AT89LP51ED2 Atmel Corporation, AT89LP51ED2 Datasheet - Page 105

• Manufacturer Part Number: AT89LP51ED2
• Manufacturer: Atmel Corporation

Specifications of AT89LP51ED2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 42
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 7
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 2.25
• Eeprom (bytes): 4096
• Self Program Memory: API
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 4
• Isp: SPI/OCD/UART
• Watchdog: Yes

15.6
3714A–MICRO–7/11
Pulse Width Modulator Mode
All of the PCA modules can be used as PWM outputs.
The frequency of the output depends on the source for the PCA timer. All of the modules will
have the same frequency of output because they all share the PCA timer. The duty cycle of each
module is independently variable using the modules capture register CCAPnL. When the value
of the PCA CL SFR is less than the value in the modules CCAPnL SFR the output will be low,
when it is equal to or greater than the output will be high. When CL overflows from FFH to 00H,
CCAPnL is reloaded with the value in CCAPnH. This allows updating the PWM without glitches.
The PWM and ECOM bits in the module's CCAPMn register must be set to enable the PWM
mode. The following equations show the resulting frequency and duty cycles of the generated
output:
Figure 15-7. PCA PWM Mode
An example PCA PWM waveform is shown in
Figure 15-8. PCA PWM Waveform
CL = FFH
CL = 00H
CCAPnH
CEXn
CCAPnH
CCAPnL
CPS
CL
AT89LP51RD2/ED2/ID2 Preliminary
Duty Cycle %
=
CCAPMn.6
ECOMn
ECOMn
00B:
+
–
>
=
CCAPMn.1
PWMn
100
f
Figure
out
PWMn = 1, ECOMn = 1
×
=
256 CCAPnL
-------------------------------------- -
f
---------- -
256
15-8.
SYS
Module n
–
Figure 15-7
×
256
-------------------- -
TPS
1
+
1
shows the PWM function.
CEXn
105