Seth Newburg of NK Labs (an engineering company) talks about the hardware for module developers.
Spiral 1 dev board
“First, I’d like to review the Spiral 1 developer hardware that we presented at the first developers conference back in April 2014.”
“These are the developer boards that we presented at first developers conference back in April 2014. In the middle of the image there is the endo switch board. This board presents all electronics of the Endoskeleton with the UniPro switch implemented in FPGA (field-programmable gate array). On the right side of the image is the AP dev board. This has the application processor, as well as an FPGA bridge on the UniPro network. On the left of the picture you see a general purpose end-point dev board that has GP (general purpose) bridge and connectors for all interface protocols that you want to develop for. This is a dev board that you would use to create other modules. Three boards are connected together with SMA cables which route the UniPro signals between the boards.”
Spiral 2 dev board
“Today we are presenting Spiral 2 developer hardware. This image of the Spiral 2 dev board is called “Big dev board”. It’s an entire Ara phone on a single board. It has the switch, as well as all electronics of the Endo, and the UniPro signals are routed via single PCB (printed circuit board). This is the hardware that the Ara platform development team is using to create the Spiral 2 prototype phone. These are the same tools that we are making available to developers.”
Spiral 1 dev board vs Spiral 2 dev board
“There are some differences between the Spiral 1 development hardware and Spiral 2 development hardware. These differences are in the silicon technology, in the interconnect between the devices and in the packaging of the silicon devices.
On the upper right of the slide the Spiral 1 bridges are implemented FPGA (field-programmable gate array). This is a general purpose bridge FPGA and its package is 10mm x 10mm.
On the lower right of the slide we have the Spiral 2 general purpose bridge ASIC. This is ASIC (application-specific integrated circuit), it has all functions of the general purpose bridge and about a quarter of the area (5mm x 5mm package).
So in Spiral 1 we’ve developed the UniPro bridges on FPGA, Spiral 2 is on custom silicon ASICs.
The physical layer connecting the electrical signalling between the UniPro switch and bridges in Spiral 1 is LVDS (Low-voltage differential signaling) running at 800 Mbps. In Spiral 2 the physical layer is M-PHY, and we have two lanes of High-Speed Gear 3 (HS-G3) M-PHY, connecting each port of the switch to each module. And this gives us an aggregate rate of 11.6 Gbps in each direction.
The trace length on the PCB actually limits the speed of the M-PHY to High-Speed Gear 1 (HS-G1). So we have 2.5 Gbps available for each module.”
In Spiral 1 there are 6 UniPro ports on the switch, in Spiral 2 the switch has 14 UniPro ports.
In Spiral 1 dev boards there are 8 SMA cables, for each UniPro link between the boards. And in Spiral 2 on the big dev board with the on-board PCB with the UniPro routed on traces on the PCB, there are zero cables for the UniPro connections.
Block diagram of the Big Development Board
“This is a block diagram of the big dev board. It has the ASIC switch, 14-port switch, and the modules. There are the bridges, the high-speed bridges, the general-purpose bridges as well as the interface blocks for form-factor modules. Each bridge that is mounted on the PCB is connected to connectors for various peripheral interfaces, including SDIO (Secure Digital Input Output) and I2C (Inter-IC). On the left side of the image you can see the application processor boards that come with the big dev board. We have two different application processor boards that can be connected. One board is based on Marvell PXA 1928 processor, another board is based on NVIDIA TK1 processor.”
Developers may request Big Development Board here