參數資料
型號: ST72T121J4B6
元件分類: 8位微控制器
英文描述: 8-bit Microcontroller with 2/4/8K Bytes In-System Programmable Flash
中文描述: 8位微控制器與2/4/8K字節(jié)在系統可編程閃存
文件頁數: 44/93頁
文件大?。?/td> 915K
代理商: ST72T121J4B6
44/93
ST72E121 ST72T121
16-BIT TIMER
(Cont’d)
5.3.3.6 Pulse Width Modulation Mode
Pulse Width Modulation (PWM) mode enables the
generation of a signal with a frequency and pulse
length determined by the value of the OC1R and
OC2R registers.
The Pulse Width Modulation mode uses the com-
plete Output Compare 1 function plus the OC2R
register, and so these functions cannot be used
when the PWM mode is activated.
Procedure
To use Pulse Width Modulation mode:
1. Load the OC2R register with the value corre-
sponding to the period of the signal using the
formula in the opposite column.
2. Load the OC1R register with the value corre-
sponding to the period of the pulse if OLVL1=0
and OLVL2=1, using the formula in the oppo-
site column.
3. Select the following in the CR1 register:
– Using the OLVL1 bit, select the level to be ap-
plied to the OCMP1 pin after a successful
comparison with OC1R register.
– Using the OLVL2 bit, select the level to be ap-
plied to the OCMP1 pin after a successful
comparison with OC2R register.
4. Select the following in the CR2 register:
– Set OC1E bit: the OCMP1 pin is then dedicat-
ed to the output compare 1 function.
– Set the PWM bit.
– Select the timer clock (CC[1:0]) (see
Table
14
).
If OLVL1=1 and OLVL2=0, the length of the posi-
tive pulse is the difference between the OC2R and
OC1R registers.
If OLVL1=OLVL2 a continuous signal will be seen
on the OCMP1 pin.
The OC
i
R register value required for a specific tim-
ing application can be calculated using the follow-
ing formula:
Where:
t
f
CPU
PRESC
= Timer prescaler factor (2, 4 or 8 depend-
ing on CC[1:0] bits, see
Table 14
)
If the timer clock is an external clock the formula is:
= Signal or pulse period (in seconds)
= CPU clock frequency (in hertz)
Where:
t
f
EXT
= Signal or pulse period (in seconds)
= External timer clock frequency (in hertz)
The Output Compare 2 event causes the counter
to be initialized to FFFCh (See
Figure 31
)
Notes:
1. After a write instruction to the OC
i
HR register,
the output compare function is inhibited until the
OC
i
LR register is also written.
2. The OCF1 and OCF2 bits cannot be set by
hardware in PWM mode, therefore the Output
Compare interrupt is inhibited.
3. The ICF1 bit is set by hardware when the coun-
ter reaches the OC2R value and can produce a
timer interrupt if the ICIE bit is set and the I bit is
cleared.
4. In PWM mode the ICAP1 pin can not be used
to perform input capture because it is discon-
nected from the timer. The ICAP2 pin can be
used to perform input capture (ICF2 can be set
and IC2R can be loaded) but the user must
take care that the counter is reset after each
period and ICF1 can also generate an interrupt
if ICIE is set.
5. When the Pulse Width Modulation (PWM) and
One Pulse mode (OPM) bits are both set, the
PWM mode is the only active one.
Counter
= OC1R
OCMP1 = OLVL2
Counter is reset
to FFFCh
Counter
= OC2R
OCMP1 = OLVL1
When
When
Pulse Width Modulation cycle
ICF1 bit is set
OC
i
R Value =
t
*
f
CPU
PRESC
- 5
OC
i
R =
t
*
f
EXT
-5
44
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ST72T121J4T6 功能描述:8位微控制器 -MCU OTP EPROM 16K SPI/SC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT
ST72T121J4T6S 制造商:STMicroelectronics 功能描述:
ST72T141K2B6 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 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT
ST72T141K2M6 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 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT
ST72T212G2B6 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 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風格:SMD/SMT