R8CSLASH20 datasheet(396/501 Pages) RENESAS

396 / 501 page

R8C/20 Group, R8C/21 Group

19. Flash Memory

Rev.2.00 Aug 27, 2008

Page 380 of 458

REJ09B0250-0200

19.3

Functions to Prevent Rewriting of Flash Memory

Standard serial I/O mode contains an ID code check function, and the parallel I/O mode contains a ROM code

protect function to prevent the flash memory from reading or rewriting easily.

19.3.1

ID Code Check Function

Use this function in standard serial I/O mode. Unless the flash memory is blank, the ID codes sent from the

programmer and the ID codes written in the flash memory are determined whether 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, the areas of which, beginning with the first byte, are 00FFDFh, 00FFE3h, 00FFEBh, 00FFEFh, 00FFF3h,

00FFF7h, and 00FFFBh. Write a program in which the ID codes are set at these addresses and write them in the

flash memory.

Figure 19.3

Address for Stored ID Code

4 bytes

Address

00FFDFh to 00FFDCh

Undefined instruction vector

NOTE:

1. The OFS register is assigned to 00FFFFh. Refer to

Figure 19.4 OFS Register for the OFS register

details.

Overflow vector

00FFE3h to 00FFE0h

00FFE7h to 00FFE4h

BRK instruction vector

Address match vector

00FFEBh to 00FFE8h

00FFEFh to 00FFECh

Oscillation stop detection/watchdog

timer/voltage monitor 2 vector

00FFF3h to 00FFF0h

00FFF7h to 00FFF4h

Address break

00FFFBh to 00FFF8h

Reset vector

00FFFFh to 00FFFCh

(Reserved)

ID1

ID2

ID3

ID4

ID5

ID6

ID7

(1)

Single step vector

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