Pimoroni Inventor HAT Mini Review: Great for Making Robots
Inventing is never easy, but Pimoroni seems to be on a winning streak. The company’s newest board, his $24 Inventor HAT Mini, is an add-on board designed following the “pHAT” board design philosophy. Raspberry Pi Zero 2W and their predecessors.Also available for Model B raspberry pi,Such raspberry pi 4When using header extensions.
This little board has various outputs for servos, GPIOs, motors, sensors, serial communication and of course 8 bright RGB LEDs.
Are you a potential candidate for our list? Best Raspberry Pi HATTo learn it and learn more about what this board can do put it on the bench and see how it performs.?
Inventor HAT Mini Specifications
GPIO pins | 4 x Hobby Servo Pins |
4 x general GPIO pins | |
motor controller | DRV8833 Dual H-Bridge Motor Driver |
2 x JST-SH connectors | |
2 x 2-pin motor terminals (on the back of the board) | |
audio | MAX98357 3.2W I2S Mono Amplifier |
2 pin speaker connector | |
LED | 8x WS2812/NeoPixel RGB LEDs |
input | user button |
GPIOs | Pass-through 40-pin header |
1 x QW/ST (Stemma QT / Qwiic) connector | |
size | 65×30.5×15.5mm |
Setting up Inventor HAT Mini
The Inventor HAT Mini has different header connections than most HATs (except the Sense HAT). The HAT can pass through the GPIO pins so you can connect another board on top of it. A very long header would be required to allow this. Also, for added stiffness he conveniently uses M2.5 spacers.
If using the Inventor HAT Mini alone, slide the HAT onto the Raspberry Pi’s GPIO. If you are a Raspberry Pi Zero user, no problem, but if you use other Raspberry Pi, please pay attention to the clearance of QW/ST and audio connections or use expansion headers. The reason for the passthrough is the Nuvoton MS51TC0AE microcontroller that provides the interface for servo pins and GPIO pins. This frees up a lot of pins on the Raspberry Pi to allow another board to be stacked on top of the Inventor HAT Mini.
Software installation is detailed in the Pimoroni documentation. Github repository. It’s not as straightforward as his other Pimoroni boards that use an automated installer, but the instructions were clear and it didn’t take me long to complete the installation.
The pins present on the board are grouped into two sections. The first is for hobby servos such as the SG90. Hobby servos have specific pinouts, signal, voltage, and GND (SVG), and Inventor HAT Mini accommodates this because each servo channel has its own SVG pinout.
Just make sure the GND (black) connector is on the GND pin and you are good to go. It doesn’t matter if you’re wrong. I was wrong and nothing happened. Just fix the connection and everything will be fine. His second bank of GPIO pins is his 4 general purpose pins that also follow his SVG pinout. Each signal pin is both a digital pin and an analog pin, and this versatility means it can be used to blink LEDs, trigger relays, or read analog electronics. The user button is right next to his GPIO pin and this button is a simple input to the user project.
Just above both banks of GPIO pins are eight WS2812 NeoPixels. These tiny LEDs are easily controlled using a custom Python module and can be controlled as a group or individually.
Now let’s shift our focus to custom connections around the board. At the top right is the QW/ST connector.This is Pimoroni’s name Stemma QT/Qwiic Connectors This connector is compatible with all components that use it.I have a list of Best Stemma QT / Qwiic Addons You can purchase them to add functionality to your board. I have connected a BME688 temperature and humidity sensor and installed the corresponding Python module. Within seconds, the office temperature started scrolling down the screen.
Underneath the letters A and B are two 6-pin JST-SH connectors for use with compatible DC motors. These motors look like typical 6V DC micro gear metal motors, but have JST-SH 6 pin connectors that can only be inserted one way. These connectors are useful, but you have to agree with the system to make them work. If you already have a common 2-pin DC motor in stock, you’ll see the corresponding connections on the underside of the board. At first glance, I missed these connectors.
Also on the underside of the board is a 2-pin audio connection for a small speaker. The MAX98357 3.2W I2S mono amplifier is capable of producing good quality audio. This is not a THX certified sound system, but a cute way to make clear noise.
For advanced users there are a series of additional unpopulated headers on each side of the board. There is a header for serial communication (TX / RX) on the top of the board, and it can also be used with 3.3V compatible ultrasonic distance sensors (HC-SR04P or HC-SR04+). Note that you can use a different set of headers to power the board, but only one power supply should be used at a time. If you only want to power the motors/servos, disconnecting leaves the Pi disconnected from the motor power.
Using Inventor HAT Mini
The Python modules that come with Inventor HAT Mini are of normal quality. I’ve been using Pimoroni boards since 2013 (pibrera first) and while I can see the quality maturing, the Pimoroni’s attention to detail is still sharp. Its Python module abstracts the complexity for learners and provides a quick means of getting their projects done.
If you are new to coding, electronics or robotics and encounter a learning barrier, you will easily lose confidence and quit. Abstracting complexity means that learners can “hit it right away” and find themselves growing in confidence as they tackle the next challenge. I like the board layout. Admittedly, the positioning of the Stemma QT and audio connections can be tricky when used with the Raspberry Pi Model B, but there’s nothing an expansion header can’t fix. Connectivity options have been carefully selected to maximize the form factor. I would have liked to see a capacitive touch input like the Explorer HAT Pro on our list of Best HATs for Raspberry Pi, but it takes up too much space.
The control of the motors and servos is excellent, as seen in other Pimoroni robot-centric products, largely due to the influence of Dr. Chris Parrott, product engineer at Pimoroni. Stemma QT (QW/ST) is always welcome for a quick and easy connection. And who can resist a tiny RGB LED on a board?
Conclusion
Pimoroni’s $24 Inventor HAT Mini appears to be the spiritual successor to the company’s long-running Explorer HAT series of boards. This is evident to me after using the Explorer HAT Pro for almost 9 years. The board is well designed, the features are well thought out and the software is easy to use. If you are a Raspberry Pi Zero user, this little board is perfect as a robot controller. Raspberry Pi model 3B/4B users will have no problem with USB/Ethernet clearance once they purchase the expansion headers. It’s a very fun board to use.