Heikki Leivo and Matti Koljonen are currently working together to develop a miniature autonomous electric boat, which they are calling Leviathan. The boat is made of polystyrene foam, uses brushed DC motors and servos for movement, and is controlled by a Raspberry Pi, which reads data from GPS and a MinIMU-9 inertial measurement unit for navigation. Leviathan is equipped with a camera and also features a D24V6ALV step-down regulator for powering servos and other electronics. The boat is also controllable over WiFi.

The electronics inside Leviathan.

Matti and Heikki plan for their vehicle to be able to run pre-defined routes, capture photos, and record video, among other things. You can learn more about Leviathan on its website.

Related products

	Raspberry Pi Model B+
	Pololu Step-Down Voltage Regulator D24V6ALV
	MinIMU-9 v3 Gyro, Accelerometer, and Compass (L3GD20H and LSM303D Carrier)

When the Raspberry Pi Model B+ was released last month, one of the most exciting features for us was the availability of a second hardware PWM output that can be used for motor control (previously, only a single hardware PWM output was available on the Model A and Model B). Two is a really useful number for robot builders, since that’s what you need for a basic robot platform, so we thought it would be a great time to make a dual motor driver kit for the Raspberry Pi.

The new Pololu DRV8835 Dual Motor Driver Kit for Raspberry Pi B+ is a minimal, low-cost motor driver expansion board based on the Texas Instruments DRV8835 dual motor driver, one of our favorite motor driver chips for small robots like the Zumo because of its excellent combination of size, cost, and performance. We carry a basic breakout board for this chip and just released an Arduino shield based on the DRV8835 last week.

Pololu DRV8835 dual motor driver kit (assembled) on a Raspberry Pi Model B+.

When assembled, the board plugs into a 2×17 block of pins on the Raspberry Pi GPIO header. Power and motors are connected to a separate block of pins, and you can use the included terminal blocks for easier wiring. The board takes an input voltage of 2 V to 11 V and provides two bidirectional motor channels capable of 1.2 A continuous or 1.5 A peak. You can also reconfigure the board for a single channel with twice the current.

Bonus feature – power your Raspberry Pi from your motor supply!

The Raspberry Pi requires a regulated 5 V supply, which is usually provided via the Micro-B USB power port. This is fine for a stationary setup, since you can just use a USB wall power adapter. On a battery powered Raspberry Pi-based robot, however, you need to somehow incorporate your own 5 V regulator capable of supplying about 500 mA. To help simplify your project, the motor driver kit includes a connection point for a three-pin regulator with the standard VIN-GND-VOUT pinout.

In the picture below you can see a complete setup using the motor driver board and our Step-Up/Step-Down Voltage Regulator S7V7F5 to drive two Pololu plastic gearmotors and power the Raspberry Pi from a set of four AA NiMH cells. This regulator is a good match for the range of input voltages of the DRV8835, though below about 4 V you might need something with higher current capability.

Driving motors with an assembled Pololu DRV8835 Dual Motor Driver Kit on a Raspberry Pi B+. A step-up/step-down regulator provides 5 V to the Raspberry Pi.

For more information, including schematics, pinout diagrams, and example Python code, see the product page.

Related products

	Pololu DRV8835 Dual Motor Driver Kit for Raspberry Pi
	Raspberry Pi Model B+
	DRV8835 Dual Motor Driver Carrier

The Raspberry Pi single-board computer has been around for a little over two years in its original Model A and Model B versions, and in that time, it’s become a very popular platform for electronics experimentation. With many of the same capabilities as a regular desktop or laptop PC, but at a small fraction of the size and cost, the Raspberry Pi offers features like network connectivity and significant processing power for robots and other electronics projects.

Raspberry Pi Model B, Revision 2.0, top view.

Raspberry Pi Model B+, top view.

We’re now selling the new Raspberry Pi Model B+, which improves on the Model B in a number of ways:

• More GPIO pins are available on a 40-pin header; the Model B has a 26-pin GPIO header.
• The number of USB host ports has been doubled to four.
• Switching regulators lower the power consumption of the Model B+ by 0.5 W to 1 W compared to the Model B (which uses linear regulators), while audio is improved by a dedicated low-noise power supply.
• A much smaller microSD card socket replaces the previous full-size SD card socket.
• Audio and composite video output are combined on the 3.5 mm jack, and many of the connectors extend much less past the edge of the board (as does the inserted microSD card).
• Four mounting holes provide more flexibility in mounting the Model B+.

We’ve seen our customers build lots of cool projects with the Raspberry Pi, including a wirelessly-controlled Zumo robot with a video camera and a robotic ping-pong ball collector. We look forward to seeing what you’ll do with the Model B+!

Related products

	Raspberry Pi Model B+
	Raspberry Pi Model B, Revision 2.0

This week I released version 2.0.0 of minimu9-ahrs, an open-source demo program that runs on the Raspberry Pi, reads data from a MinIMU-9 via I²C, and uses the readings to calculate the orientation of the IMU. The new version adds support for the MinIMU-9 v3. The program now supports all past and present versions of the MinIMU-9.

The original version of minimu9-ahrs was released back in 2012, along with ahrs-visualizer, a program for displaying the orientation in 3D. For more background, you can see my blog post about minimu9-ahrs from 2012 or read the Raspberry Pi blog post about it from June 2014. The video below shows minimu9-ahrs and ahrs-visualizer working together:

Version 2.0.0 of minimu9-ahrs also includes some other changes:

In this new version, the raw accelerometer readings that you can get using the --mode raw option have basically been multiplied by 16 from what they were before. We made this same change to our LSM303 Arduino library when we added support for the LSM303D. The reason for this change is that before the MinIMU-9 v3, all the MinIMU-9 accelerometers were 12-bit, with the lower 4 bits of the output registers being unused, so we always shifted the readings to the right by 4 bits to get rid of the unused bits. The LSM303D in the MinIMU-9 v3 has a 16-bit output, so shifting its readings to the right by 4 bits would be inappropriate. However, it is nice for the raw accelerometer readings to have the same scale regardless of which accelerometer you happen to be using, so we chose to stop shifting the output of any of the accelerometers. All the accelerometers are configured to have a full-scale range of ±8 g by minimu9-ahrs, so a reading of 4096 will always correspond to about 1 g. This change should not affect most users, but it is not backwards-compatible, so, following semantic versioning, I incremented the major version number from 1 to 2.

The Debian package that I made for minimu9-ahrs version 2.0.0 uses the armhf architecture instead of armel (which was used for previous versions), so you can easily install it on a Raspberry Pi running Raspbian. I also made a new version of ahrs-visualizer that has an armhf package. If you are not using a Debian-based distribution like Raspbian or you are not using the armhf architecture, you can still compile the programs from source.

With this new version of minimu9-ahrs and our recent big price reduction of Pololu IMUs (which made the MinIMU-9 less expensive than a Raspberry Pi), now is a great time to start experimenting with these state-of-the-art MEMS sensors.

Related past posts

• Big price reduction of Pololu MEMS sensor carriers and IMUs
• New product: AltIMU-10 v4 gyro, accelerometer, compass, and altimeter

Related products

	AltIMU-10 v3 Gyro, Accelerometer, Compass, and Altimeter (L3GD20H, LSM303D, and LPS331AP Carrier)
	MinIMU-9 v2 Gyro, Accelerometer, and Compass (L3GD20 and LSM303DLHC Carrier)
	AltIMU-10 Gyro, Accelerometer, Compass, and Altimeter (L3GD20, LSM303DLHC, and LPS331AP Carrier)
	MinIMU-9 v3 Gyro, Accelerometer, and Compass (L3GD20H and LSM303D Carrier)

We are expanding our selection of products from Adafruit, and the latest addition is the Adafruit Pi Case, a stylish protective enclosure for the Raspberry Pi. And to celebrate, we are dropping the price of our Raspberry Pis!

Related products

	Adafruit Pi Case - Enclosure for Raspberry Pi Model A or B
	Raspberry Pi Model B, Revision 2.0

Looking for a power supply for your Raspberry Pis, Arduinos, Wixels, or Maestro servo controllers? Look no further!

This UL-certified AC-to-DC converter gives you an easy way to deliver up to 1 A to your USB-powered device from a US-style AC electrical socket. It has been specifically designed to supply 5.25 V instead of 5 V to help ensure that the device it is powering receives close to 5 V even when the current draw is high. This converter is safe for use with USB-compliant devices.

This adapter does not include a USB cable, but it features a USB “A” port that you can plug a standard USB cable into, which makes it great for transitioning your project from USB to wall power.

For more information, see the 5V wall power adapter product page.

Related products

Wall Power Adapter: 5.25VDC, 1A, USB Port

Frédéric Jelmoni built a neat robot with a Raspberry Pi and a Zumo Chassis Kit. The Raspberry Zumo robot can be controlled over WiFi using telnet. The server on the Raspberry Pi is written in Python and uses the RPIO library to send signals to an SN754410 motor driver that drives the two 100:1 Micro Metal Gearmotors HP in the Zumo chassis. The server also controls an RGB LED and a buzzer. A stripped-down Logitech webcam attached to the front of the robot provides video that is streamed over the web using mjpg-streamer.

For more details, see the Raspberry Zumo page, which is written in French. Also, see our post from last October about a similar robot, the Pibot-B.

Related products

	Raspberry Pi Model B, Revision 2.0
	SN754410 Motor Driver IC
	Zumo Chassis Kit (No Motors)
	100:1 Micro Metal Gearmotor HP 6V

We saw this robotic ping-pong ball collector by Will Jessop on the Raspberry Pi blog a few days ago. The robot uses the Pololu 30T Track Set, a Raspberry Pi, and a lot of custom electrical and 3d-printed mechanical parts.

Apparently, Will plans to put his robot into service at the office of his employer, 37signals. This is exciting for us at Pololu because 37signals is the originator and a major sponsor of the Ruby on Rails web framework, on which our website is built. And although we did not attend this year’s RubyConf, we are proud that some of our parts, as shown in the video above, made an appearance.

You can find detailed build information in Will’s ping-pong robot blog posts.

Related products

	Raspberry Pi Model B, Revision 2.0
	Pololu 30T Track Set

We are now carrying the Raspberry Pi Model B, Revision 2.0!

In case you haven’t heard of the Raspberry Pi, it is a popular credit card-sized computer that can run Linux. It was designed by the Raspberry Pi Foundation in order to provide an affordable platform for experimentation and education in computer programming. The Raspberry Pi can be used for many of the things that a normal desktop PC does, including word-processing, spreadsheets, high-definition video, games, and programming. With its 0.1″-spaced GPIO header and small size, the Raspberry Pi also works as a programmable controller in a wide variety of robotics and electronics applications. We have seen a lot of our customers do neat things with the Raspberry Pi, and we have featured several of those projects on this blog.

Related past posts featuring the Raspberry Pi:

• Digital Capabilities: a digital garden
• Controlling a Maestro in C using a Raspberry Pi
• Dagu Rover 5 controlled by a Raspberry Pi
• PiBBOT
• Raspberry Pi Telepresence Rover
• Raspberry Pi-based State Poster Project
• Raspberry Pi – Real Time Control via Android HTML5
• Pi-Trak
• Using a Maestro to control a quadcopter
• PiBot-B: mobile robot with a Raspberry Pi
• Wireless Servo Widget

For more information on the Raspberry Pi, see the product page.

Pololu forum user Martan recently released a project called Wireless Servo Widget. The project website says:

Wireless Servo Widgets allow you to control up to 64 slaves, with each slave controlling up to six R/C type servos. In addition, each slave can return 3 analog input values to your Raspberry Pi. Slaves have a range of about 50 feet from the master. Use them for home automation, robotics, model train controls, or whatever you want!

The Wireless Servo Widget is based on our Wixel Programmable USB Wireless Module. Martan wrote apps for the Wixel that use the packet addressing feature of the CC2511F32 chip to implement a round-robin protocol. He also made a Slave Widget Breakout Board which makes it easy to plug servos into the slave Wixels. All of this and more can be found on the Wireless Servo Widget website.

Related products

	Wixel Programmable USB Wireless Module
	Raspberry Pi Model B+