429CHAPTER 19 SERIAL INTERFACE CHANNEL 119.4.3 3-wire serial I/O mode operation with automatic transmit/receive functionThis 3-wire serial I/O mode is used for transmission/reception of a maximum of 32-byte data without the use ofsoftware. Once transfer is started, the data prestored in the RAM can be transmitted by the set number of bytes,and data can be received and stored in the RAM by the set number of bytes.Handshake signals (STB and BUSY) are supported by hardware to transmit/receive data continuously. OSD(On Screen Display) LSI and peripheral LSI including LCD controller/driver can be connected without difficulty.(1) Register settingThe 3-wire serial I/O mode with automatic transmit/receive function is set with the serial operating moderegister 1 (CSIM1), the automatic data transmit/receive control register (ADTC) and the automatic datatransmit/receive interval specify register (ADTI).(a) Serial operating mode register 1 (CSIM1)CSIM1 is set with a 1-bit or 8-bit memory manipulation instruction.RESET input sets CSIM1 to 00H.Notes 1. If the external clock input has been selected with CSIM11 set to 0, set bit 1 (BUSY1) andbit 2 (STRB) of the automatic data transmit/receive control register (ADTC) to 0, 0.2. Can be used freely as port function.3. Can be used as P20 (CMOS input/output) when only transmitter is used (set bit 7 (RE) ofADTC to 0).Remark x : Don’t carePMxx : Port mode registerPxx : Port output latchOperationenable6 <5> 4 3 2 1 0<7>SymbolCSIM1 CSIE1 DIR ATE 0 0 0 CSIM11 CSIM10CSIM1101Serial Interface Channel 1 Clock SelectionClock externally input to SCK1 pinNote 18-bit timer register 2 (TM2) outputSCK1(Input)1 Clock specified with bits 4 to 7 of timer clock select register 3 (TCL3)CSIE10CSIM10x01FF68H 00H R/WAddress After Reset R/WCSIM11P20 PM21 P21 PM22 Shift Register 1OperationSerial Clock CounterOperation ControlSI1/P20 PinFunctionSCK1/P22Pin Functionx1010x 0 01 x1Note 2 Note 2 Note 2 Note 2CountoperationSI1Note 3(Input)x x x x x OperationstopClear P20 (CMOSinput/output)P22 (CMOSinput/output)ATE0Serial Interface Channel 1 Operating Mode Selection3-wire serial I/O modeDIR01Start BitMSBLSBSI1 Pin FunctionSI1/P20(Input)SO1 Pin FunctionSO1(CMOS output)xPM20 SO1/P21 PinFunctionSO1 (CMOSoutput)P21 (CMOSinput/output)SCK1(CMOSoutput)1Note 2Note 2Note 3Note 3P221 3-wire serial I/O mode with automatic transmit/receive function
