 V jacks such as those used to power Arduinos will fit, they will trip the eFuse, which only accepts connections below 5.5 V. There’s a mounting hole in each corner of the octagonal PCB, which should give you plenty of options for securely attaching it in your project.

The Crickit can be programmed from MakeCode, Circuit Python, and Arduino. The MakeCode support is still in beta but is available through makecode.adafruit.com/beta, using the Advanced > Extensions block and searching for Crickit. This allows you to drag and drop controls to the motors, servos, signals, and touch. Circuit Python and Arduino support comes via the SeeSaw library, which handles the I2C interface between the CPX and the various peripherals.

When we originally tested the CPX, we were impressed by the wide range of peripherals on board, and the way it ‘just worked’ for a wide range of things. The Crickit brings this same approach to controlling physical hardware. Sure, you probably won’t need all the connections in one project, but you might need most of them at some point in the next few projects, and having them all in one place makes it easier to get started quickly.

The one big caveat with the CPX and Crickit combination is that there’s currently no easy way of communicating with it via WiFi or Bluetooth. Fear not, though. The Crickit is coming soon to the Feather line of boards which includes a wide range of different microcontrollers and numerous connection options (this is expected shortly after this magazine goes to press and might be available by the time you read this). There’s also a planned version for the Raspberry Pi.

Overall, if you’re looking for a board that works with a wide range of input and output options, it’s going to be hard to beat the Crickit. It’s a generalist board for all us tinkerers who never quite know where the project is going when it starts – with all those output options, you’re bound to be able to add on the extra feature that you didn’t think of when you started, but now absolutely need.

Seesaw

SeeSaw is a framework developed by Adafruit to use a microcontroller as a coprocessor to another microcontroller via I2C to add more peripheral options. This only uses the two pins necessary for the I2C protocol, and you can connect multiple I2C devices to a single I2C bus, so it allows you to add a lot of peripherals without taking many resources from the original microcontroller.

On the Crickit, there’s an ATSAMD21 microcontroller that handles all the extra hardware. This means that the processor on the CPX doesn’t get bogged down with the details of sending signals to the servos, motors, etc. It just sends a signal to the Crickit telling it what should happen and the Crickit handles the rest. You can think of it a little like a super-powerful I2C port expander.

The Crickit isn’t the first board to use SeeSaw. The Adafruit SeeSaw board
(hsmag.cc/XIlrnR) connects via I2C and has analogue, digital, and PWM GPIOs. This board works with Android-compatible boards, Circuit Python, and even Python on the Raspberry Pi.

Adafruit $29.95 Adafruit.com

Verdict

A cracking board for adding a wide range of hardware capabilities to your CPX

9/10


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