M37544 RENESAS [Renesas Technology Corp], M37544 Datasheet - Page 48

• Manufacturer Part Number: M37544
• Description: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
• Manufacturer: RENESAS [Renesas Technology Corp]

Rev.1.04
REJ03B0012-0104Z
7544 Group
ROM Code Access Protection
We would like to support a simple ROM code protection function
that prevents a party other than the ROM-code owner to read and
reprogram the builit-in PROM code of the MCU.
The MCU has 7 bytes of dedicated ROM spaces in address
0xFFD4 to 0xFFDA, as an ID-code (referred to as “the ID-code”)
enabling a Programmer to verify with the input ID-code and
validate further operations.
Expected Programmer ID-Code Verification
Function
First, Programmer must check the ID-code of the MCU.
If the ID-code is still in blank, Programmer enables all operations,
Read, Program, and Program-Verify.
When Programmer programs the MCU, Programmer also
programs the given ID-code as well as the actual firmware.
If the ID-code is not blank, Programmer verifies it with the input
ID-code.
When the ID-codes don't match, Programmer will reject all further
operations.
If they match, Programmer perform operations according to the
given command.
2004.06.08
page 48 of 66
Fig. 63 ROM-Code Protection ID Location
Address
FFDA
FFD4
FFD5
FFD6
FFD7
FFD8
FFD9
16
16
16
16
16
16
16
ID1
ID2
ID3
ID4
ID5
ID6
ID7