M16C User Manual.pdf

Appendix Standard Serial I/O Mode (Flash Memory Version)Mitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERData Protection (Block Lock)Each of the blocks in Figure 1.30.1 have a nonvolatile lock bit that specifies protection (block lock) againsterasing/writing. A block is locked (writing “0” for the lock bit) with the lock bit program command. Also, thelock bit of any block can be read with the read lock bit status command.Block lock disable/enable is determined by the status of the lock bit itself and execution status of the lockbit disable and lock enable bit commands.(1) After the reset has been cancelled and the lock bit enable command executed, the specified blockcan be locked/unlocked using the lock bit (lock bit data). Blocks with a “0” lock bit data are lockedand cannot be erased or written in. On the other hand, blocks with a “1” lock bit data are unlockedand can be erased or written in.(2) After the lock bit enable command has been executed, all blocks are unlocked regardless of lock bitdata status and can be erased or written in. In this case, lock bit data that was “0” before the blockwas erased is set to “1” (unlocked) after erasing, therefore the block is actually unlocked with thelock bit.0C000016Block 6 : 64K byte0D000016Block 5 : 64K byte0E000016Block 4 : 64K byteFlash memorysize256K byteFlash memorystart address0C0000160F0000160F8000160FA000160FC000160FFFFF16Block 3 : 32K byteBlock 2 : 8K byteBlock 1 : 8K byteBlock 0 : 16K byteUser ROM areaFigure 1.31.18. Blocks in the user area266