I'm not an iPhone user so bear that in mind...
I'm assuming you're connect your Pi to the USB A port not the lightning port of the adapter.
First thing I'd do is try without that adapter but that'll likely need either a USB C to lightning cable or a USB C male to USB A female adpater and a "normal" USB A to lightning cable.
I'd expect a dumb adapter to have all the +5V pins directly connected togther so the first thing I'd try is cutting/blocking the power wire in the USB cable between adapter and Pi. Doing so removes any chance of power flowing in the wrong direction.
Next I'd try running the 4B from the iphone with a normal A male to C male cable.and no PSU to the 4B. If you are certain that the iPhone charger won't deliver more thatn 5V you could try connecting that to the adapter too. Be aware that a 4B needs 600mA for itself under normal load, more under high load or with USB devices drawing power from it.
If it does turn out to be a power issue, and you don't need the CPU performace of a 4B the zero series needs much less power (~150mA) and can do USB gadget stuff.
I'm assuming you're connect your Pi to the USB A port not the lightning port of the adapter.
First thing I'd do is try without that adapter but that'll likely need either a USB C to lightning cable or a USB C male to USB A female adpater and a "normal" USB A to lightning cable.
I'd expect a dumb adapter to have all the +5V pins directly connected togther so the first thing I'd try is cutting/blocking the power wire in the USB cable between adapter and Pi. Doing so removes any chance of power flowing in the wrong direction.
Next I'd try running the 4B from the iphone with a normal A male to C male cable.and no PSU to the 4B. If you are certain that the iPhone charger won't deliver more thatn 5V you could try connecting that to the adapter too. Be aware that a 4B needs 600mA for itself under normal load, more under high load or with USB devices drawing power from it.
If it does turn out to be a power issue, and you don't need the CPU performace of a 4B the zero series needs much less power (~150mA) and can do USB gadget stuff.
Statistics: Posted by thagrol — Wed Feb 21, 2024 12:51 am