Om rlx (see, Figure 14-7 – Rainbow Electronics AT89LP214 User Manual
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3538A–MICRO–7/06
AT89LP213/214 [Preliminary]
Figure 14-7. Timer/Counter 1 PWM Mode 1
14.5.3
Mode 2 – 8-bit Frequency Generator
Timer 0 in PWM Mode 2 functions as an 8-bit auto-reload timer, the same as normal Mode 2,
with the exception that the output pin T0 is toggled at every TL0 overflow (see
Timer 1 in PWM Mode 2 is identical to Timer 0. PWM Mode 2 can be used to output a square
wave of varying frequency. THx acts as an 8-bit counter. The following formula gives the output
frequency for Timer 0 in PWM Mode 2.
Figure 14-8. Timer/Counter 1 PWM Mode 2
Note:
{RH0 & RL0}/{RH1 & RL1} are not required by Timer 0/Timer 1 during PWM Mode 2 and may be
used as temporary storage registers.
OSC
TR1
GATE
INT1 Pin
TL1
(8 Bits)
Control
TH1
(8 Bits)
OCR1
RH1
(8 Bits)
=
T1
RL1
(8 Bits)
÷TPS
Mode 2:
f
out
Oscillator Frequency
2
256
TH
0
–
(
)
×
-------------------------------------------------------
1
TPS
1
+
--------------------
×
=
OSC
TR1
GATE
INT1 Pin
TL1
(8 Bits)
Control
T1
TH1
(8 Bits)
÷TPS