Method for automatically adjusting a piece of time information on a watch

A method for adjusting a timepiece including a case, including a bracelet, in which a microcontroller powered by a cell stack or battery is arranged, the microcontroller including a time base and memory areas and used to send control signals to a display to display at least one piece of time information, the method comprising:

• testing accuracy of a piece of time information of the timepiece by using a camera of a portable object to compare with a piece of time information obtained from an external source, the portable object including a screen and a second case in which there is electronic circuitry including a second microcontroller, a second display, the camera, and a communication circuit, the electronic circuitry being powered by a second battery;
• sending the time information from the portable object to the timepiece when a difference is detected, the timepiece including at least one phototransistor arranged on the case for receiving the time information, the timepiece configured to operate the display to display a correct time information;
• and
• checking that the correct time information is displayed,
• wherein the sending the time information from the portable object to the timepiece further comprises:
• defining, on the screen of the portable object, an area of shape and dimensions similar to the case of the timepiece,
• instructing the case of the timepiece to be held against the defined area, and
• sequentially displaying black or white in an entirety of the area or an entirety of a portion of this area, in a sequence of black and white corresponding to a luminous coding of the time information.