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(4) 8-bit PWM (Pulse width modulation) output mode
This mode is only valid for TMRA0. In this mode, a PWM pulse with the maximum
resolution of 8 bits can be output.
When TMRA0 is used the PWM pulse is output on the TA1OUT pin. TMRA1 can
also be used as an 8-bit timer.
The timer output is inverted when the up counter (UC0) matches the value set in
the timer register TA0REG or when 2
specified by TA01MOD<PWM01:00>). The up counter UC0 is cleared when 2
overflow occurs.
The following conditions must be satisfied before this PWM mode can be used.
Value set in TA0REG < Value set for 2
Value set in TA0REG ≠ 0
TA0REG and
UC0 match
n
2
overflow
(INTTA0 interrupt)
TA1OUT
Figure 3.7.16 8-Bit PWM Waveforms
Figure 3.7.17 shows a block diagram representing this mode.
TA0IN
φT1
Selector
φT4
φT16
TA01MOD<TA0CLK1:0>
Selector
Shift trigger
TA0REG-WR
TA01RUN<TA0RDE>
Figure 3.7.17 Block Diagram of 8-Bit PWM Mode
counter overflow occurs (n = 6, 7 or 8 as
n
t
PWM
(PWM cycle)
TA01RUN<TA0RUN>
8-bit up counter
Clear
(UC0)
n
2
overflow
control
Overflow
Comparator
TA0REG
Register buffer
Internal data bus
91C824-109
counter overflow
n
TA1OUT
TAFF1
Invert
TA01MOD
<PWM01:00>
TMP91C824
counter
n
TA1FFCR
<TA1FFIE>
INTTA0
2008-02-20
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