USB-C Accessory with iOS 18

Question

nares OP

Created 5d

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Hello,

We have noted that our USB-C accessory now supplies power and data after a role-switch when it previously would initialize with supplying power to the iOS device, then move to just transferring data to the iOS device after a role-switch. The charging+data behavior is only seen when the accessory is connected to a USB-C based iOS device running iOS 18. Are there some updates in iOS 18 that would cause this behavior? We noted that the expected case occurs with USB-C devices running on the earlier versions (iOS 17 and below).

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Answer 1

DTS Engineer OP

Apple

3d

We have noted that our USB-C accessory now supplies power and data after a role-switch when it previously would initialize with supplying power to the iOS device, then move to just transferring data to the iOS device after a role-switch. The charging+data behavior is only seen when the accessory is connected to a USB-C based iOS device running iOS 18. Are there some updates in iOS 18 that would cause this behavior?

The basic answer is "yes, something changed". However, the real question here is how you accessory is configured? The change here is only a bug if your accessory is configured to no supply power- otherwise, the only (arguable) bug here is that iOS 17 wasn't drawing power it should have been using.

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Kevin Elliott
DTS Engineer, CoreOS/Hardware

1