Why do you need a protocol for wireless charging
1. The transmitter board needs to confirm whether the receiving coil has been placed above the transmitting coil. If there is no receiving coil, the transmitting end does not work to reduce power consumption
2, if placed on the coil metal products will produce eddy currents leading to metal heat, such as the key on the launch plate then the key will heat, need to avoid this situation
3, the mobile phone charging current is different, such as normal charging 1A, fully charged when the current will drop to dozens of MA, then the transmitter power if constant, when the mobile phone is fully charged when the transmitter coil receiving voltage will be high, which is the reason for the load becomes smaller and the voltage rises, so when the load changes, the transmitter coil power also needs to be adjusted. It requires voltage feedback control just like switching power supplies