Write protection for EEPROM in electronic control system

摘要

An electronic control system (1) has inputs from a speed sensor (2), temperature sensor (3) and a displacement sensor (4). The inputs are digitised (18) and entered into a microcomputer (10) that receives data from an EEPROM memory (12). An interface (21) connects a diagnostics unit (7) with the microcomputer and outputs are generated to solenoid valves (5) and indicators. The EEPROM has a region of memory defined by the manufacturer as being protected and cannot be accessed. A flag indicates the region. A further region may be selected by the user as being protected.