Let's have a look at how to set each related register and bit when entering the Stop Mode.

• Setting an Interrupt for Leaving Stop Mode

Set an interrupt, which is used to place the MCU out of the Stop Mode. Make sure the priority level set for this interrupt is higher than the Processor Interrupt Priority Level (IPL).

• Enabling the Interrupt Enable Flag (I Flag)

Set the Interrupt Enable Flag (I Flag) in the Flag Register (FLG) to 1 in order to enable all maskable interrupts.

• Removing Protection

Set the bit for enabling writes to System Clock Control Registers 0 and 1 that is assigned in the Protect Register (address 0000A) to 1 in order to remove protection from these two registers.

• Setting the System Clock Control Registers 0 and 1

Set the operating clock to be used after returning from the Stop Mode. The contents to be set in these registers differ depending on whether the microcomputer is operated with the Main Clock or Sub Clock after returning from the Stop Mode.

• Turning All Clocks Off

Set the All Clock Stop Control Bit in the system clock control register 1 to 1 in order to turn all clocks stop. This places the MCU into the Stop Mode. The MCU is placed out of the Stop Mode by an interrupt or a hardware reset.