If you are looking for a HAT or Hardware Attatched on Top for your Raspberry Pi (RBPi) that has motor and touchscreen drivers, integrated sensors and interfaces with 5V devices, the Explorer HAT is for you. Standard add-on board HATs allow the Linux-ready SBC, the RBPi, to configure its GPIO signals and drivers to control and use external devices.

Pimoroni has two models of HATs for the RBPi – the Explorer HAT and the Explorer HAT Pro. They support the HAT standard set by the Raspberry Pi Foundation, matching requirements for the RBPi 2 Model B, including the first-generation Model B+ and Model A+ boards as well.

To integrate inputs from 5V Trinkets or Arduino boards, the Explorer HAT offers four buffered 5V inputs. In addition, four powered 5V outputs on the board can supply 500mA to drive stepper motors, relays and or solenoids. The Explorer HAT also has a mini-breadboard, four capacitive touchpads, four LEDs and four capacitive alligator clips.

In addition to all the above features of the Explorer HAT, the Explorer HAT Pro has analog inputs and two motor drivers in H-bridge configuration to drive micro-metal geared motors and similar. The Explorer HAT Pro also comes with plenty of 3v3 features from the GPIO. However, these are unprotected.

According to the specifications defined for the Explorer HAT, each board has four inputs each 5V tolerant including 5-channel buffers with 2-5V support. There are four 5V powered Darlington-array outputs capable of 500mA per channel, limited to 1A total. The front edge of the board has four capacitive touch pads along with four LEDs, controlled independently. Including the mini-breadboard, the dimensions of the Explorer HAT are 65x56x13mm.

The Explorer HAT Pro version adds four analog inputs including two bi-directional motor drive outputs of the H-bridge type capable of handling 200mA per channel. It supports soft-PWM for full speed control. Additionally, there are the unprotected 3V3 GPIO features.

Compared to the Pibrella, another board made by Pimoroni, both the Explorer HAT and the Explorer HAT Pro share many similarities, but also add a lot more besides. For example, the analog and digital inputs are a great help, especially since you can connect inexpensive and simple sensors such as the TMP36, while taking advantage of the built-in ADC.

The capacitive touch buttons of the Explorer HAT not only allow interfacing with connected components, but also allow independent working. For example, you can send a tweet, an email or a text message by simply tapping one of the buttons. There are many other possibilities with these capacitive touch buttons. You can connect crocodile clips and brass contacts for using fruits as buttons. Of course, the software will have to be tweaked somewhat to get the proper sensitivity.

Plugging HATs on the RBPi invariably causes loss of access to some GPIO pins. The Explorer HAT breaks out the most useful pins from the GPIO, making them easily accessible. Pimoroni provides intuitive Python libraries and a built-in tutorial for all to use.
Overall, both the Explorer HAT boards are a great value for money not only for kids playing and learning to interface with the RBPi, but also for grown-ups.