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M16C/5L Group, M16C/56 Group
26.5
Flash Memory Rewrite Disable Function
This function disables the flash memory from being read, written, and erased. The following are details for
each mode:
Parallel I/O mode
ROM code protect function
Standard serial I/O mode
ID code check function, forced erase function, and standard serial I/O mode disable function
26.6
Boot Mode
A hardware reset occurs while a high-level signal is applied to pins CNVSS. After reset, the MCU enters
boot mode. In boot mode, user boot mode or standard serial I/O mode is selected in accordance with the
content of the user boot code area. Refer to 26.9 "Standard Serial I/O Mode" for details.
The MCU does not enter boot mode in power-on reset and voltage monitor 0 reset.
26.7
User Boot Mode
This mode is used for starting the flash memory rewrite program programmed by a user.
Allocate the flash memory rewrite program to program ROM 2. In user boot mode, the program is
executed from address 10000h (starting address of program ROM 2). After starting the program, the flash
memory is rewritten according to the program in EW0 or EW1 mode.
26.7.1
User Boot Function
User boot mode can be selected by the status of a port when the MCU starts in boot mode. Table 26.6
lists the User Boot Function Specifications.
Table 26.6
User Boot Function Specifications
Item
Entry pin
User boot start level
User boot start address
Set "UserBoot" in ASCII code to addresses 13FF0h to 13FF7h in the user boot code area, select a port
for entry from addresses 13FF8h to 13FF9h and 13FFAh, and select the start level with address
13FFBh. After starting boot mode, user boot mode or standard serial I/O mode is selected in
accordance with the input level of the selected port.
In addition, if addresses 13FF0h to 13FF7h are set to "UserBoot" in ASCII code and addresses 13FF8h
to 13FFBh are set to 00h, user boot mode is selected.
In user boot mode, the program of address 10000h (program ROM 2 start address) is executed.
Figure 26.3 shows the User Boot Code Area, Table 26.7 lists Start Mode (When Port Pi_j is Selected for
Entry), Table 26.8 lists "UserBoot" in ASCII Code, and Table 26.9 lists Addresses of Selectable Ports for
Entry.
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
None or select a port from P0 to P3, P6 to P10
Select high or low
Address 10000h (program ROM 2 start address)
Specification
26. Flash Memory
Page 661 of 803
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