| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely rewrite a control program and the control data which are contained in every microcomputer in a simple constitution by inhibiting the transfer of data to the communication lines of other microcomputers while a certain microcomputer is executing the write processing. SOLUTION: The microcomputers 18 and 26 receive the write voltage VPP from a power circuit 34 when they start their operations in the reset states after an ignition switch IGS is turned on. Then the microcomputers 18 and 26 receive the write data from a memory writing device 4 and write the data in a flash memory after updating them when the identification codes sent from the device 4 are coincident with their own ones respectively. If no coincidence is confirmed between both identification codes, the microcomputers 18 and 26 decides that other microcomputers are executing the write processing for rewrite of data. Thus, the microcomputers 18 and 26 cut off the switch elements and compulsively inhibit the communication to their own serial communication lines 32.</p> |
