MICROCOMPUTER AND SECURITY SETTING SYSTEM

PROBLEM TO BE SOLVED: To appropriately switch over between activation and deactivation of a security function depending on a stage of reprogramming.SOLUTION: Security setting flags 5 and 6 are provided in both a rewritable area 3 and a non-rewritable area 4 of a nonvolatile memory 2 of a microcomputer 1, respectively, and a security function is switched over between activation and deactivation depending on set values of the respective security setting flags 5 and 6. At a time of reprogramming during development, the security setting flag 6 in the non-rewritable area 4 is set in an OFF-state and the security setting flag 5 in the rewritable area 3 is switched over between ON-setting and OFF-setting, thereby switching the security function over between activation and deactivation. At a time of reprogramming during mass production, the security setting flag 6 in the non-rewritable area 4 is set in an ON-state (fixed to an ON-state) so as to effectively continue to maintain the security function. 【課題】リプロを行う段階に応じてセキュリティ機能の有効と無効とを適切に切替える。【解決手段】マイクロコンピュータ１の不揮発性メモリ２の書換え領域３と非書換え領域４との双方に、それぞれセキュリティ設定フラグ５、６を設け、それぞれの設定値により、セキュリティ機能の有効と無効とを切替える。開発時のリプロでは、非書換え領域４のセキュリティ設定フラグ６をオフ設定とし、書換え領域３のセキュリティ設定フラグ５をオン設定とオフ設定との間で切替えることで、セキュリティ機能の有効と無効とを切替える。量産時のリプロでは、非書換え領域４のセキュリティ設定フラグ６をオン設定（オン固定）とし、セキュリティ機能を有効に維持し続ける。【選択図】図１