Robotic controler for Raspberry-Pi

Arduino compatible robotic controler for Raspberry-Pi

Simply put, this fully assembled card is an Arduino compatible micro-controller with a driver for continuous motors (2 channels of 1.8A), voltage regulator, user button, buzzer, BUT especially a communication channel with your Raspberry-Pi (via I2C). Able to power your Raspberry-Pi.  
As this is an Arduino compatible, you can also connect your own sensors to the micro-controller that will exchange its results with your Raspberry-Pi.
Ideal for robotic projects, it's like RPi-ShieldBridge but really better :-) 

It's the product Pololu "A-Star 32U4 LV Robot Controller with Raspberry Pi Bridge" all ready to be used with the Zumo platform.

That's not all!

This programmable module, combined with a Raspberry-Pi, will serve as a control center for a small Robot or electronic project. It is equipped with an Atmel ATmega32U4 micro-controller preloaded with an Arduino compatible boot-loader. So you can program it as an Arduino from the Arduino IDE environment.  
The card includes a motor driver capable of delivering up to 1.8 A per channel, thus making it possible to drive two continuous motors (brushed DC motors). The card is also equipped with a powerful voltage regulator and logic level matching circuit (Level Shifter) to facilitate communication with your Raspberry-Pi (in 3.3V). The voltage regulator can also power your Pi from this HAT.   

This product is delivered fully assembled, at MC Hobby, we opted for this model to allow our Makers to start very quickly without having to take out the welding iron.  

The A-Star 32U4 LC Robot Controller (A-Star 32U4 LV Robot Controller) with connection/bridge for Raspberry-Pi proves to be a product well suited to robotic applications.   
A real tour de force, this card is designed to work:

• As an auxiliary controller (eyes, hands, legs) mounted on a Raspberry-Pi (the brain). It then becomes a HAT.
• As an Arduino compatible solution totally autonomous to realize a small Robot. Yes it is also an Arduino compatible on its own. 

This A-Star (A* for the intimates) is based on the Atmel ATmega32U4 AVR micro-controller which integrates USB support (inside the micro-controller) and already has an Arduino compatible boot-loader. 
It is supplemented by the following peripherals:

• A driver for two continuous motors (1.8A max per motor).
• Push buttons,
• LEDs,
• A Piezzo Buzzer.
• A powerful voltage regulator (voltage between 2.7V and 11V).

If you want to use it as a HAT for your Raspberry, this product meets HAT specifications and can therefore be placed on the GPIO 40 pins of your Raspberry-Pi 2, Model B+ or Model A+. The Level Shifter (Logic level adaptation) make it easy to establish an I2C communication channel and interface other signals between the two controllers. The A-Star will automatically supply the 5V power voltage to the Raspberry-Pi (via the GPIO connector). In this configuration, the Raspberry-Pi can manage the robot's high-level functions while delegating low-level tasks (motor control, sensors acquisition, servo control and time-based peripherals) to the A-Star micro-controller.   

Pololu offers a user guide (English) documenting the basics needed to get started quickly with A-Star, the guide also includes detailed information for advanced users.

Note that you will need a USB A to micro-B cable to program the Arduino compatible micro-controller.

Technical details

This version of the "A-Star 32U4 LV Robot Controller with Raspberry-Pi Bridge" is assembled and equipped with terminal block connectors and components for use as an expansion card for your Raspberry-Pi (see product images). A 2x20-pin connector (2.54mm, female) is pre-installed on the card and will be used to connect the HAT to your Raspberry-Pi. The power is supplied via a Standard Jack connector (positive center). A terminal block with 6 contact points makes it possible to connect the two motors + the power supply (if you don't use the Jack connector).    

The buzzer is also installed (you can disable it with a jumper). You can also measure the battery level on pin A1 (also deactivated with a jumper).

This version is delivered with 4 standoffs M2.5 spacers (11mm long), screws and nuts to attach the HAT very easily on your Raspberry-Pi.

• Dimensions: 65 mm × 56 mm
• ATmega32U4 programmable with 32 KB flash, 2.5 KB SRAM, 1 KB EEPROM and native USB support (full-speed). A precision crystal oscillator of 16 MHz.
• Preloaded with an Arduino compatible boot-loader (no need for an external programmer)
• All 26 GPIO pins of the ATmega32U4 are available in breakouts (including PB0, PD5 and PE2); 7 of them can be used as hardware PWM output and 12 of them can be used as analog inputs (some of these I/O are used by the hardware available on the card)
• Connection point with an impaction of 2.54mm (really handy) for: power, ground and signals.
• Motor driver DRV8838. For two motors, in both directions, max 1.8A per motor.
• A Buzzer to make sounds (or music). Convenient to alert the user.
• 3 LEDs controllable by the user.
• 3 User push buttons.
• 1 Reset button 
• Level shifters (Logic level adapter) for 5V logic interface on the 3.3V logic of the Raspberry-Pi.
• Power features:
  
  • Can be powered via USB
  • Can be powered via an external source 2.7 V to 11 V.
    Multiple access points to connect an external power source.
  • 5V Voltage regulator (switching) for efficient operation
  • Power switch (for external power input)
  • Reverse bias protection (on the external power input).
  • Power source selection circuit (automatic selection of the uninterruptible source). Also provides over-current (overload) protection and a status to detect the selected power source. 
  • Provides 5V power supply to the Raspberry-Pi
• A 6-pin ISP connector to use an external programmer
• A detailed and affordable user guide (Pololu, English)

Arduino compatibility

Like other Pololu A-Star 32U4 micro-controllers (see full Pololu range), this A-Star 32U4 Robot Controller is preloaded with an Arduino compatible boot-loader (which uses 4 KB of flash memory, leaving 28 KB available for your user program). Pololu offers an add-on to allow the card to be easily programmed from the Arduino IDE environment - AND - an Arduino library to easily take control of the hardware available on the card. 

The micro-controller on the A-Star 32U4 Robot Controller card (this product) is the same as the one used for the Arduino Leonardo and Arduino Micro. It also works at the same frequency, so most of the sample codes for these cards should also work on the A-Star.

The A-Star 32U4 Robot Controller (this product) is part of a larger family, the A-Star 32U4 family (some of which are already available at MCHobby) whose members are all based on the same ATmega32U4 micro-controller. This family has a native USB support and an Arduino compatible boot-loader. 

Contain

This product: fully assembled and tested "A-Star 32U4 Robot Controller LV with Raspberry Pi Bridge" card and spacers.  

The Raspberry-Pi, motors, battery pack and other accessories - used for illustration - are not included!