M16CSLASH62P datasheet(72/349 Pages) MITSUBISHI

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Clock Generation Circuit

Mitsubishi microcomputers

M16C / 62P Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Under

development

Preliminary Specifications Rev.1.0

Specifications in this manual are tentative and subject to change.

System Clock Protective Function

When the main clock is selected for the CPU clock source, this function disables the clock against modifica-

tions in order to prevent the CPU clock from becoming halted by run-away.

If the PM21 bit of PM2 register is set to “1” (clock modification disabled), the following bits are protected

against writes:

• CM02, CM05, and CM07 bits in CM0 register

• CM10, CM11 bits in CM1 register

• CM20 bit in CM2 register

• All bits in PLC0 register

Before the system clock protective function can be used, the following register settings must be made while

the CM05 bit of CM0 register is “0” (main clock oscillating) and CM07 bit is “0” (main clock selected for the

CPU clock source):

(1) Set the PRC1 bit of PRCR register to “1” (enable writes to PM2 register).

(2) Set the PM21 bit of PM2 register to “1” (disable clock modification).

(3) Set the PRC1 bit of PRCR register to “0” (disable writes to PM2 register).

Do not execute the WAIT instruction when the PM21 bit is “1”.

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