Saturday, 22 Sep 2018

HDMI over USB-C: What’s a development kit?

Cypress recently announced that they have a solution for HDMI over USB-C. This is not about a consumer product but we thought it might be interesting to explain a bit more about this.

Cypress is a company that sells ICs (chips) for a number of purposes: on their product page, they list ICs for WiFi, touch screens, embedded CPUs, memory and a number of USB-related ICs. Other companies can buy these ICs and make a product out of it. Cypress tries to make that as easy as possible: they’ll provide an IC, a design for a PCB (electronics board) and a bunch of documentation. This is done in the form of a development kit. So let’s look at the CCG3 development kit, annotated for your pleasure:

Annotated version of the CCG3 evaluation kit

So what you see here, is that they’ll give you actual, working electronics with their IC on it. It’s your job as a manufacturer to make that into a product. So you look at the board and its design, which is often called a “reference design”. Cypress is not in the business of PCBs, they just want to sell ICs. So you can copy that board as-is or change things like adding or removing stuff. For example, you could remove debug connectors and further optimize the board layout for space if you want to make a smaller end product.

So what’s on the picture? Besides a couple of cables, a little USB-A-to-USB-C dongle and a power supply, you’ll see the biggest board which is common to all their CCGx development kits. They call that the base board. A smaller so-called daughter board is connected to it. That daughter board can’t do anything on its own — it’s controlled via the base board. That contains the actual IC they’re trying to sell here, the CCG3.

So what does it do? The easiest thing to find out, is go to the Cypress website’s page of the development kit. At the bottom of the page, there’s a bunch of PDFs. The Quick Start has a nice close-up:

Details of base and daughter board
Details of base and daughter board, click to embiggen

That’s the hardware side of things. The User Guide has a nice schematics of what the CCG3 actually does:

So on the input side, we have a PC with USB 3 and DisplayPort. On the output side, we have a Type-C port. So this is really useful if you’re a maker of laptops, media PCs, set-top boxes or consoles. You used to just have ports for USB and DisplayPort on the outside. And with this solution, you just put the CCG3 chip on your motherboard, route the lines of your USB 3 and DisplayPort to the CCG3 IC and route them to a USB-C port on the outside.

Now the news is, that the CCG3 can also be used in a USB-C to HDMI cable, as displayed on their page Native HDMI over Type-C Alternate Mode:

Cypress CCG3: native HDMI over Type-C Alternate Mode

So which manufacturer actually uses this particular IC? I couldn’t find cables/devices which use this one, but if you search for “Cypress” on the iFixit site, you’ll find plenty of examples where their stuff is used: MacBooks, FitBit, PlayStation 4, Mac Mini et cetera.

We haven’t tested any of these USB-C to HDMI cables yet, but you’re welcome to take a look at our USB-C to DisplayPort cables.