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Chapter 19 Timebase Timer
7.Q & A
7. Q & A
7.1 What are the types of interval time used in the timebase timer (and the timebase
counter used by the timebase timer) and how to select them?
There are eight types of interval time, and they are set using the interval selection bit (TBCR.TBC[2:0]).
F: This is the base clock. (Refer to “Chapter 13 Clock Control (Page No.189)”.)
7.2 What Is the count clock of the timebase counter?
The count clock is a base clock. Refer to “Chapter 13 Clock Control (Page No.189)”.
7.3 How to operate the timebase timer?
The timebase timer is always operating. (Setting is unnecessary.)
However, to use interval interrupt, interrupt setting is required.
7.4 How is the timebase timer (=timebase counter) operation stopped?
It cannot be stopped.
7.5 How is the timebase counter (=timebase timer) cleared?
If you write {A5
H
} and {5A
H
} successively in the timebase counter clear register CTBR, the timebase counter
is cleared immediately after {5A
H
}. (All bits are “0”.)
However, if the timebase counter is cleared, the watchdog timer is affected. (Refer to “8. Caution (Page
No.271)”)
7.6 How about the interrupt-associated registers?
Setting timebase timer’s interrupt vector and interrupt level
The relationship between the interrupt level and vector is shown in the following table.
Refer to “Chapter 24 Interrupt Control (Page No.311)” for more information on the interrupt level and interrupt
vector.
The interrupt request flag (TBCR.TBIF) cannot automatically be cleared. As a result, clear it by the software
before returning from an interrupt service. (Write “0” in the interrupt request flag (TBIF).)
Timebase timer
Interval time
Interval selection bit
(TBC[2:0])
Example Interval time
FΦ =2MHz FΦ = 32MHz
FΦ =
32.768kHz
How to select Φ × 2
11
?
Set the value to “000” 1.024ms
64
µs
62.5ms
How to select Φ × 2
12
?
Set the value to “001” 2.048ms
128
µs
125ms
How to select Φ × 2
13
?
Set the value to “010” 4.096ms
256
µs
256ms
How to select Φ × 2
22
?
Set the value to “011” 2.097s 131ms 128s
How to select Φ × 2
23
?
Set the value to “100” 4.194s 262ms 256s
How to select Φ × 2
24
?
Set the value to “101” 8.388s 524ms 512s
How to select Φ × 2
25
?
Set the value to “110” 16.77s 1.04s 1024s
How to select Φ × 2
26
?
Set the value to “111” 33.55s 2.09s 2048s
Interrupt vector (default) Interrupt level setting bit (ICR[4:0])
#140
Address: 0FFDCCh
Interrupt level register (ICR62)
Address: 047Eh
