Renesas M16C/6NK Manual De Usuario

Rev.1.10    Jul 01, 2005    page 59 of 318
REJ09B0124-0110

M16C/6N Group (M16C/6NK, M16C/6NM)

8. Protection

This document is under development and its contents are subject to change.

In the event that a program runs out of control, this function protects the important registers so that they will

not be rewritten easily. Figure 8.1 shows the PRCR register. The following lists the registers protected by the

PRCR register.

• The PRC0 bit protects the CM0, CM1, CM2, PLC0, PCLKR and CCLKR registers;

• The PRC1 bit protects the PM0, PM1, PM2, TB2SC, INVC0 and INVC1 registers;

• The PRC2 bit protects the PD7, PD9, S3C, S4C, S5C and S6C registers 

(1)

.

NOTE:

1. The S5C and S6C registers are only in the 128-pin version.

Set the PRC2 bit to “1” (write enabled) and then write to any address, and the PRC2 bit will be set to “0” (write

protected). The registers protected by the PRC2 bit should be changed in the next instruction after setting

the PRC2 bit to “1”. Make sure no interrupts or DMA transfers will occur between the instruction in which the

PRC2 bit is set to “1” and the next instruction. The PRC0 and PRC1 bits are not automatically set  to “0” by

writing to any address. They can only be set to “0” in a program.

RW

RW

RW

RW

PRC1

PRC0

PRC2

Protect Bit 1

Protect Bit 0

Protect Bit 2

Enable write to CM0, CM1, CM2, 
PLC0, PCLKR, CCLKR 
registers
  0 : Write protected
  1 : Write enabled
Enable write to PM0, PM1, PM2, 
TB2SC, INVC0, INVC1 
registers
  0 : Write protected
  1 : Write enabled
Enable write to PD7, PD9, S3C, 
S4C, S5C, S6C registers 

(2)

  0 : Write protected
  1 : Write enabled 

(1)

Reserved Bit

Set to "0"

RW

-

-

(b5-b3)

-

(b7-b6)

Nothing is assigned. When write, set to "0".  
When read, their contents are indeterminate. 

b7

b6

b5

b4

b3

b2

b1

b0

Protect Register

Symbol

Address

 

After Reset

 

PRCR

000Ah

XX000000b

Bit Name

Bit Symbol

Function

NOTES:

1. The PRC2 bit is set to "0" by writing to any address after setting it to "1". Other bits are not set to "0" by writing 

to any address, and must therefore be set in a program.

2. The S5C and S6C registers are only in the 128-pin version. 

0   0  0