? 256 – PCA0CPHn ?
C8051F380/1/2/3/4/5/6/7/C
27.3.5. 8-bit Pulse Width Modulator Mode
The duty cycle of the PWM output signal in 8-bit PWM mode is varied using the module's PCA0CPLn cap-
ture/compare register. When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the
value in PCA0CPLn, the output on the CEXn pin will be set. When the count value in PCA0L overflows, the
CEXn output will be reset (see Figure 27.8). Also, when the counter/timer low byte (PCA0L) overflows from
0xFF to 0x00, PCA0CPLn is reloaded automatically with the value stored in the module’s capture/compare
high byte (PCA0CPHn) without software intervention. Setting the ECOMn and PWMn bits in the
PCA0CPMn register enables 8-Bit Pulse Width Modulator mode. If the MATn bit is set to 1, the CCFn flag
for the module will be set each time an 8-bit comparator match (rising edge) occurs. The duty cycle for 8-
Bit PWM Mode is given in Equation 27.2.
Important Note About Capture/Compare Registers : When writing a 16-bit value to the PCA0 Cap-
ture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to 0; writing to PCA0CPHn sets ECOMn to 1.
Duty Cycle = -------------------------------------------------------
256
Equation 27.2. 8-Bit PWM Duty Cycle
Using Equation 27.2, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is
0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to 0.
Write to
PCA0CPLn
0
Reset
Write to
ENB
PCA0CPHn
PCA0CPHn
ENB
1
PCA0CPMn
P E C C M T P E
W C A A A O W C
M O P P T G M C
1 M P N n n n F
6 n n n
n
n
PCA0CPLn
COVF
0
0 0 x 0
x
Enable
8-bit
Comparator
match
S
SET
Q
CEXn
Crossbar
Port I/O
R
CLR
Q
PCA Timebase
PCA0L
Overflow
Figure 27.8. PCA 8-Bit PWM Mode Diagram
306
Rev. 1.4
相关PDF资料
C8051F912DK KIT DEV FOR C8051F91X/C8051F90X
C8051F930-TB BOARD TARGET/PROTO W/C8051F930
C8051T610DB24 DAUGHTER BOARD T610 24QFN SOCKET
C8051T630DB20 BOARD SOCKET DAUGHTER 20-QFN
CAN-100 BOARD EVAL RS232 100QFP
CANADAPT28 KIT ADAPTER CANDEMOBOARD 28PLCC
CAT24AA01WI-GT3 IC EEPROM SERIAL 1KB I2C 8SOIC
CAT24AA02WI-G IC EEPROM SERIAL 2KB I2C 8SOIC
相关代理商/技术参数
C8051F381 制造商:SILABS 制造商全称:SILABS 功能描述:USB DRIVER CUSTOMIZATION
C8051F381-GM 功能描述:8位微控制器 -MCU USB-64K-Flash RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
C8051F381-GMR 功能描述:8位微控制器 -MCU USB-Flash-64k-ADC RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
C8051F381-GQ 功能描述:8位微控制器 -MCU USB-64K-Flash RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
C8051F381-GQR 功能描述:8位微控制器 -MCU USB-Flash-64k-ADC RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
C8051F382 制造商:SILABS 制造商全称:SILABS 功能描述:USB DRIVER CUSTOMIZATION
C8051F382-GQ 功能描述:8位微控制器 -MCU USB-Flash-32k-ADC RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
C8051F382-GQR 功能描述:8位微控制器 -MCU USB-Flash-32k-ADC RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT