Design Resources: USB 3.1 and Type-C

By: Chris A. Ciufo, Editor, Embedded Systems Engineering

An up-to-date quick reference list for engineers designing with Type-C.

USB 3.1 and its new Type-C connector are likely in your design near-future. USB 3.1 and the Type-C connector run at up to 10 Gbps, and Type-C is the USB-IF’s “does everything” connector that can be inserted either way (and never is upside down). The Type-C connector also delivers USB 3.1 speeds plus other gigabit protocols simultaneously, including DisplayPort, HDMI, Thunderbolt, PCI Express and more.

Also new or updated are the Battery Charging (BC) and Power Delivery (PD) specifications that provide up to 100W of charge capability in an effort to eliminate the need for a drawer full of incompatible wall warts.

If you’ve got USB 3.1 “SuperSpeed+” or the Type-C connector in your future, here’s a recent list of design resources, articles and websites that can help get you up to speed.

Start Here: The USB Interface Forum governs all of these specs, with lots of input from industry partners like Intel and Microsoft. USB 3.1 (it’s actually Gen 2), Type-C, and PD information is available via the USB-IF and it’s the best place to go for the actual details (note the hotlinks). Even if you don’t read them now, you know you’re going to need to read them eventually.

“Developer Days” The USB-IF presented this two-day seminar in Taipei last November 2015. I’ve recently discovered the treasure trove of preso’s located here (Figure 1). The “USB Type-C Specification Overview” is the most comprehensive I’ve seen lately.

Figure 1: USB-IF held a “Developer Days” forum in Taipei November 2015. These PPT’s are a great place to start your USB 3.1/Type-C education. (Image courtesy: USB-IF.org.)

Figure 1: USB-IF held a “Developer Days” forum in Taipei November 2015. These PPT’s are a great place to start your USB 3.1/Type-C education. (Image courtesy: USB-IF.org.)

What is Type-C? Another decent 1,000-foot view is my first article on Type-C: “Top 3 Essential Technologies for Ultra-mobile, Portable Embedded Systems.” Although the article covers other technologies, it compares Type-C against the other USB connectors and introduces designers to the USB-IF’s Battery Charging (BC) and Power Delivery (PD) specifications.

What is USB? To go further back to basics, “3 Things You Need to Know about USB Switches” starts at USB 1.1 and brings designers up to USB 3.0 SuperSpeed (5 Gbps). While the article is about switches, it also reminds readers that at USB 3.0 (and 3.1) speeds, signal integrity can’t be ignored.

USB Plus What Else? The article “USB Type-C is Coming…” overlays the aforementioned information with Type-C’s sideband capabilities that can transmit HDMI, DVI, Thunderbolt and more. Here, the emphasis is on pins, lines, and signal integrity considerations.

More Power, Scotty! Type-C’s 100W Power Delivery sources energy in either direction, depending upon the enumeration sequence between host and target. Components are needed to handle this logic, and the best source of info is from the IC and IP companies. A recent Q&A we did with IP provider Synopsys “Power Where It’s Needed…” goes behind the scenes a bit, while TI’s E2E Community has a running commentary on all things PD. The latter is a must-visit stop for embedded designers.

Finally, active cables are the future as Type-C interfaces to all manner of legacy interfaces (including USB 2.0/3.0). At last year’s IDF 2015, Cypress showed off dongles that converted between specs. Since then, the company has taken the lead in this emerging area and they’re the first place to go to learn about conversions and dongles (Figure 2).

Figure 2: In the Cypress booth at IDF 2015, the company and its partners showed off active cables and dongles. Here, Type-C (white) converts to Ethernet, HDMI, VGA, and one more I don’t recognize. (Photo by Chris A. Ciufo, 2015.)

Figure 2: In the Cypress booth at IDF 2015, the company and its partners showed off active cables and dongles. Here, Type-C (white) converts to Ethernet, HDMI, VGA, and one more I don’t recognize. (Photo by Chris A. Ciufo, 2015.)

Evolving Future: Although USB 3.1 and the Type-C connector are solid and not changing much, IC companies are introducing more highly integrated solutions for the BC, PD and USB 3.1 specifications plus sideband logic. For example, Intel’s Thunderbolt 3 uses Type-C and runs up to 40 Gbps, suggesting that Type-C has substantial headroom and more change is coming. My point: expect to keep your USB 3.1 and Type-C education up-to-date.

PCI-SIG “nificant” Changes Brewing in Mobile

PCI-SIG Developers Conference, June 25, 2013, Santa Clara, CA

Of five significant PCI Express announcements made at this week’s PCI-SIG Developers Conference, two are aimed at mobile embedded.

From PCI to PCI Express to Gen3 speeds, the PCI-SIG is one industry consortium that lets no grass grow for long. As the embedded, enterprise and server industries roll out PCIe Gen3 and 40G/100G Ethernet, the PCI-SIG and its key constituents like Cadence, Synopsis, LeCroy and others are readying for another speed doubling to 16 GT/s (giga transfers/second) by 2015. The PCIe 4.0 next step evolves bandwidth to 16Gb/s or a whopping 64 GB/s (big “B”) total lane bandwidth in x16 width. PCIe 4.0 Rev 0.5 will be available Q1 2014 with Rev 0.9 targeted for Q1 2015.

Table of major PCI-SIG announcements at Developers Conference 2013

Table of major PCI-SIG announcements at Developers Conference 2013

Yet as “SIG-nificant” as this announcement is, PCI-SIG president Al Yanes said it’s only one of five major news items. The others include: a PCIe 3.1 specification that consolidates a series of ECNs in the areas of power, performance and functionality; PCIe Outside the Box which uses a 1-3 meter “really cheap” copper cable called PCIe OCuLink with an 8G bit rate; plus two embedded and mobile announcements that I’m particularly enthused about. Refer to the table for a snapshot.

New M.2 Specification

The new M.2 specification is a small, mobile embedded form factor designed to replace the previous “Mini PCI” in Mini Card and Half Mini Card sizes. The newer, as-yet-publicly-unreleased M.2 card will be smaller in size and volume but is intended to provide scalable PCIe performance to allow designers to tune SWaP and I/O requirements. PCI-SIG marketing workgroup chair Ramin Neshati told me that M.2 is part of the PCI-SIG’s increased focus on mobile.

The scalable M.2 card is designed as an I/O plug in for Bluetooth, Wi-Fi, WAN/cellular, SSD and other connectivity in platforms including ultrabook, tablet, and “maybe even smartphone,” said Neshati. At Rev 0.7 now, Rev 0.9 will be released soon and the final (Rev 1.0?) spec will become public by Q4 2013.

PCI-SIG M.2 card form factor

The PCI-SIG’s impending M.2 form factor is designed for mobile embedded ultrabooks, tablets, and possibly smartphones. The card will have a scalable PCIe interface and is designed for Wi-Fi, Bluetooth, cellular, SSD and more. (Courtesy: PCI-SIG.)

Mobile PCIe (M-PCIe)

Seeing the momentum in mobile and the interest in a PCIe on-board interconnect lead the PCI-SIG to work with the MIPI Alliance and create Mobile PCI Express: M-PCIe. The specification is now available to PCI-SIG members and creates an “adapted PCIe architecture” bridge between regular PCIe and MIPI M-PHY.

The Mobile PCI Express (M-PCIe) specification targets mobile embedded devices like smartphones to provide high-speed, on-board PCIe connectivity. (Courtesy: PCI-SIG.)

The Mobile PCI Express (M-PCIe) specification targets mobile embedded devices like smartphones to provide high-speed, on-board PCIe connectivity. (Courtesy: PCI-SIG.)

Using the MIPI M-PHY physical layer allows smartphone and mobile designers to stick with one consistent user interface across multiple platforms, including already-existing OS drivers. PCIe support is “baked into Windows, iOS, Android,” and others, says PCI-SIG’s Neshati.  PCI Express also has a major advantage when it comes to interoperability testing, which runs from the protocol stack all the way down to the electrical interfaces. Taken collectively, PCIe brings huge functionality and compliance benefits to the mobile space.

M-PCIe supports MIPI’s Gear 1 (1.25-1.45 Gbps), Gear 2 (2.5-2.9 Gbps) and Gear 3 (5.0-5.8 Gbps) speeds. As well, the M-PCIe spec provides power optimization for short channel mobile platforms, primarily aimed at WWAN front end radios, modem IP blocks, and possibly replacing MIPI’s own universal file storage UFS mass storage interface (administered by JEDEC).

M-PCIe by the PCI-SIG can be used in multiple high speed paths in a smartphone mobile device. (Courtesy: PCI-SIG and MIPI Alliance.)

M-PCIe by the PCI-SIG can be used in multiple high speed paths in a smartphone mobile device. (Courtesy: PCI-SIG and MIPI Alliance.)

PCI Express Ready for More

More information on these five announcements will be rolling out soon. But it’s clear that the PCI-SIG sees mobile and embedded as the next target areas for PCI Express in the post-PC era, while still not abandoning the standard’s bread and butter in PCs and high-end/high-performance servers.