8-Bit Timer 1 Tm1 Operations; 8-Bit Interval Timer Operation - NEC mPD780852 Series Preliminary User's Manual

7.4 8-Bit Timer 1 TM1 Operations

7.4.1 8-bit interval timer operation

The 8-bit timer 1 operates as an interval timer which generates interrupt requests repeatedly at intervals of the
count value preset to 8-bit compare register 1 (CR1).
When the count values of the 8-bit counter 1 (TM1) match the values set to CR1, counting continues with the TM1
values cleared to 0 and the interrupt request signal (INTTM1) is generated.
Count clock of the TM1 can be selected with bits 0 to 2 (TCL10 to TCL12) of the timer clock select register 1 (TCL1).
[Setting]
<1> Set the registers.
• TCL1: Select count clock.
• CR1: Compare value
<2> After TCE1 = 1 is set, count operation starts.
<3> If the values of TM1 and CR1 match, the INTTM1 is generated and TM1 is cleared to 00H.
<4> INTTM1 generates repeatedly at the same interval. Set TCE1 to 0 to stop count operation.
t
Count clock
TM1 count value 00H
Start count
CR1
TCE1
INTTM1
Note
TM1 interval time
Remark Interval time = (N + 1) × t: N = 00H to FFH
CHAPTER 7 8-BIT TIMER 1 TM1
Figure 7-4. Interval Timer Operation Timings (1/3)
(a) Basic operation
01H N 00H
Clear
N N
Interrupt received
Interval time
Preliminary User's Manual U14581EJ3V0UM00
01H N 00H
Clear
N
Interrupt received
Interval time
01H N
N
Interval time
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