An adapter can be used to connect a portable electronic device to an accessory in instances where the portable electronic device and the accessory have incompatible connectors. The adapter provides two connectors, one compatible with the portable electronic device and the other compatible with the accessory. The adapter has several modes of operation. The portable electronic device selects the appropriate mode of operation for the adapter once it receives information about the accessory connected to the adapter. The portable electronic device instructs the adapter to switch to the selected mode and in response the adapter configures its internal circuitry to enable the selected mode. The portable electronic device can then communicate with the accessory via the adapter. The presence of the adapter can be transparent to the accessory.