M16C26A Datasheet, PDF (252/352 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/Tiny SERIES

M16C/26A Group (M16C/26A, M16C/26B, M16C/26T)
17. Flash Memory Version
17.3 Functions To Prevent Flash Memory from Rewriting
The flash memory has a built-in ROM code protect function for parallel I/O mode and a built-in ID code
check function for standard input/output mode to prevent the flash memory from reading or rewriting.
17.3.1 ROM Code Protect Function
The ROM code protect function disables reading or changing the contents of the on-chip flash memory in
parallel I/O mode. Figure 17.3.1.1 shows the ROMCP address. The ROMCP address is located in a user
ROM area.
To enable ROM code protect, set the ROMCP1 bit to “002”, “012”, or “102” and set the bit 5 to bit 0 to
“1111112”.
To cancel ROM code protect, erase the block including the the ROMCP address in CPU rewrite mode or
standard serial I/O mode.
17.3.2 ID Code Check Function
Use the ID code check function in standard serial input/output mode. Unless the flash memory is blank,
the ID codes sent from the programmer and the seven bytes ID codes written in the flash memory are
compared to see if they match. If the ID codes do not match, the commands sent from the programmer
are not acknowledged. The ID code consists of 8-bit data, starting with the first byte, into addresses,
0FFFDF16, 0FFFE316, 0FFFEB16, 0FFFEF16, 0FFFF316, 0FFFF716, and 0FFFFB16. The flash memory
has a program with the ID code set in these addresses.
Rev. 2.00 Feb.15, 2007 ^{page 235} of 329
REJ09B0202-0200