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CHAPTER 13 16-Bit I/O TIMER
13.5 Explanation of Operation of 16-bit Free-run Timer
After a reset, the 16-bit free-run timer starts incrementing from "0000
H
". The counter
value of the 16-bit free-run timer is the base time of the input capture.
■ Explanation of Operation of 16-bit Free-run Timer
Operation of the 16-bit free-run timer requires the setting shown in Figure 13.5-1 .
Figure 13.5-1 Setting of 16-bit Free-run Timer
[Setting of counter value in 16-bit free-run timer]
• Because the timer operation is enabled (TCCSL:STOP=0) after a reset, the 16-bit free-run timer starts
incrementing from the counter value "0000
H
".
• When setting the counter value of the 16-bit free-run timer, disable the operation of the 16-bit free-run
timer (TCCSL:STOP=1), set the value that starts counting to the timer data register, enable the timer
operation (TCCSL:STOP=0).
[Generation of overflow and interrupt request]
• When overflow ("FFFF
H
" → "0000
H
") occurs in the 16-bit free-run timer, the timer overflow generation
flag is set to "1" (TCCSL:IVF) and starts incrementing from "0000
H
".
• When the timer overflow interrupt request is enabled (TCCSL:IVFE=1), the interrupt request is
occurred.
[Clear factor of counter value and clear timing]
Table 13.5-1 shows the clear factor and clear timing of the 16-bit free-run timer.
0
STOP
−
CLK1 CLK0
CLR
IVF
IVFE
TCDT
TCCSH/TCCSL
bit15 14 13 12 11 10 9 bit8 bit7 654321bit0
0
CLK2
ECKE
−−−−−−−
0
❍
: Used bit
✕
: Undefined bit
0 : Setting to "0"
Counter value of 16-bit free-run timer
❍
❍
❍❍ ❍
❍
✕✕✕
✕
✕✕
✕
Table 13.5-1 Clear Factor of Counter Value and Clear Timing
Clear factor Clear timing
When "1" to timer clear bit of timer control status register (TCCSL:
CLR)
Synchronize with generation of factor
Write "0000
H
" to timer data register during stopping
Synchronize with generation of factor
Reset Synchronize with generation of factor
Timer overflow Synchronize with count timing