Raspberry Pi 4 does not receive power via USB-C connection with cable with e-marker
The recently announced Raspberry Pi 4 appears to have a problem with certain USB-C cables. As soon as a cable with an e-marker is used, the motherboard receives no power. Eben Upton, co-founder of the Raspberry Pi Foundation, has said.
Eben Upton has admitted to TechRepublic that not every USB-C cable will work with the Raspberry Pi 4. “A smart charger with a cable with an e-marker will incorrectly identify the Raspberry Pi 4 as an audio adapter accessory and refuse to supply power. I expect this to be fixed in a future revision, but for now users should apply a workaround Surprisingly, this didn’t show up in our testing program,” said Upton.
He refers to a technical analysis by Tyler Ward, which shows that the Raspberry Pi 4 has not adopted the official USB-c specification, but has applied its own design. The Raspberry Pi Foundation has used a single resistor for both the CC1 and CC2 connection pins. The two pins are not each given their own 5.1kΩ resistor, but share one. This presents problems with cables with an e-marker, as these cables use both CC connections.
Cables equipped with an e-marker have a chip built into the cable and transmit the maximum current. For example, this chip indicates to a connected device that the cable supports the USB power delivery protocol and provides specifications about the cable. These cables are used, for example, by laptops.
The only solution to this problem is to omit the cables in question with an e-marker. Among other things, the cables that are supplied with smartphones can offer a solution, provided the power supply meets the 5.1V/3A requirements of the board. The official charger from the Raspberry Pi Foundation also offers a solution. Ars Technica has checked with Raspberry Pi Foundation when a charging connection made according to the official specification will be released. The company says that will happen “in the next few months.”
The Raspberry Pi 4 was announced at the end of last month and includes a Cortex A72 quadcore, USB 3.0 connections, 1 to 4GB of RAM and a power supply that runs via USB-C. It was recently announced that the board will receive new firmware to lower the temperature.