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CHAPTER 14 SERIAL INTERFACE (SIO3)
Preliminary User’s Manual U16035EJ1V0UM
14.3 Registers to Control Serial Interface
The serial interface (SIO3n) is controlled by serial operation mode register 3n (CSIM3n).
(1) Serial operation mode register 30 (CSIM30)
This register is used to enable or disable SIO30’s serial clock, operation modes, and specific operations.
CSIM30 is set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM30 to 00H.
Caution
In 3-wire serial I/O mode, set the port mode register (PMXX) as follows. Set the output latch of the port
set to output mode (PMXX = 0) to 0.
<When SIO30 is used>
During serial clock output
PM22 = 0: Sets P22 (SCK30) to output mode
(master transmission or master reception)
P22 = 0: Sets output latch of P22 to 0
During serial clock input
PM22 = 1: Sets P22 (SCK30) to input mode
(slave transmission or slave reception)
Transmit/receive mode
PM21 = 0: Sets P21 (SO30) to output mode
P21 = 0: Sets output latch of P21 to 0
Receive mode
PM20 = 1: Sets P20 (SI30) to input mode