Raspberry Pi 4: Beware of the USB-C Power Supply Bug!

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This article is authorized to be reproduced from Open Source China (ID: oschina2013)

The Raspberry Pi 4 Model B was released two weeks ago. As the latest generation of Raspberry Pi products, the Pi 4 has improved performance (officially claimed to have desktop performance comparable to entry-level x86 PC systems) and has become more versatile and practical in terms of commonly used interfaces. The Pi 4 includes two USB 2 ports, two USB 3 ports,powered by a USB-C port, and also provides a Gigabit Ethernet port and a headphone jack, along with two micro HDMI ports (supporting two 4K displays).

However, recently developer Tyler discovered an issue with the USB-C power supply interface of the Raspberry Pi 4. According to this developer’s description, the USB-C charging interface of the Pi 4 is not compatible with all USB Type-C cables that should be supported, meaning that users may not be able to charge the Raspberry Pi 4 with the Type-C data cable they have on hand.

Subsequently, the Raspberry Pi Foundation confirmed that the USB-C interface of the Pi 4 has a design flaw and is not compatible with all USB Type-C data cables.

According to the circuit diagram published by the foundation, it lacks a CC resistor, while both “CC” pins on the Pi 4 USB-C port should have their own 5.1K ohm resistors. This design flaw ultimately causes them to share a single resistor, compromising compatibility with many USB-C chargers.

USB-C is a complex connector, and some of its cables use electronic markers, which means they contain integrated chips to support various devices. For example, we can use the charger from a MacBook Pro to power various devices with USB-C ports, and the charger automatically determines how much power to deliver.

However, due to the design flaw of the Raspberry Pi 4, it does not support electronically marked cables, such as Apple’s Type-C data cable or the data cable for Google Pixel 3, which are incorrectly identified as audio adapter accessories.

Fortunately, this design flaw will not damage the Raspberry Pi 4, and there is no fire hazard; it just makes charging inconvenient.

As the first Raspberry Pi device to support USB-C, it is regrettable that such a design flaw has occurred, but as users, we currently have to use workaround methods to resolve this issue. A relatively simple method is to purchase cables or chargers without electronic markers, such as the USB-C charger that the Raspberry Pi Foundation is selling (priced at $8).

Eben Upton, co-founder of Raspberry Pi, stated that future circuit boards will fix this flaw, but existing users can only adopt workaround methods. He also mentioned that surprisingly, this issue was not discovered during extensive testing.