Toshiba H1 SERIES TLCS-900 - Manual (Page 113)

TMP92CM22
2007-02-16 92CM22-111
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.
When set function and count data, TMRA0 and TMRA1 should be stopped.
1. 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 40
μs at f
C
= 40 MHz, set each register
as follows:
MSB LSB
7 6 5 4 3 2 1 0
TA01RUN
← − X X X − − 0 −
Stop TMRA1 and clear it to 0.
TA01MOD
← 0 0 X X 0
1
− −
Select 8-bit timer mode and select
φT1 (=(16/fc)s at f
C
=
40MHz) as the input clock.
TA1REG
← 0
1 1 0 0 1 0 0 Set 40
μs ÷ φT1 = 100 = 64H to TAREG.
INTETA01 ← X 1 0 1 − − − − Enable INTTA1 and set it to Level 5.
TA01RUN
← − X X X − 1
1
−
Start TMRA1 counting.
X
: Don’t care, − : No change
Select the input clock refers to Table 3.7.3.
Table 3.7.3 Selecting Interrupt Interval and the Input Clock Using 8-Bit Timer
Input clock Interrupt Interval (at f
SYS
= 20 MHz)
Resolution
φT1 (8/f
SYS )
φT4 (32/f
SYS
)
φT16 (128/f
SYS )
φT256 (2048/f
SYS
)
0.4
μs to 102.4 μs
1.6
μs to 409.6 μs
6.4
μs to 1.638 ms
102.4 μs to 26.21 ms
0.4
μs
1.6
μs
6.4
μs
102.4 μs
Note: The input clocks for TMRA0 and TMRA1 differ as follows:
TMRA0: Uses TMRA0 input (TA0IN) and can be selected from
φT1, φT4, or φT16.
TMRA1: Matches output of TMRA0 (TA0TRG) and can be selected from
φT1, φT16,
φT256.