USB is regarded as the world’s most popular serial interface, with over 1 billion devices shipping every year. This means there are a lot of players in the market, and many possible applications. From mice to mobile application processors, through set-top boxes and video cameras, it’s actually hard to imagine a device that is not USB-connected. How then should a designer make a decision today, that will not make his product outdated in the future when it enters the market? What’s the price of future-proofing the design, and is it always worth it? I came up with three simple questions that every designer should ask himself to make sure he designs his application not only for the market of today, but also for tomorrow—questions that a USB application designer needs to answer for himself before he starts looking for IP:
1. What is the target speed for my USB interface?
Over the years, USB has improved performance nearly 10000 times. Yes, 10000! USB 1.0 Low Speed offers maximum throughput of 1.5Mbps, while USB 3.1 is now expected to reach 10Gbps (all being theoretical values). Fortunately, there are three values in between that make perfect intermediate steps—USB 1.1 Full Speed at 12Mbps (perfect for peripherals, fitness bands, or low-bandwidth IoT devices), USB 2.0 High Speed at 480Mbps (pen drives, low-end smartphones, and tablets), and USB 3.0 at 5Gbps (mid- to high-level application processors, high performance SSDs, video cameras).
2. What roles do I need my application to operate in?
While most protocols give options between Master (Host) and Slave (Peripheral) modes, USB offers two additional kinds of devices—namely Dual-Role/On-The-Go and Hub. Dual-Role/OTG controller offers the functionality of both Host and Device controllers, and can switch between them either by firmware (typical for Dual-Role), or by hardware (support for OTG protocols). Hub controllers serve as extension cords—they multiply the number of available downstream ports while using a single upstream port to connect to a Host controller or another Hub that is in between.
3. What technology will I design my product in?
The answer to this question is not necessarily driven by the speed of USB interface, but it is very common that the more advanced the technology, the faster the USB interface (and the higher price of the end product, of course). As of today, we can see a lot of deployment for USB 1.0/1.1 in 55/65nm nodes, USB 2.0 occupies 40nm and starts to move to 28nm, and USB 3.0 moves from 28nm to 16nm. USB 3.1 solutions will most probably start largely at 16nm/14nm and move to 10nm when both technologies (3.1 and 10nm) get more mature.
At Cadence, we offer one of the most comprehensive USB IP portfolios available in the market, covering all USB device functions and all popular PHY technologies. From Peripheral Device and Host controllers to Dual-Role/OTG and Hub controllers, Cadence offers a complete suite of products for USB 1.0/1.1, 2.0, and 3.0 applications. PHY IP is available also for all USB standards, on processes from 65nm to 16FF+, following the segmentation presented above. Many controller/PHY combinations are certified by USB-IF as integrated solutions and deployed by major customers worldwide. To find out more about Cadence USB IP, please contact your Cadence IP sales representative or check our dedicated USB IP website.
Jacek Duda