RL78/G15  CHAPTER 4  PORT FUNCTIONS 
R01UH0959EJ0110    Rev.1.10  Page  117  of 765 
Mar 7, 2023 
Table 4-6.  Concept of Basic Settings 
Output Function of Used Pin  Output Settings of Unused Alternate Function 
  Output Function for Port  Output Function for SAU 
Output Function for other 
than SAU 
Output function for port  —  Output: High (1)  Output: Low (0) 
Output function for SAU  High (1)  —  Output: Low (0) 
Output function for other 
than SAU 
Low (0)  don’t care  Output:Low (0)
Note 1
 
Note 1.  Since more than one output function other than SAU may be assigned to a single pin, the output of an 
unused alternate function must be set to low level (0). For details on the setting method, see 4.5.2  Register 
settings for alternate function whose output function is not used. 
 
4.5.2  Register settings for alternate function whose output function is not used 
When the output of an alternate function of the pin is not used, the following settings should be made. Note that when the 
peripheral I/O redirection function is the target, the output can be switched to another pin by setting the peripheral I/O 
redirection registers 0 to 3 (PIOR0 to PIOR3). This allows usage of the port function or other alternate function assigned 
to the target pin. 
(1)  SOp = 1, TxDq = 1 (settings when the serial output (SOp/TxDq) of SAU is not used) 
When the serial output (SOp/TxDq) is not used, such as, a case in which only the serial input of SAU is used, set the bit 
in serial output enable register 0 (SOE0) which corresponds to the unused output to 0 (output disabled) and set the 
SO0n bit in serial output register 0 (SO0) to 1 (high). These are the same settings as the initial state. 
(2)  SCKp = 1, SDAr = 1, SCLr = 1 (settings when channel n in SAU is not used) 
When SAU is not used, set bit n (SE0n) in serial channel enable status register 0 (SE0) to 0 (operation stopped state), 
set the bit in serial output enable register 0 (SOE0) which corresponds to the unused output to 0 (output disabled), and 
set the SO0n and CKO0n bits in serial output register 0 (SO0) to 1 (high). These are the same settings as the initial 
state. 
(3)  TO0n = 0 (settings when the output of channel n in TAU is not used) 
When the TO0n output of TAU is not used, set the bit in timer output enable register 0 (TOE0) which corresponds to the 
unused output to 0 (output disabled) and set the bit in timer output register 0 (TO0) to 0 (low). These are the same 
settings as the initial state. 
(4)  SDAA0 = 0, SCLA0 = 0 (settings when IICA is not used) 
When IICA is not used, set the IICE0 bit in IICA control register 00 (IICCTL00) to 0 (operation stopped). This is the same 
setting as the initial state.