f OCnxPWM = -----------------------------------
ATmega128
The P W M frequency for the output can be calculated by the following equation:
f clk_I/O
N ? ( 1 + TOP )
The N variable represents the prescaler divider (1, 8, 64, 256, or 1024).
The extreme values for the OCRnx Register represents special cases when generating a P W M
waveform output in the fast P W M mode. If the OCRnx is set equal to BOTTOM (0x0000) the out-
put will be a narrow spike for each TOP+1 timer clock cycle. Setting the OCRnx equal to TOP
will result in a constant high or low output (depending on the polarity of the output set by the
COMnx1:0 bits.)
A frequency (with 50% duty cycle) waveform output in fast P W M mode can be achieved by set-
ting OCnA to toggle its logical level on each compare match (COMnA1:0 = 1). This applies only
if OCRnA is used to define the TOP value ( W GMn3:0 = 15). The waveform generated will have
a maximum frequency of f OC n A = f clk_I/O /2 when OCRnA is set to zero (0x0000). This feature is
similar to the OCnA toggle in CTC mode, except the double buffer feature of the output compare
unit is enabled in the fast P W M mode.
Phase Correct PWM
Mode
The phase correct Pulse Width Modulation or phase correct P W M mode ( W GMn3:0 = 1, 2, 3,
10, or 11) provides a high resolution phase correct P W M waveform generation option. The
R PCPWM = ----------------------------------
phase correct P W M mode is, like the phase and frequency correct P W M mode, based on a dual-
slope operation. The counter counts repeatedly from BOTTOM (0x0000) to TOP and then from
TOP to BOTTOM. In non-inverting compare output mode, the output compare (OCnx) is cleared
on the compare match between TCNTn and OCRnx while counting up, and set on the compare
match while downcounting. In inverting Output Compare mode, the operation is inverted. The
dual-slope operation has lower maximum operation frequency than single slope operation. How-
ever, due to the symmetric feature of the dual-slope P W M modes, these modes are preferred for
motor control applications.
The P W M resolution for the phase correct P W M mode can be fixed to 8-bit, 9-bit, or 10-bit, or
defined by either ICRn or OCRnA. The minimum resolution allowed is 2 bit (ICRn or OCRnA set
to 0x0003), and the maximum resolution is 16 bit (ICRn or OCRnA set to MAX). The P W M reso-
lution in bits can be calculated by using the following equation:
log ( 2 )
In phase correct P W M mode the counter is incremented until the counter value matches either
one of the fixed values 0x00FF, 0x01FF, or 0x03FF ( W GMn3:0 = 1, 2, or 3), the value in ICRn
( W GMn3:0 = 10), or the value in OCRnA ( W GMn3:0 = 11). The counter has then reached the
TOP and changes the count direction. The TCNTn value will be equal to TOP for one timer clock
cycle. The timing diagram for the phase correct P W M mode is shown on Figure 53 . The figure
shows phase correct P W M mode when OCRnA or ICRn is used to define TOP. The TCNTn
value is in the timing diagram shown as a histogram for illustrating the dual-slope operation. The
diagram includes non-inverted and inverted P W M outputs. The small horizontal line marks on
the TCNTn slopes represent compare matches between OCRnx and TCNTn. The OCnx inter-
rupt flag will be set when a compare match occurs.
126
2467X–AVR–06/11
相关PDF资料
ATMEGA64RZAPV-10AU BUNDLE ATMEGA644P/AT86RF230 TQFP
ATP101-TL-H MOSFET P-CH 30V 25A ATPAK
ATP102-TL-H MOSFET P-CH 30V 40A ATPAK
ATP103-TL-H MOSFET P-CH 30V 55A ATPAK
ATP104-TL-H MOSFET P-CH 30V 75A ATPAK
ATP106-TL-H MOSFET P-CH 40V 30A ATPAK
ATP107-TL-H MOSFET P-CH 40V 50A ATPAK
ATP108-TL-H MOSFET P-CH 40V 70A ATPAK
相关代理商/技术参数
ATMEGA128RFA1-ZUR SL514 制造商:Atmel Corporation 功能描述:
ATMEGA128RFA1-ZUR00 制造商:Atmel Corporation 功能描述:2.4GHZ 802.15.4 128K SOC REVF 制造商:Atmel Corporation 功能描述:2.4GHZ 802.15.4 128K SOC REVF T&R - Bulk 制造商:Atmel from Components Direct 功能描述:ATMEL ATMEGA128RFA1-ZUR00 MICROCONTROLLERS (MCU) 制造商:Atmel 功能描述:Atmel ATMEGA128RFA1-ZUR00 Microcontrollers (MCU) 制造商:Atmel Corporation 功能描述:MCU AVR 2.4GHZ 128K FLASH 64VQFN 制造商:Atmel Corporation 功能描述:2.4GHZ 802.15.4 128K SOC Revision F 制造商:Atmel 功能描述:2.4GHZ 802.15.4 128K SOC REVF
ATMEGA128RFR2-ZF 功能描述:IC RF TXRX+MCU 802.15.4 64-VFQFN 制造商:microchip technology 系列:- 包装:托盘 零件状态:在售 类型:TxRx + MCU 射频系列/标准:802.15.4 协议:Zigbee? 调制:DSSS, O-QPSK 频率:2.4GHz 数据速率(最大值):2Mbps 功率 - 输出:3.5dBm 灵敏度:-100dBm 存储容量:128kB 闪存,4kB EEPROM,16kB SRAM 串行接口:I2C,JTAG,SPI,USART GPIO:35 电压 - 电源:1.8 V ~ 3.6 V 电流 - 接收:5mA ~ 12.5mA 电流 - 传输:8mA ~ 14.5mA 工作温度:-40°C ~ 125°C 封装/外壳:64-VFQFN 裸露焊盘 标准包装:260
ATMEGA128RFR2-ZU 制造商:Atmel Corporation 功能描述:2.4GHZ 802.15.4 128K SOC IND 85C - Bulk
ATMEGA128RFR2-ZUR 制造商:Atmel Corporation 功能描述:2.4GHZ 802.15.4 128K SOC 85C T&R - Tape and Reel
ATMEGA128RZAV-8AU 功能描述:射频微控制器 - MCU AVR Z-Link Bundle RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:Si100x 数据总线宽度:8 bit 最大时钟频率:24 MHz 程序存储器大小:64 KB 数据 RAM 大小:4 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 + 85 C 封装 / 箱体:LGA-42 安装风格:SMD/SMT 封装:Tube
ATMEGA128RZAV-8MU 功能描述:射频微控制器 - MCU AVR Z-Link Bundle RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:Si100x 数据总线宽度:8 bit 最大时钟频率:24 MHz 程序存储器大小:64 KB 数据 RAM 大小:4 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 + 85 C 封装 / 箱体:LGA-42 安装风格:SMD/SMT 封装:Tube