参数资料
型号: ST72P621J4T1
厂商: STMICROELECTRONICS
元件分类: 微控制器/微处理器
英文描述: 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO34
封装: PLASTIC, SO-34
文件页数: 75/136页
文件大小: 2475K
代理商: ST72P621J4T1
ST7262
43/136
PWM AUTO-RELOAD TIMER (Cont’d)
10.2.2 Functional Description
Counter
The free running 8-bit counter is fed by the output
of the prescaler, and is incremented on every ris-
ing edge of the clock signal.
It is possible to read or write the contents of the
counter on the fly by reading or writing the Counter
Access register (ARTCAR).
When a counter overflow occurs, the counter is
automatically reloaded with the contents of the
ARTARR register (the prescaler is not affected).
Counter clock and prescaler
The counter clock frequency is given by:
fCOUNTER = fINPUT / 2
CC[2:0]
The timer counter’s input clock (fINPUT) feeds the
7-bit programmable prescaler, which selects one
of the 8 available taps of the prescaler, as defined
by CC[2:0] bits in the Control/Status Register
(ARTCSR). Thus the division factor of the prescal-
er can be set to 2n (where n = 0, 1,..7).
This fINPUT frequency source is selected through
the EXCL bit of the ARTCSR register and can be
either the fCPU or an external input frequency fEXT.
The clock input to the counter is enabled by the
TCE (Timer Counter Enable) bit in the ARTCSR
register. When TCE is reset, the counter is
stopped and the prescaler and counter contents
are frozen. When TCE is set, the counter runs at
the rate of the selected clock source.
Counter and Prescaler Initialization
After RESET, the counter and the prescaler are
cleared and fINPUT = fCPU.
The counter can be initialized by:
– Writing to the ARTARR register and then setting
the FCRL (Force Counter Re-Load) and the TCE
(Timer Counter Enable) bits in the ARTCSR reg-
ister.
– Writing to the ARTCAR counter access register,
In both cases the 7-bit prescaler is also cleared,
whereupon counting will start from a known value.
Direct access to the prescaler is not possible.
Output compare control
The timer compare function is based on four differ-
ent comparisons with the counter (one for each
PWMx output). Each comparison is made be-
tween the counter value and an output compare
register (OCRx) value. This OCRx register can not
be accessed directly, it is loaded from the duty cy-
cle register (PWMDCRx) at each overflow of the
counter.
This double buffering method avoids glitch gener-
ation when changing the duty cycle on the fly.
Figure 32. Output compare control
COUNTER
FDh
FEh
FFh
FDh
FEh
FFh
FDh
FEh
ARTARR=FDh
fCOUNTER
OCRx
PWMDCRx
FDh
FEh
FDh
FEh
FFh
PWMx
相关PDF资料
PDF描述
ST72621J2B1 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDIP20
ST72621J2T1 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO20
ST72P621L4M1 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO34
ST72623F2M1L 8-BIT, MROM, 4 MHz, MICROCONTROLLER, PDSO34
ST7263BK1B/XXX 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDIP32
相关代理商/技术参数
参数描述
ST72T101G1B6 功能描述:8位微控制器 -MCU OTP EPROM 4K SPI 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
ST72T101G1M6 功能描述:8位微控制器 -MCU OTP EPROM 4K SPI 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
ST72T101G2B6 功能描述:8位微控制器 -MCU OTP EPROM 8K SPI 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
ST72T101G2M6 功能描述:8位微控制器 -MCU RO 511-ST72C104G2M6 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
ST72T121J2B6 功能描述:8位微控制器 -MCU OTP EPROM 8K SPI/SCI 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