AT89LP428-20MU ATMEL [ATMEL Corporation], AT89LP428-20MU Datasheet - Page 48

• Manufacturer Part Number: AT89LP428-20MU
• Description: 8-bit Microcontroller with 4K/8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

11.5.1
11.5.2
48
AT89LP428/828
Mode 0 – 8-bit PWM with 8-bit Logarithmic Prescaler
Mode 1 – 8-bit PWM with 8-bit Linear Prescaler
In Mode 0, TLx acts as a logarithmic prescaler driving 8-bit counter THx (see
PSCx bits in TCONB control the prescaler value. On THx overflow, the duty cycle value in RHx
is transferred to OCRx and the output pin is set high. When the count in THx matches OCRx, the
output pin is cleared low. The following formulas give the output frequency and duty cycle for
Timer 0 in PWM mode 0. Timer 1 in PWM mode 0 is identical to Timer 0.
Figure 11-6. Timer/Counter 1 PWM Mode 0
In Mode 1, TLx provides linear prescaling with an 8-bit auto-reload from RLx (see
page
THx overflow, the duty cycle value in RHx is transferred to OCRx and the output pin is set high.
When the count in THx matches OCRx, the output pin is cleared low. The following formulas
give the output frequency and duty cycle for Timer 0 in PWM mode 1. Timer 1 in PWM mode 1 is
identical to Timer 0.
INT1 Pin
49). On TLx overflow, TLx is loaded with the value of RLx. THx acts as an 8-bit counter. On
GATE
OSC
TR1
Mode 0:
Mode 1:
÷TPS
Control
f
f
OUT
OUT
=
=
Duty Cycle %
Duty Cycle %
Oscillator Frequency
------------------------------------------------------ -
Oscillator Frequency
------------------------------------------------------ -
PSC1
256
256
×
(8 Bits)
×
(
TL1
256 RL0
2
PSC0
=
=
–
100
100
+
1
(8 Bits)
(8 Bits)
OCR1
)
RH1
TH1
×
×
×
RH0
----------- -
×
RH0
----------- -
256
256
-------------------- -
TPS
-------------------- -
TPS
=
1
1
+
+
1
1
Figure
3654A–MICRO–8/09
Figure 11-7 on
11-6). The
T1