TMP91C824
91C824-105
(4) 8-Bit PWM 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 (which is also used as P71).
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
n
−
1 counter overflow occurs (n = 6, 7 or 8 as specified by
TA01MOD<PWM01 to PWM00>). The up-counter UC0 is cleared when 2
n
−
1 counter overflow
occurs.
The following conditions must be satisfied before this PWM mode can be used.
Value set in TA0REG < value set for 2
n
−
1 counter overflow
Value set in TA0REG
≠
0
TA1OUT
2
n
-1
overflow
(INTTA0 interrupt)
t
PWM
(PWM cycle)
TA0REG and
UC0 match
Figure 3.7.15 8-bit PWM waveforms
Figure 3.7.16 shows a block diagram representing this mode.
TA01MOD
<PWM01
∼
PWM0100>
TA1FFCR
<TAFF1IE>
Internal bus
Shift trigger
Cliar
8-bit up counter
(UC 0)
TA01RUN <TA0RUN>
Selector
φ
T1
φ
T4
φ
T16
TAFF1
TA1OUT
Comparator
TA0REG
Register buffer
Selector
TA01RUN<TA0RDE>
Invert
TA0REG-WR
INTTA0
TA01MOD <TA0CLK1:0>
Overflow
2
n
-1
overflow
control
Figure 3.7.16 Block diagram of 8-Bit PWM Mode