CHAPTER 6 16-BIT TIMER/EVENT COUNTER 00User’s Manual U16227EJ2V0UD 1576.5 Cautions for 16-Bit Timer/Event Counter 00(1) Timer start errorsAn error of up to one clock may occur in the time required for a match signal to be generated after timer start.This is because 16-bit timer counter 00 (TM00) is started asynchronously to the count clock.Figure 6-35. Start Timing of 16-Bit Timer Counter 00 (TM00)TM00 count value 0000H 0001H 0002H 0004HCount clockTimer start0003H(2) 16-bit timer capture/compare register setting (in the mode in which clear & start occurs on matchbetween TM00 and CR000)Set 16-bit timer capture/compare registers 000 and 010 (CR000 and CR010) to other than 0000H. This means a1-pulse count operation cannot be performed when 16-bit timer/event counter 00 is used as an event counter.(3) Capture register data retentionThe values of 16-bit timer capture/compare registers 000 and 010 (CR000 and CR010) are not guaranteed after16-bit timer/event counter 00 has been stopped.(4) Valid edge settingSet the valid edge of the TI000 pin after setting bits 2 and 3 (TMC002 and TMC003) of 16-bit timer mode controlregister 00 (TMC00) to 0, 0, respectively, and then stopping timer operation. The valid edge is set using bits 4and 5 (ES000 and ES001) of prescaler mode register 00 (PRM00).(5) Re-triggering one-shot pulse(a) One-shot pulse output by softwareWhen a one-shot pulse is output, do not set the OSPT00 bit to 1. Do not output the one-shot pulse againuntil INTTM000, which occurs upon a match with the CR000 register, or INTTM010, which occurs upon amatch with the CR010 register, occurs.(b) One-shot pulse output with external triggerIf the external trigger occurs again while a one-shot pulse is output, it is ignored.(c) One-shot pulse output functionWhen using the one-shot pulse output of 16-bit timer/event counter 00 with a software trigger, do not changethe level of the TI000 pin or its alternate-function port pin.Because the external trigger is valid even in this case, the timer is cleared and started even at the level of theTI000 pin or its alternate-function port pin, resulting in the output of a pulse at an undesired timing.
