April 22, 2013

$45 BeagleBone Black Keeps Eyes on the Pi's

Much of the news in the BeagleBone Black open source ARM board release was teased by BeagleBone.org over a month ago. We already knew there would be a faster processor, a doubling of RAM to 512MB, the addition of onboard flash, and best of all, a micro-HDMI port. Yet today's unveiling of the second generation of the Linux- and Android-based hacker board still held plenty of drama, thanks to a single detail: $45. The halving of the price of the previously $89 single board computer (SBC) makes the BeagleBone cheaper than most Arduino boards and just above the $25-$35 Raspberry Pi.

beaglebone blackThe $45 price is a testament both to the growing competition from the Pi, as well as the large volume of units BeagleBoard.org and its manufacturing partner CircuitCo have pushed out since late 2011 when the BeagleBone arrived as a smaller, cheaper alternative to the BeagleBoard. According to BeagleBoard.org co-founder Jason Kridner, the price cut derived entirely from design decisions and economies of scale. There was no subsidization from any source, including Kridner's employer Texas Instruments (TI). The chip manufacturer has helped promote the BeagleBoard and BeagleBone, enjoying increased awareness and sales of its ARM-Cortex A8 Sitara processors in return, but has taken a largely hands-off approach.

"The $45 price is mostly due to volume," said Kridner, who is also Software Architecture Manager for Applications Processors at TI. "We've already received large orders for the BeagleBone Black. The distributors came to us."

BeagleBone Hardware Updates

Instead of moving to a multicore Cortex-A9 architecture, as have open boards like the Origen, PandaBoard, and Snowball, as well as recent commercial ARM modules and SBCs, BeagleBoard.org cut costs by sticking with Cortex-A8. The board has advanced from a 720MHz Sitara AM3358 chip to an almost identical new 1GHz Sitara AM3359. Performance is further enhanced by doubling memory to 512MB of faster DDR3 RAM, which Kridner noted is now cheaper than DDR2, enabling further savings.

Moving to Cortex-A9 is costly for several reasons, said Kridner. "When you look at these multicore beasts, you not only pay more for the processor, but for the power management, which may require adding a microcontroller," he said. "Multicore also makes development trickier."

BeagleBoard.org's pricing decisions reflect the huge popularity of the low-cost, ARM11-based Raspberry Pi, which along with the BeagleBone, has largely eclipsed other open source boards. Both projects are not only competing for embedded Linux developers, but also for Arduino hackers looking to move up to a more robust Linux environment, as well as other "maker" gadgeteers building everything from robots to 3D printers.

While the more publicized Pi has had the greater momentum and geek chic appeal, Kridner makes a compelling case for the BeagleBone Black, starting with its processor.

"The AM335x sells for $5 in quantity, and has some key advantages for the maker market," said Kridner. "It offers a unique peripheral mix of serial ports, CAN bus, parallel buses, A/D converters, and analog controls. It stands out with features like pulse width modulation, which helps to do things like controlling robot motors. We're addressing the needs of the maker crowd and Kickstarter projects, all the way up to professional industrial developers."

Plug and Play

The rich I/O mix remains pretty much the same on the BeagleBone Black, including a 10/100 Ethernet port, USB host and client ports, and expansion headers for the BeagleBone's "cape" add-ons. The device, which shares the original's 3.4 x 2.1 footprint, is compatible with over 30 BeagleBone capes available from CircuitCo, including wireless extensions, touchscreens, motors, and I/O breakouts. In addition to the expansion I/O, which includes 65 digital interfaces, both versions of the BeagleBone can also tap the Sitara's programmable real-time unit (PRU), which combines dual 32-bit RISC microcontrollers to enable reconfiguring and customizing I/O.

The BeagleBone Black has also shed some interfaces. "We removed some less used features like USB-to-serial and USB-to-JTAG, which saves on power and cost, but there's a serial-header workaround," said Kridner.

The SBC's only new interface is a big one: the much-requested micro-HDMI port. Instead of being limited to a touchscreen "cape" add-on or otherwise hacking the 24-bit LCD controller, developers can just plug in. "We're now totally plug and play on monitors and TVs," said Kridner.

Almost as welcome is the 2GB of onboard eMMC flash. Preloaded with Angstrom Linux, the flash frees the microSD slot for storage. "You can still boot off the microSD card image to run Ubuntu or something," noted Kridner.

The BeagleBone Black retains the 3.4 x 2.1-inch profile of the original. Surprisingly, power consumption on the Black appears to be slightly lower, or 210-460 mA@5V compared to 300-500mA@5V. This translates to about 2.3 Watts for peak kernel loading (460 mA@5V).

BeagleBone Adds Yocto Compatibility

The ARM11-based Raspberry Pi is still cheaper, but other advantages, such as the HDMI port, have largely been eclipsed by the BeagleBone Black. In addition to its greater I/O, the BeagleBone Black is faster, and supports Android in addition to Linux distros like the pre-installed Angstrom, plus Fedora, Ubuntu, and Arch. "There is tremendous interest in doing Android development on the BeagleBone," said Kridner. The board also supports OSes like FreeBSD, QNX, and Windows Embedded.

The updated Angstrom release is newly compatible with the Linux Foundation's Yocto Project code. The BeagleBone distribution also includes Linaro toolchain, a C compiler, Python, Qt, OpenCD, over 200 libraries, various webservers, and the Cloud9 IDE.

The BeagleBone is more open source than the Raspberry Pi, claimed Kridner. "With the Pi, you cannot do anything you want with your design," he said. "You are not completely free to customize it or alter it."

The simpler Raspberry Pi may still have the advantage in ease of use, which is important for a platform aimed primarily at public schools. BeagleBoard.org is pushing the BeagleBone as an educational platform, as well. With its "Arduino-like" Bonescript Linux/Javascript language, combined with the device's faster processor and richer I/O, the BeagleBone Black is better for teaching embedded development than the Pi, argued Kridner.

"Sometimes students need more of a visceral interaction to get engaged," said Kridner. "You really need all this I/O to do things like robotics, which is one of the best things that we're doing in early education." Among other educational initiatives, Kridner noted BeagleBoard.org's participation in Google Summer of Code 2013, as well as the coming availability of several "college-level and maker-level books" on the BeagleBone.

Kridner sees a particularly compelling role for the BeagleBone in 3D printers. "Without adding an Arduino, people are already building 3D printers with BeagleBones, doing proportional control for the heating element," said Kridner, perhaps referring to recent "Cape Contest" winner Replicape. "Linux is definitely moving into 3D printers," he added.

With the BeagleBone Black's lower price, Kridner expects developers will be more likely to compare the board with the Pi -- and like what they see. "At $45, you can put these boards in your projects and forget about them," said Kridner. "We're the ones that changed the market, and we continue to engage with the community. I don't think there's really a whole lot of room for too many other open source boards."

We shall see. Meanwhile, the BeagleBone Black ison sale in limited quantities, with volume shipments expected by May.