M16C User Manual.pdf

ProtectMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER2.1 Protect2.1.1 Overview'Protect' is a function that causes a value held in a register to be unchanged even when a program runsaway. The following is an overview of the protect function:(1) Registers affected by the protect functionThe registers affected by the protect function are:(a) System clock control registers 0, 1 (addresses 000616 and 000716)(b) Processor mode registers 0, 1 (addresses 000416 and 000516)(c) Port P9 direction register (address 03F316), SI/Oi control register (i=3,4)(addresses 036216 and036616)The values in registers (1) through (3) cannot be changed in write-protect state. To change values inthe registers, put the individual registers in write-enabled state.(2) Protect registerFigure 2.1.1 shows protect register.276