|61||iPhone 13 with USB-C and selective slow-charging
iPhones (and some other mobile Apple devices) have had the Lightning connector for almost a decade. While it has been the dream of many to have an iPhone with a USB-C connector, Apple will very likely not release iPhones with USB-C. A USB-C iPhone will increase interoperability and provide a universal charging standard (which is now used by iPads, MacBooks, Android Phones, many PCs and other devices).
Moreover, phone manufacturers have been competing for faster and faster charging speeds. The convenience of fast-charging comes at a significant cost to battery longevity. The faster we charge our phones, the more quickly its lithium cells wear out. To prevent premature battery failure from regular fast-charging, some phone manufacturers have added an option to charge batteries at an intentionally slow rate (when reasonable, such as when charging your phone overnight). iPhones don’t have this feature, but a USB-C iPhone can achieve selective slow-charging.
# Solution Overview
Our solution is to modify an iPhone 13-series smartphone. The modification entails removing the lightning receptacle inside the iPhone, adding electronics inside the iPhone for the proposed slow-charging functionality and the Lightning-to-USB-C conversion, and making mechanical changes to the iPhone chassis to accommodate and anchor a new USB-C receptacle.
# Solution Components
## Lightning to USB-C Conversion Logic
We will extract and use the components from the "C94" circuit on a certified Lightning to USB-C cable.
## USB-C slow-charging triggering and negotiation
* USB-C's orientation detection to enable/disable the slow-charging feature
* USB-C Power Delivery 3.0 controller to negotiate a maximum of 5V input from the charger.
## Custom Flex Cable
We will need to design a flexible PCB that houses all electronics where the iPhone has adequate internal space (potentially below the battery).
# Criterion for Success
* The modified iPhone charges with USB-C Power Delivery compatible chargers.
* The modified iPhone can transfer data over USB 2.0 bus, compatible with Apple's `libimobiledevice`.
* USB-C charging works in either direction/orientation.
* Plugging in the USB-C plug into the modified iPhone's receptacle in one orientation performs full-speed charging, while the other orientation leads to slow-charging.
* The modified iPhone still functions as intended.