Electronic apparatus and its control method, and accessory and its control method

An electronic apparatus attachable to and detachable from an accessory, the electronic apparatus comprising:

• a plurality of communication contacts that includes a first contact;
• at least one processor;
• and
• at least one memory coupled to the at least one processor storing instructions that, when executed by the at least one processor, cause the at least one processor to function as a control unit configured to control communication with the accessory via the plurality of communication contacts,
• wherein the control unit transmits a request for information indicating a communication factor in response to a notification of a communication request made when a signal level of the first contact changes from a first signal level to a second signal level different from the first signal level, and receives the information indicating the communication factor that causes the accessory to communicate with the electronic apparatus, in response to a transmission of the request for the information indicating the communication factor, and
• wherein in a case where the control unit is notified of the communication request via the first contact in response to a start of a power supply, the control unit performs predetermined communication without transmitting the request for the information indicating the communication factor or receiving the information indicating the communication factor.

A control method of an accessory that is attachable to and detachable from an electronic apparatus and includes a plurality of communication contacts that includes a first contact, the control method comprising the steps of:

• notifying the electronic apparatus of a communication request by changing a signal level of the first contact from a first signal level to a second signal level different from the first signal level;
• receiving a request for information indicating a communication factor that causes the accessory to communicate with the electronic apparatus;
• transmitting the information indicating the communication factor;
• and
• performing predetermined communication without the receiving step or the transmitting step in a case where the notifying step notifies the electronic apparatus of the communication request via the first contact in response to a start of a power supply.

A control method of an electronic apparatus that is attachable to and detachable from an accessory and includes a plurality of communication contacts that includes a first contact, the control method comprising the steps of:

• accepting a notification of a communication request made when a signal level of the first contact changes from a first signal level to a second signal level different from the first signal level;
• transmitting a request for information indicating a communication factor that causes the accessory to communicate with the electronic apparatus;
• receiving the information indicating the communication factor;
• and
• performing predetermined communication without the transmitting step or the receiving step in a case where the accepting step is made via the first contact in response to a start of a power supply.