Get a FREE copy of Circuit Cellar magazine’s April issue with your order while supplies last. To get your free issue, enter the coupon code CIRCUIT0414 into your shopping cart. The magazine will add 6 ounces to the package weight when calculating your shipping options.

For other issues and more information, see our Free Circuit Cellar Magazine Offers page. All issues are now available for shipping worldwide!

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Free Circuit Cellar magazine April 2014

Get a FREE copy of Elektor magazine’s April issue with your order while supplies last. To get your free issue, enter the coupon code ELEKTOR0414 into your shopping cart. The magazine will add 7 ounces to the package weight when calculating your shipping options.

For other issues and more information, see our Free Elektor Magazine Offers page. All issues are now available for shipping worldwide!

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Free Elektor magazine April 2014

Today we released a general-purpose AVR microcontroller breakout board, the A-Star 32U4 Micro. But before I get to the A-Star (A* for short), I would like to mention some of our history with AVR boards.

Some of our history with AVR boards

Original Orangutan Robot Controller (back view) from 2004.

It has been almost ten years since we introduced our Orangutan Robot Controller, which featured an AVR microcontroller, dual motor drivers, and user-friendly features like a display and buzzer. Over the years we expanded the line, making larger, more complicated Orangutans like the Orangutan SVP as well as the miniature Baby Orangutan.

I have used the Baby Orangutan in many of my own projects, because I like its simplicity and small size. Ironically, the built-in motor driver gets in the way when I want to use a newer motor driver such as the DRV8835 in a project, since valuable PWM pins are unavailable. So I have built my more recent robots using minimal microcontroller breakout boards without motor drivers, such as Arduinos and the Wixel. (I posted about my latest such project last week.)

Our focus has been on boards that include motor drivers, and we have not had a really simple microcontroller board for people who don’t want the motor driver. Even though there are far more powerful controllers available, 8-bit AVR microcontrollers continue to be popular in the community, and the basic AVR breakout board is something we have wanted to make for a long time.

Original ATmega168-based Baby Orangutan robot controller from 2005 (left) next to A-Star 32U4 Micro boards.

Introducing the A-Star 32U4 Micro

That is why I am excited today to announce the A-Star 32U4 Micro, a Pololu breakout board for Atmel’s ATmega32U4 AVR microcontroller:

A-Star 32U4 Micro pinout diagram.

Compared to the popular ATmega328P microcontroller that we used on several Orangutan models, the ATmega32U4 is a newer processor with features like more analog inputs, more PWM outputs, and, most importantly, USB support. The USB connection, which we have broken out to a Micro-B connector, makes programming easy and enables interesting projects involving connections to a PC.

Also, since the ATmega32U4 is used on the Arduino Leonardo, Arduino Micro, and many other breakout boards, there is a large community with experience using the microcontroller. To support this community, we are shipping the A* with an Arduino-compatible bootloader and have followed Arduino conventions including pin numbering and LED connections.

Since we wanted to make a minimal breakout board, we decided to make it as small as we could, hoping that it would be small and cheap enough to go into (and stay in) almost any project. The result is that the A-Star 32U4 Micro is, as far as we know, the smallest ATmega32U4 breakout board available. It is even smaller than some AVR boards with less powerful microcontrollers that implement USB support in software and have only a few general-purpose I/O lines available.

The Pololu A-Star 32U4 Micro is about half the size of an Arduino Micro.

Now that we have reached a reasonable extreme on the minimal end, we intend to expand back toward more integrated features, eventually replacing our older Orangutan robot controllers with versions offering more modern power handling and perhaps other features like inertial measurement sensors. What would you like to see in an integrated robotics or automation controller? Did we leave out too much on the A-Star 32U4 Micro? Please let us know in the comment section.

For more information, see the A-Star 32U4 Micro product page.

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	A-Star 32U4 Micro
	Arduino Micro
	Baby Orangutan B-328 Robot Controller
	Arduino Leonardo

These new 130-size motors are great for applications that require a lot of power in a small package. They are a generic alternative the Solarbotics RM2 motors, which have the same form factor and nearly identical performance. With a free-run speed of 17,000 RPM at 3 V, they are great for upgrading projects driven by lower-power 130-size motors. For example, see this post from last year about upgrading flywheel NERF guns. This motor is also compatible with our larger Pololu plastic gearmotors (228:1 offset, 120:1 offset, 200:1 90-degree, and 120:1 90-degree) and Solarbotics plastic gearmotors (GM2, GM3, GM8, and GM9).

For more information see the Brushed DC Motor: 130-Size, 3V, 17kRPM, 3.6A Stall product page.

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	Brushed DC Motor: 130-Size, 3V, 20kRPM, 4A Stall
	Solarbotics RM2 (high-power motor for GM2/3/8/9)
	228:1 Plastic Gearmotor, Offset Output
	120:1 Plastic Gearmotor, Offset Output
	200:1 Plastic Gearmotor, 90° Output
	120:1 Plastic Gearmotor, 90° Output
	Solarbotics GM2 224:1 Gear Motor Offset Output
	Solarbotics GM3 224:1 Gear Motor 90 deg. Output
	Solarbotics GM8 143:1 Gear Motor Offset Output
	Solarbotics GM9 143:1 Gear Motor 90 deg. Output

We’ve released an updated version of our dual VNH5019 motor driver shield for Arduino. The VNH5019 is a great solution for driving high-power motors, with each chip able to supply up to 12 A continuously at 5.5 V to 24 V. However, the original version of our dual VNH5019 shield was designed before the Arduino Uno R3 was released, so it lacked pass-throughs for the four new pins (SCL, SDA, IOREF, and an unused pin) introduced by the R3 and present on all newer Arduinos. This makes it harder to stack other shields with it, especially ones that make use of the new I²C pin location. The latest board revision adds these pass-throughs to make the shield fully compatible with the Uno R3 pinout.

For more information, see the dual VNH5019 motor driver shield product page and user’s guide.

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	Pololu Dual VNH5019 Motor Driver Shield for Arduino
	Pololu Dual VNH5019 Motor Driver Shield for Arduino (ash02a)

We are happy to introduce new v3 versions of our MinIMU-9 and AltIMU-10 inertial measurement units (IMUs). These sensor modules are the same compact sizes as their predecessors and have same pin-out, but they are based on ST’s newer and better L3GD20H 3-axis gyro and LSM303D 3-axis accelerometer/magnetometer. The nine independent rotation, acceleration, and magnetic measurements from these sensors provide all of the information required make an attitude and heading reference system (AHRS). In addition to this, the AltIMU-10 v3 incorporates an LPS331AP digital barometer that can be used to measure pressure and altitude.

The new revisions offer a wider magnetic sensing range and a more accurate and stable gyro, all with lower power consumption, and they include an extra pin for changing the I²C slave addresses so that two boards can be used on the same I²C bus. They should generally be usable as drop-in replacements for our previous MinIMU-9 v2 and AltIMU-10 modules—which we have put on clearance—though changes to register locations might require updates to software that is not based on our Arduino libraries.

We also have individual carrier boards available for the L3GD20H gyro, LSM303D accelerometer/magnetometer, and LPS331AP barometer if your application doesn’t require quite so much data or if you want to build your own AHRS unit.

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)
	LPS331AP Pressure/Altitude Sensor Carrier with Voltage Regulator
	L3GD20H 3-Axis Gyro Carrier with Voltage Regulator
	LSM303D 3D Compass and Accelerometer Carrier with Voltage Regulator

Get a FREE copy of Elektor magazine’s March issue with your order while supplies last. To get your free issue, enter the coupon code ELEKTOR0314 into your shopping cart. The magazine will add 6 ounces to the package weight when calculating your shipping options.

For other issues and more information, see our Free Elektor Magazine Offers page. All issues are now available for shipping worldwide!

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Free Elektor magazine March 2014

We have new gyros fresh out of the oven. No, I’m not talking about a Greek dish. I’m talking about our new L3GD20H 3-axis gyro carrier.

One of the most important measures of a rate gyroscope’s performance is the amount of noise in its output, which is indicated by its noise density specification. Too much noise means that the gyro will be prone to spurious indications of rotation, and if the gyro readings are integrated to track orientation, noise will cause the calculation to drift over time.

Although sensor fusion can help compensate for this drift by combining the gyro data with an absolute reference (like magnetometer data), using a lower-noise gyro is likely to be a more effective way to improve orientation tracking accuracy. In that respect, one of the biggest improvements of the L3GD20H over its predecessor is that it has a 60% lower rate noise density (0.011 dps/√Hz compared to 0.03 dps/√Hz on the L3GD20).

In addition to accuracy and stability improvements, the L3GD20H offers other advantages. Its power consumption is lower and its start-up time is much shorter. A wider range of user-selectable output data rates is available, including lower frequencies that are appropriate for human gesture detection, and a data enable (DEN) pin allows readings to be synchronized with external triggers. The L3GD20H makes all of these features available in a smaller package than previous gyros, which has allowed us to design a correspondingly smaller carrier board for it while still keeping it breadboard-friendly. For more information, see the L3GD20H carrier product page.

If you don’t need the latest and greatest, the L3GD20 is still a nice sensor, and it’s a good time to grab one now that we’ve lowered the price of our L3GD20 carrier to only $14.95 until stock runs out.

Related products

	L3GD20 3-Axis Gyro Carrier with Voltage Regulator
	L3GD20H 3-Axis Gyro Carrier with Voltage Regulator

We are now carrying the latest version of SparkFun’s Inventor’s Kit (V3.1), which adds a mini screwdriver and replaces the translucent red breadboard from version 3 with an opaque white one that is easier to read. Version 3.1 includes everything else that was part of the previous version, such as the Arduino-compatible RedBoard and all of the additional components needed to build the 15 basic electronic circuits detailed in the guide.

For more information see the SparkFun Inventor’s Kit – V3.1 (with Arduino-Compatible RedBoard) product page.

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SparkFun Inventor's Kit - V3.1 (with Arduino-Compatible RedBoard)

Do you want to build your own weather monitoring station? This weather shield from SparkFun might be what you are looking for. In the form of an Arduino shield, this easy-to-use weather board can measure relative humidity, temperature, barometric pressure, and luminosity.

For more information, see the SparkFun Weather Shield for Arduino product page.

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SparkFun Weather Shield for Arduino