M30620FCAFP datasheet(322/615 Pages) RENESAS

322 / 615 page

Mitsubishi microcomputers

M16C / 62A Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Protect

2-5

Figure 2.1.2. Set-up procedure for protect function

(1) Clearing the protect (set to write-enabled state)

Protect register [Address 000A16]

PRCR

Enables writing to system clock control registers 0 and 1 (addresses 000616 and 000716

)

1 : Write-enabled

Enables writing to port P9 direction register (address 03F316) and SI/Oi control register

(i=3,4) (addresses 036216 and 036616)

0 : Write-inhibited

1 : Write-enabled

(3) Setting the protect (set to write-inhibited state)

Protect register [Address 000A16]

PRCR

Enables writing to system clock control registers 0 and 1 (addresses 000616 and 000716

)

0 : Write-inhibited

Enables writing to port P9 direction register (address 03F316) and SI/Oi control register

(i=3,4) (addresses 036216 and 036616)

0 : Write-inhibited

1 : Write-enabled

(4) Clearing the protect (set to write-enabled state)

Protect register [Address 000A16]

PRCR

Enables writing to system clock control registers 0 and 1 (addresses 000616 and 000716

)

0 : Write-inhibited

1 : Write-enabled

Enables writing to port P9 direction register (address 03F316) and SI/Oi control register (

i=3,4) (addresses 036216 and 036616)

1 : Write-enabled

Setting system clock control register i (i = 0, 1)

(2)

Changes in port P9 or changes in SI/Oi control register (i=3,4)

(5)

2.1.3 Precaution for Protect

(1) The write-enable bit of port 9 direction register and SI/Oi control register (i=3,4) goes to “0”

when the next write instruction is executed after write-enabled state is readied. Make

changes in input/output and SI/Oi control register (i=3,4) immediately after the instruction that

sets “1” in the write-enable bit of port P9 direction register and SI/Oi control register

(i=3,4)(avoid causing an interrupt). Also take measures to prevent DMA transfer from being

executed.

M30620FCAFP Datasheet(PDF) 322 Page - Renesas Technology Corp

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