236CHAPTER 9 8-BIT TIMER/EVENT COUNTERS 1 AND 29.4 8-Bit Timer/Event Counters 1 and 2 Operations9.4.1 8-bit timer/event counter mode(1) Interval timer operationsThe 8-bit timer/event counters 1 and 2 operate as interval timers which generate interrupt requestsrepeatedly at intervals of the count value preset to 8-bit compare registers 10 and 20 (CR10 and CR20).When the count values of the 8-bit timer registers 1 and 2 (TM1 and TM2) match the values set to CR10and CR20, counting continues with the TM1 and TM2 values cleared to 0 and the interrupt request signals(INTTM1 and INTTM2) are generated.Count clock of the TM1 can be selected with bits 0 to 3 (TCL10 to TCL13) of the timer clock select register1 (TCL1). Count clock of the TM2 can be selected with bits 4 to 7 (TCL14 to TCL17) of the timer clock selectregister 1 (TCL1).For the operation in the case the value of the compare register is changed during the timer count operation,refer to 9.5 8-Bit Timer/Event Counters 1 and 2 Precautions (3).Figure 9-8. Interval Timer Operation TimingRemark Interval time = (N + 1) x t : N = 00H to FFHCount ClockTM1 Count ValueINTTM1CR10TO1Interval Time Interval Time Interval TimeInterrupt Request Acknowledge Interrupt Request AcknowledgeNNNNCount Start Clear Cleart00 01 N 00 01 N 00 01 N
