8-Bit Timer/Event Counters 1 And 2 Operations; 8-Bit Timer/Event Counter Mode; Interval Timer Operation Timing - NEC PD78076 User Manual

9.4 8-Bit Timer/Event Counters 1 and 2 Operations

9.4.1 8-bit timer/event counter mode

(1) Interval timer operations
The 8-bit timer/event counters 1 and 2 operate as interval timers which generate interrupt requests
repeatedly 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 CR10
and 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 register
1 (TCL1). Count clock of the TM2 can be selected with bits 4 to 7 (TCL14 to TCL17) of the timer clock select
register 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).
t
Count Clock
TM1 Count Value 00
Count Start
CR10
INTTM1
TO1
Remark Interval time = (N + 1) x t : N = 00H to FFH
236
CHAPTER 9 8-BIT TIMER/EVENT COUNTERS 1 AND 2
Figure 9-8. Interval Timer Operation Timing
01 N 00
Clear
N N
Interrupt Request Acknowledge
Interval Time
01 N 00
Clear
N
Interrupt Request Acknowledge
Interval Time
01 N
N
Interval Time