Electronic device configured to update program stored therein using difference data and program updating method using difference data

A program updating method for, in an electronic device comprising a first microcomputer and a second microcomputer, the first microcomputer having a first storage configured to store a first program and a first controller configured to execute a first process for operating the first microcomputer by using the first program stored in the first storage, the second microcomputer having a second storage configured to store a second program different from the first program, a third storage configured to store the first program of which a version is identical to a current version of the first program stored in the first storage, a fourth storage configured to store first version information indicating the current version of the first program stored in the first storage, and a second controller configured to execute a second process for operating the second microcomputer by using the second program stored in the second storage, updating the first program stored in the first storage of the first microcomputer, the method comprising:

• acquiring, by the second controller of the second microcomputer, from a predetermined external device, difference data for updating the first program stored in the third storage, the difference data including second version information indicating a version of the first program after update by using the difference data;
• updating, by the second controller of the second microcomputer, the first program stored in the third storage by using the acquired difference data;
• updating, by the second controller of the second microcomputer, the first version information stored in the fourth storage with the second version information;
• transmitting, by the second controller of the second microcomputer, the updated first program stored in the third storage to the first microcomputer;
• storing, by the first controller of the first microcomputer, the updated first program transmitted from the second microcomputer in the first storage;
• and
• executing, by the first controller of the first microcomputer, the first process by using the updated first program,
• wherein the first microcomputer is a plurality of first microcomputers and the difference data includes information indicating one microcomputer to be updated among the plurality of first microcomputers,
• wherein the method further comprises:
• identifying, by the second controller of the second microcomputer, the one microcomputer to be updated based on the information upon acquiring the difference data, and
• wherein the updating the first program stored in the third storage includes updating, by the second controller of the second microcomputer, the first program stored in the first storage of the first identified one microcomputer.