Datasheet

RL78/L12 CHAPTER 12 SERIAL ARRAY UNIT
R01UH0330EJ0200 Rev.2.00 408
Dec 13, 2013
12.4 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.
12.4.1 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, set bit 2 (SAU0EN) to 0.
Figure 12-21. Peripheral Enable Register 0 (PER0) Setting When Stopping the Operation by Units
Cautions 1. If SAU0EN = 0, writing to a control register of serial array unit m is ignored, and, even if the
register is read, only the default value is read
Note that this does not apply to the following registers.
• Input switch control register (ISC)
• Noise filter enable register 0 (NFEN0)
• Serial standby control register 0 (SSC0)
• Port input mode register 1 (PIM1)
• Port output mode register 1 (POM1)
• LCD port function registers 0, 3 (PFSEG0, PFSEG3)
• Port mode register 1 (PM1)
• Port register 1 (P1)
2. Be sure to clear bits to 6, 3, 1 to “0”.
Remark : Setting disabled (set to the initial value)
×: 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
(a) Peripheral enable register 0 (PER0) … Set only the bit of SAUm to be stopped to 0.
7 6 5 4 3 2 1 0
PER0
RTCEN
×
0
ADCEN
×
IICA0EN
Note 2
×
0
SAU0EN
0/1 0
TAU 0 EN
×
Control of SAU input clock
0: Stops supply of input clock
1: Su
pp
lies in
p
ut clock