Designed for Raspberry Pi robotics projects, does the expandable UltraBorg deliver on its promises or let us down?
Designed primarily for the Raspberry Pi yet compatible with any microcomputer or microcontroller that can speak inter-integrated circuit (I2C) – including the popular Arduino and compatible – PiBorg’s UltraBorg is built with one task in mind: robotics.
The majority of hobbyist-level robotic projects use two major components: servos, controlled via pulse width modulation (PWM) to move the robotic parts, and ultrasonic sensors, which send out a pulse of inaudible sound and listen back for the echo to measure distance to solid objects. Combined, that’s enough to build everything from a simple two-wheel robot to a more complex roboticarm, although computervision, aided by devices like the Raspberry Pi Camera Module, can help with accurate positioning for the latter.
While it can’t help you with the camera side of things, the UltraBorg is positioned as the ultimate one-stop device for budding roboticists. The board is split into two four channel groups: the first group provides input support for four ultrasonic sensor modules; the second group provides output support for four servos or other PWM controlled motors. All told, that’s enough for a reasonably proficient robot, but if you need more it’s possible to daisy-chain multiple UltraBorgs together to gain additional input and output channels, a handy feature tempered only by the £15.99 asking price per board.
The UltraBorg includes an on-board processor, a PIC, which provides for real-time sensing and control while taking the pressure off thePi–more of an issue for the single-core ModelB+ and ModelA+ than the quad-core Raspberry Pi 2 – while a Toshiba PWM controller provides 16-bit precision, an improvement on the 8- or 12-bit of its rivals. You don’t need to know how to program a PIC to use the device as the chip arrives pre-programmed and sample code is provided for user-level interaction.
Installation of the UltraBorg is simple, taking up the first six pins of the GPIO header, although the use of multiple ultrasonic sensors or any number of servos will require a separate 5V power supply, which is not provided with the board. This connects to a screw terminal and can also supply power to the Pi itself, along with any additional UltraBorg boards, to make wiring as easy as possible to conduct.
A particularly handy feature of the UltraBorg is the electrically erasable, programmable read-only memory (EEPROM) located within the PIC process, which is used to store start-up and limit values for the PWM outputs. Using this you can set a custom zero-point for your particular servos, while also limiting their minimum and maximum rotation points. When power is cut and reapplied, the servos will automatically return to the zero you have set. For protecting your build against damage from improper values or bad defaults, it’s a must-have.
Although the UltraBorg isn’t a Hardware Attached on Top (HAT) standard device, it has been designed with piggyback mounting in mind. Screw holes on the board itself are positioned to enable it to be attached above or below any model of Raspberry Pi bar the Compute Module or the very original Model B. These same holes can also be used to mount the device elsewhere if you are sacrificing footprint for thinness or using it with a different microcomputer or microcontroller, a job made easier thanks to the small size and weight of the board.
PiBorg hasn’t just launched the device blindly either. The Pi-centric company has designed a range of accessories, including a BattBorg battery power supply, a 90-degree mounting bracket for the ultrasonic sensors and bundles which include quality servo motors, sensors, and all the connecting cables. Gareth Halfacree
Pros
High-precision PWM control combined with multi-channel ultrasonic sensor inputs make getting started with robotics as simple as possible for all.
Cons
Those with more complex projects will find that daisy-chaining multiple UltraBorgs can get expensive compared to lower precision 16-channel alternatives.
Summary
The UltraBorg is a marvellous device, with a compact size that belies its capabilities. The idea of combining both input and output onto one board means that it’s a literal one-stop-shop for simple robotics projects, and the daisy-chaining support makes extending it simple. However, sadly it is quite expensive compared to its 16-channel competition that’s available.
Type Add-On Board (Non-HAT)
Processor PIC16F1824-I/SL
Driver Toshiba 16-bit PWM IC TC62D723FNG
Outputs 4x 5V PWM (Servo-compatible)
Inputs 4x 5V Ultrasonic Sensor
Power Supply 5V required for servo use, not supplied
Price From £15.99 ($25 approx)
Available from piborg.org