The Raspberry Pi 4 launched in late June and as usual, it’s a major upgrade over the prior model, packing more RAM, enough graphics horsepower to drive a pair of 4K displays, and USB-C charging instead of micro-USB. But there’s a problem: The USB-C charging doesn’t work with some USB-C chargers.
Compatibility woes are nothing new with USB-C, but in this case, the problem lies with the Pi. As first described by Tyler Ward, the Raspberry Pi 4 uses “incorrect detection circuitry on the Pi end of the USB connection.” The $35 micro-PC shares a single resistor for two of the USB-C port’s pins, while the official USB-C spec calls for each pin to get a resistor of its own. 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 Raspberry Pi 4 detects e-marked cables as an audio adapter accessory rather than a charger and refuses to use them to power up the board. USB-C issues aren’t an unheard-of problem, as the Nintendo Switch also packs a non-standard USB-C port that won’t work with all cables, and early phones and laptops equipped with USB-C charging could be fried by rogue cables.
“Instead of trying to come up with some clever circuit, hardware designers should simply copy the figure from the USB-C Spec exactly. The Figure 4–9 I posted above isn’t simply a rough guideline of one way of making a USB-C receptacle. It’s actually normative, meaning mandatory, required by the spec in order to call your system a compliant USB-C power sink. Just copy it.”
Leung also says the Raspberry Pi team should’ve tested e-marked cables before shipping the board, as MacBook chargers aren’t exactly a rarity. “Raspberry Pi, you can do better,” he pleaded. “I urge you to correct your design as soon as you can so you can be USB-C compliant.”
Fortunately, it sounds like that correction is already in the works. Pi co-creator Eben Upton told Tech Republic that he expects “this will be fixed in a future board revision,” and a Pi spokesperson confirmed to Ars Technica that a board revision with a compliant USB-C charging port should roll out in the “next few months.”
If you’ve already bought a Raspberry Pi 4, you can work around the charging issue by not using an e-marked cable. Options include using a USB-C phone charger, or picking up the official Raspberry Pi USB-C power supply for $8. It’s a shame that such a great piece of kit is suffering from such an easily avoided issue, but this isn’t the end of the world.
Brad Chacos spends his days digging through desktop PCs and tweeting too much. He specializes in graphics cards and gaming, but covers everything from security to Windows tips and all manner of PC hardware.