Functions To Prevent Flash Memory From Rewriting; Rom Code Protect Function; Id Code Check Function - Renesas M16C FAMILY series Hardware Manual
16-bit single-chip microcomputer
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- User manual (380 pages) ,
- Hardware manual (257 pages) ,
- User manual (369 pages)
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18.3 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.
18.3.1 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 18.5 shows the ROMCP address. The ROMCP address is located in a user
ROM area. To enable ROM code protect, set the ROMCP1 bit to "00
bit 0 to "111111
".
2
To cancel ROM code protect, erase the block including the the ROMCP1 register in CPU rewrite mode or
standard serial I/O mode.
18.3.2 ID Code Check Function
Use the ID code check function in standard serial input/output mode. Unless the flash memory is blank,
the ID code sent from the programmer and the 7-byte ID code written in the flash memory are compared
for 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, 0FFFDF
0FFFEB
, 0FFFEF
16
with the ID code set in these addresses.
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, 0FFFF3
, 0FFFF7
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f o
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5
, and 0FFFFB
. The flash memory must have a program
16
16
18. Flash Memory Version
", "01
", or "10
" and set the bit 5 to
2
2
2
16
, 0FFFE3
,
16
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