Guest Blog by William P. Risk and Michael V. Debole with Contributions from Rodrigo Alvarez-Icaza and Filipp Akopyan.
A few months ago, we unveiled the NeuroSynaptic Evaluation (NS1e) board, which contained a single TrueNorth chip, along with circuitry for interfacing the chip to sensors and real-world data. These boards were used in our August 2015 “Boot Camp” event, in which participants learned how to program the chip to implement cognitive systems [Brain-Inspired Computing Boot Camp Begins]. During BootCamp, each NS1e board was housed in its own plastic case, and for convenience, we built a rack to hold the 48 boards used during that event. Although the rack nicely organized and displayed the boards, a bulky assembly of power strips, ethernet switches, and servers were also required for their use.
Recently, a government client requested that we build a system of 16 NS1e boards, with power unit, ethernet switch, and Linux server all housed in a compact, self-contained unit, where each of the NS1e boards can be seamlessly integrated, but mounted in such a way that any individual board could be swapped in or out easily. This requirement led us to explore designs in which individual NS1e boards are mounted on cards that could be inserted vertically into a card rack (Figure 1) and all elements were mounted in a small desktop rack unit (shown below).
Figure 1. NS1e Card Rack
We initially considered two similar designs, both using a 6U high desktop rack with components stacked as follows: (bottom) 1U – power-strip / network switch, 3U – NS1e card rack, 1U NS1e card power, 1U server. We ultimately chose the design with wiring in the back as it provided a cleaner looking front panel.
Figure 2. Final Design Concept
The next step was determining how to make the concept become a reality. For the most part, this was a straightforward process since we were able to use many off-the-shelf components (server, network switch, power strip, etc..). However, powering 16 NS1e boards required a bit of engineering to reduce the space required. As standalone boards, each is typically powered by an AC-DC adapter which simply plugs into a standard outlet, but including 16 bulky “wall warts” in a 1U form factor was impractical. In addition, we wanted to provide the capability to remotely monitor the current consumption of each individual board and to control its power state. To solve this problem we turned to a USB-style power distribution module developed by Cambrionix. While normally intended to charge and sync cell phones and tablets, it’s port capacity (16 USB ports) and current limits were suitable for our purposes. However, with typical USB connectors plugged into the Cambrionix board, the height required was close to 2U (3.5″), greater than the 1U we had allocated for the power distribution unit in the initial design. Fortunately, the card rack holding the NS1e boards did not occupy the full depth of the rack and we had just enough room to design a step-down enclosure using 1U of space above the NS1e drawer and dropping down to 2U in the back (See below). Finally, to give some visual appeal, we united the 16 individual NS1e boards by spreading a graphic (our award-winning visualization of the network diagram of the monkey brain) across their front panels and added some accentuating LED strip lighting on both sides of the drawer and below the chassis.
Building the system, once all the planning was complete, was relatively straightforward:
Figure 3. Initial Skeleton
Figure 4. Early Prototype Front and Back
Figure 5. Functional Prototype (Alpha)
Figure 6. Functional Prototype (Beta)
Figure 7. Custom Power Enclosure
Figure 8. Final Lab Photo
Figure 9. Final Photo
Then crated and shipped!
Figure 10. Preparing to ship system to clients
The end result is a system that provides 16 million neurons and 4 billion synapses in a package about the size of a carry-on suitcase!