CHAPTER 11 CLOCK OUTPUT/BUZZER OUTPUT CONTROLLERUser’s Manual U16899EJ2V0UD 245(2) Port mode register 14 (PM14)This register sets port 14 input/output in 1-bit units.When using the P140/INTP6/PCL pin for clock output and the P141/INTP7/BUZ pin for buzzer output, setPM140, PM141 and the output latch of P140, P141 to 0.PM14 is set by a 1-bit or 8-bit memory manipulation instruction.RESET input sets PM14 to FFH.Figure 11-3. Format of Port Mode Register 14 (PM14)Address: FF2EH After reset: FFH R/WSymbol 7 6 5 4 3 2 1 0PM14 1 1 1 1 1 1 PM141 PM140PM14n P14n pin I/O mode selection (n = 0, 1)0 Output mode (output buffer on)1 Input mode (output buffer off)11.4 Clock Output/Buzzer Output Controller Operations11.4.1 Clock output operationThe clock pulse is output as the following procedure.<1> Select the clock pulse output frequency with bits 0 to 3 (CCS0 to CCS3) of the clock output selection register(CKS) (clock pulse output in disabled status).<2> Set bit 4 (CLOE) of CKS to 1 to enable clock output.Remark The clock output controller is designed not to output pulses with a small width during outputenable/disable switching of the clock output. As shown in Figure 11-4, be sure to start output from thelow period of the clock (marked with * in the figure). When stopping output, do so after securing highlevel of the clock.Figure 11-4. Remote Control Output Application ExampleCLOEClock output* *11.4.2 Operation as buzzer outputThe buzzer frequency is output as the following procedure.<1> Select the buzzer output frequency with bits 5 and 6 (BCS0, BCS1) of the clock output selection register(CKS) (buzzer output in disabled status).<2> Set bit 7 (BZOE) of CKS to 1 to enable buzzer output.
