參數(shù)資料
型號(hào): ST72F321J7TA
廠商: 意法半導(dǎo)體
英文描述: 64/44-PIN 8-BIT MCU WITH 32 TO 60K FLASH/ROM, ADC, FIVE TIMERS, SPI, SCI, I2C INTERFACE
中文描述: 64/44-PIN 8位微控制器32點(diǎn),至60,000閃存/ ROM,ADC的,5個(gè)定時(shí)器,SPI和SCI的I2C接口
文件頁數(shù): 80/189頁
文件大小: 3090K
代理商: ST72F321J7TA
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ST72321
80/189
16-BIT TIMER
(Cont’d)
10.4.3.6 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.
Pulse Width Modulation mode uses the complete
Output Compare 1 function plus the OC2R regis-
ter, and so this functionality can not be used when
PWM mode is activated.
In PWM mode, double buffering is implemented on
the output compare registers. Any new values writ-
ten in the OC1R and OC2R registers are taken
into account only at the end of the PWM period
(OC2) to avoid spikes on the PWM output pin
(OCMP1).
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 the OC1R register.
– Using the OLVL2 bit, select the level to be ap-
plied to the OCMP1 pin after a successful
comparison with the 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 16
Clock Control Bits
).
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 16 Clock
Control Bits
)
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 53
)
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 to 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 each period and
ICF1 can also generates 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
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ST72F321J7TAE 功能描述:8位微控制器 -MCU 8B MCU RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) 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(fēng)格:SMD/SMT
ST72F321J7TCE 制造商:STMicroelectronics 功能描述:
ST72F321J9T3 功能描述:8位微控制器 -MCU Flash 60K SPI/I2C/SC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) 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(fēng)格:SMD/SMT
ST72F321J9T3TR 制造商:STMicroelectronics 功能描述:
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