Raspberry Pi 4 Revision Fixes USB-C Compatibility Problem

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The Raspberry Pi 4 is the most powerful Pi yet, but the $35, single-board PC has been plagued with a small USB-C compatibility issue since it launched last year. That problem should now be fixed in newly-produced versions of the board, as reported by The Register.

The problem had to do with the Pi 4's USB Type-C port, which it uses to receive power. The way that the port was constructed meant that it would not work with high-speed, "e-marked" cables. We tested a wide number of cables to see which would work, but found that most cables did not have any issues.

In short, if you have a USB 3.1 5 or 10 Gbps cable, chances are that it it is "electronically marked" while USB 2.0 cables are just fine. The high-speed cables require two pull down resistors on the Type-C port, because they use two lines to talk to the system. The original Pi 4 had only one resistor so these cables won't work with it. Considering that the Pi 4's USB-C port is only usable for charging, chances are that you wouldn't want to use a high-speed data cable with it anyway.

However, if you just happen to have high-speed USB Type-C cables lying around, you will now be able to use them to power your Raspberry Pi 4, if you have one of the newly-revised units that are selling now.

Unfortunately, it's not easy to tell whether you're getting one of the new Raspberry Pi 4 units before you buy it. In a quick look online, we didn't see any companies touting the new version.

We reached out to Raspberry Pi CEO Eben Upton to ask how users can tell whether they're purchasing a new revision board or an old model, and he said that the best way to tell is by testing the board with an electronically marked cable to see if it works. Presumably by the time you're doing that test, you've already bought your Pi so your best bet is to just assume that any new Raspberry Pi 4 you buy still has the compatibility problem.

However, all newly-manufactured Raspberry Pi 4s have the fix so eventually all the old inventory will be gone.