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RL78/G1A CHAPTER 12 SERIAL ARRAY UNIT
R01UH0305EJ0200 Rev.2.00 432
Jul 04, 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 0, set bit 2 (SAU0EN) to 0.
To stop the operation of serial array unit 1, set bit 3 (SAU1EN) to 0.
Figure 12-22. Peripheral Enable Register 0 (PER0) Setting When Stopping the Operation by Units
Note 32, 48, and 64-pin products only.
Cautions 1. If SAUmEN = 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)
• Port input mode registers 0, 1 (PIM0, PIM1)
• Port output mode registers 0, 1, 5, 7 (POM0, POM1, POM5, POM7)
• Port mode control registers 0, 1, 3, 5, 7 (PMC0, PMC1, PMC3, PMC5, PMC7)
• Port mode registers 0, 1, 3, 5, 7 (PM0, PM1, PM3, PM5, PM7)
• Port registers 0, 1, 3, 5, 7 (P0, P1, P3, P5, P7)
2. Be sure to clear the following bits to 0.
25-pin products: bits 1, 3, 6
32, 48, 64-pin products: bits 1, 6
Remarks 1. ×: 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
2. m: Unit number (m = 0, 1)
(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
×
SAU1EN
Note
0/1
SAU0EN
0/1
0
×
TAU 0 EN
×
Control of SAUm input clock
0: Stops supply of input clock
1: Su
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