M32CSLASH86 datasheet(418/505 Pages) RENESAS

418 / 505 page

Page 395

25. Flash Memory Version

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25.1.1 Boot Mode

The microcomputer enters boot mode when a hardware reset is performed while a high-level ("H") signal

is applied to the CNVSS and P50 pins and a low-level ("L") signal is applied to the P55 pin. A program in

the boot ROM area is executed.

In boot mode, the FMR05 bit in the FMR0 register selects access to either the boot ROM area or the user

ROM area.

In the factory setting, the rewrite control program for standard serial I/O mode is stored into the boot ROM

area.

The boot ROM area can be rewritten in parallel I/O mode only. If any rewrite control program using erase-

write mode 0 (EW mode 0) is written in the boot ROM area, the flash memory can be rewritten according

to the system implemented.

25.2 Functions to Prevent the Flash Memory from Rewriting

The flash memory has the ROM code protect function for parallel I/O mode and the ID code verify function

for standard I/O mode to prevent the flash memory from reading or rewriting.

25.2.1 ROM Code Protect Function

The ROM code protect function prevents the flash memory from reading and rewriting in parallel I/O

mode.

Figure 25.2 shows the ROMCP register. The ROMCP register is located in the user ROM area.

The ROM code protect function is enabled when the ROMCP1 bit is set to "002", "012" or "102".

25.2.2 ID Code Verify Function

Use the ID code verify function in standard serial I/O mode. The ID code sent from the serial programmer

is compared with the ID code written in the flash memory for a match. If the ID codes do not match,

commands sent from the serial programmer are not accepted. However, if the four bytes of the reset

vector are "FFFFFFFF16", ID codes are not compared, allowing all commands to be accepted.

The ID codes are 7-byte data stored consecutively, starting with the first byte, into addresses

0FFFFDF16, 0FFFFE316, 0FFFFEB16, 0FFFFEF16, 0FFFFF316, 0FFFFF716 and 0FFFFFB16. The flash

memory must have a program with the ID codes set in these addresses.

M32C/86 Datasheet(PDF) 418 Page - Renesas Technology Corp