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TMP91C824
91C824-104
Example: To generate 1/4-duty 50-kHz pulses (at fc = 16 MHz):
20
µ
s
∗
Clock state
System clock: High frequency (fc)
Clock gear: 1 (fc)
Prescaler clock: f
FPH
Calculate the value which should be set in the timer register.
To obtain a frequency of 50 kHz, the pulse cycle t should be: t = 1/50 kHz = 20
μ
sec
φ
T1 = 0.5
µ
sec (at 16 MHz);
20
µ
sec / 0.5
µ
sec = 40
Therefore set TA1REG to 40 (28H)
The duty is to be set to 1/4: t
×
1/4 = 20
µ
sec
×
1/4 = 5
µ
sec
5
µ
sec / 0.5
µ
sec = 10
Therefore, set TA0REG = 10 = 0AH.
7 6
5
4 3 2
1
0
TA01RUN
←
0
X X
X
–
0
0
0
Stop TMRA0 and TMRA01 and clear it to “0”.
TA01MOD
←
1
0
X
X
X
X
0
1
Set the 8-bit PPG mode, and select
φ
T1 as input clock.
TA0REG
←
0 0
0
0 1 0
1
0
Write
0AH
TA1REG
←
0 0
1
0 1 0
0
0
Write
28H
TA1FFCR
←
X
X X
X
0
1
1
X
Set TA1FF, enabling both inversion and the double buffer.
Writing “10” provides negative logic pulse.
PBCR
←
X –
–
– – –
1
–
PBFC
←
X –
–
– – –
1
X
Set PB1 as the TA1OUT pin.
TA01RUN
←
1
X X
X
–
1
1
1
Start TMRA0 and TMRA01 counting.
(note): X = Don’t care; “
−
” = No change