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3.7.4
Operation in Each Mode
(1) 8-bit timer mode
Both TMRA0 and TMRA1 can be used independently as 8-bit interval timers.
Setting its function or counter data for TMRA0 and TMRA1 after stop these
registers.
a.
Generating interrupts at a fixed interval (using TMRA1)
To generate interrupts at constant intervals using TMRA1 (INTTA1), first stop
TMRA1 then set the operation mode, input clock and a cycle to TA01MOD and
TA1REG register, respectively. Then, enable the interrupt INTTA1 and start
TMRA1 counting.
Example: To generate an INTTA1 interrupt every 10 µseconds at fc = 33 MHz, set
* Clock state
MSB
7
← −
TA01RUN
← 0
TA01MOD
← 0
TA1REG
← −
INTETA01
← −
TA01RUN
X: Don't care, −: No change
Select the input clock using in Table 3.7.2.
Note: The input clocks for TMRA0 and TMRA1 are different from as follows.
TMRA0: TA0IN input, φT1, φT4 or φT16
TMRA1: Match output of TMRA0, φT1, φT16, φT256
each register as follows:
LSB
6
5
4
3
2
1
0
−
−
−
X
X
X
0
0
X
X
1
0
X
X
0
1
0
1
0
0
0
−
−
−
−
1
0
1
−
−
X
X
X
1
1
91C824-102
System clock:
High frequency (fc)
Prescaler clock: f
FPH
Stop TMRA1 and clear it to 0.
Select 8-bit timer mode and select φT1
/fc)s at fc = 33 MHz) as the input clock.
3
((2
Set TA1REG to 10 µs ÷ φT1 (2
3
Enable INTTA1 and set it to level 5.
Start TMRA1 counting.
TMP91C824
/fc)s ≈ 40 = 28H.
2008-02-20
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