AT89LP6440 Atmel Corporation, AT89LP6440 Datasheet - Page 59

• Manufacturer Part Number: AT89LP6440
• Manufacturer: Atmel Corporation

Specifications of AT89LP6440

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 38
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 4.25
• Eeprom (bytes): 8192
• Self Program Memory: IAP
• Operating Voltage (vcc): 2.4 to 3.6
• Timers: 3
• Isp: SPI/OCD
• Watchdog: Yes

11.5.4
3706C–MICRO–2/11
Mode 3 – Split 8-bit PWM
Timer 1 in PWM Mode 3 simply holds its count. The effect is the same as setting TR1 = 0.
Timer 0 in PWM Mode 3 establishes TL0 and TH0 as two separate PWM counters in a manner
similar to normal Mode 3. PWM Mode 3 on Timer 0 is shown in
Prescaler is available to change the output frequency during PWM Mode 3. TL0 can use the
Timer 0 control bits: GATE, TR0, INT0, PWM0EN and TF0. TH0 is locked into a timer function
and uses TR1, PWM1EN and TF1. RL0 provides the duty cycle for TL0 and RH0 provides the
duty cycle for TH0.
PWM Mode 3 is for applications requiring a single PWM channel and two timers, or two PWM
channels and an extra timer or counter. With Timer 0 in PWM Mode 3, the AT89LP3240/6440
can appear to have four Timer/Counters. When Timer 0 is in PWM Mode 3, Timer 1 can be
turned on and off by switching it out of and into its own Mode 3. In this case, Timer 1 can still be
used by the serial port as a baud rate generator or in any application not requiring an interrupt.
The following formulas give the output frequency and duty cycle for Timer 0 in PWM Mode 3.
Figure 11-10. Timer/Counter 0 PWM Mode 3
INT0 Pin
GATE0
Mode 3:
Mode 3, T1:
Mode 3, T0:
TR0
OSC
OSC
TR1
f
out
÷TPS
÷TPS
Duty Cycle %
Duty Cycle %
=
Oscillator Frequency
------------------------------------------------------ -
Control
256
=
=
100
100
(8 Bits)
(8 Bits)
(8 Bits)
(8 Bits)
OCR0
OCR1
RL0
RH0
TL0
TH0
×
×
RH0
----------- -
RL0
---------- -
256
256
×
=
=
-------------------- -
TPS
AT89LP3240/6440
1
+
Figure
1
11-10. Only the Timer
T0
T1
59