Renesas RL78 Series User Manual page 418

16-bit single-chip microcontrollers

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13.4 Operation stop mode

Each serial interface of serial array unit has the operation stop mode.

In this mode, serial communication cannot be executed, thus reducing the power consumption.

In addition, the pin for serial interface can be used as port function pins in this mode.

13.4.1 Stopping the operation by units

The stopping of the operation by units is set by using peripheral enable register 0 (PER0).

The PER0 register is used to enable or disable supplying the clock to the peripheral hardware. Clock supply to a

hardware macro that is not used is stopped in order to reduce the power consumption and noise.

To stop the operation of serial array unit 0, set bit 2 (SAU0EN) to 0.

To stop the operation of serial array unit 1, set bit 3 (SAU1EN) to 0.

Figure 13-22. Peripheral Enable Register 0 (PER0) Setting When Stopping the Operation by Units

(a) Peripheral enable register 0 (PER0) ... Set only the bit of SAUm to be stopped to 0.

If SAUmEN = 0, writing to a control register of serial array unit m is ignored, and, even if the

Note that this does not apply to the following registers.

● Noise filter enable register 0 (NFEN0)

● Port input mode registers 0, 1 (PIM0, PIM1)

● Port output mode registers 0, 1 (POM0, POM1)

● Port mode control register 0 (PMC0)

● Port mode registers 0, 1, 7 (PM0, PM1, PM7)

● Port registers 0, 1, 7 (P0, P1, P7)

2. Be sure to clear the bits 6 and 1 to 0.

×: Bits not used with serial array units (depending on the settings of other peripheral functions)

0/1: Set to 0 or 1 depending on the usage of the user

R01UH0515EJ0120 Rev.1.20

Dec 16, 2016

Control of SAUm input clock

0: Stops supply of input clock

1: Supplies input clock

CHAPTER 13 SERIAL ARRAY UNIT

Rl78/g1d R5f11agg R5f11agh R5f11agj