M16C/62 Group DATASHEET

CPU Rewrite Mode (Flash Memory Version)Mitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTERCPU Rewrite ModeIn CPU rewrite mode, the on-chip flash memory can be operated on (read, program, or erase) under controlof the Central Processing Unit (CPU).In CPU rewrite mode, only the user ROM area shown in Figure 1.28.1 can be rewritten; the boot ROM areacannot be rewritten. Make sure the program and block erase commands are issued for only the user ROMarea and each block area.The control program for CPU rewrite mode can be stored in either user ROM or boot ROM area. In the CPUrewrite mode, because the flash memory cannot be read from the CPU, the rewrite control program mustbe transferred to any area other than the internal flash memory before it can be executed.Microcomputer Mode and Boot ModeThe control program for CPU rewrite mode must be written into the user ROM or boot ROM area inparallel I/O mode beforehand. (If the control program is written into the boot ROM area, the standardserial I/O mode becomes unusable.)See Figure 1.28.1 for details about the boot ROM area.Normal microcomputer mode is entered when the microcomputer is reset with pulling CNVSS pin low. Inthis case, the CPU starts operating using the control program in the user ROM area.When the microcomputer is reset by pulling the P55 pin low, the CNVSS pin high, and the P50 pin high, theCPU starts operating using the control program in the boot ROM area. This mode is called the “boot”mode. The control program in the boot ROM area can also be used to rewrite the user ROM area.Block AddressBlock addresses refer to the maximum even address of each block. These addresses are used in theblock erase command, lock bit program command, and read lock status command.236