Tuesday, 24 November, 2020

Raspberry Pi 4 Is Not Compatible with All Type-C Cables

Raspberry Pi PoE HAT Raspberry Pi supremo Eben Upton talks to The Reg about Pi PoE woes READ MORE
Cecil Davis | 10 July, 2019, 22:15

Cutting corners: Cutting corners has seemingly backfired on the Raspberry Pi Foundation as its newest product, the Pi 4, has been confirmed to feature a non-compliant USB-C implementation that tampers with compatibility.

The Raspberry Pi Foundation recently launched the fourth iteration of its immensely popular single-board computer, the Raspberry Pi 4 Model B. Soon after, several units purchased by eager buyers failed to power up through the USB Type C port.

E-marking is a technique which gives a cable a digital signature based on what the cable is going to do. Fully compliant ones used by higher voltage devices like laptops will identify the Raspberry Pi 4 as an audio device and won't power it.

The bad news is that there's not a lot the team can do about this until the next hardware revision - the quirk is built into the hardware.

Upton added that he was surprised that the issue did not show up in its testing program, which he claims is "quite extensive".

If you've already bought a Raspberry Pi 4 and are facing this problem yourself, the only solution is to use non-e-marked USB-C cables that can deliver a 5.1V/3A power supply. Sadly, in-depth analysis of the board and its design revealed that the Foundation used a more cost-efficient design over compliance with the spec.

Corbyn calls on new Tory leader to hold second Brexit referendum
The announcement was welcomed by Tom Watson, the Labour Party's deputy leader, who claimed "Remain is who we are". Labour had accepted the referendum result in its 2017 general election manifesto.

Instead of trying to come up with some clever circuit", Leung writes, "hardware designers should simply copy the figure from the USB-C Specexactly [emphasis his] The Figure 4-9 I posted above isn't simply a rough guideline of one way of making a USB-C receptacle. This non-compliant design breaks functionality with more powerful "e-marked" cables, such as the USB-C chargers that ship with Apple's MacBooks and some Windows 10 laptops.

The developers behind Kali Linux agree and have made it so that their distribution is compatible with Raspberry Pi 4 and has "on-board wifi monitor mode & frame injection support".

Perhaps the most notable change was the move to USB Type-C for power. The Raspberry Pi 4 now only uses one, which is why it is being detected as an audio adapter.

Benson Leung, a Google Chrome OS engineer, has always been fighting for a stricter and more uniform testing and approval standard for USB Type C cables and chargers. The system doesn't power up. "The Raspberry Pi 4 is actually a pretty unbelievable little machine", said Offensive Security.

An easy workaround is to buy a non-e-marked cable or charger. As a result, the cable doesn't supply power, and your Raspberry Pi won't start up.