参数资料
型号: ST72774S9T1/XXX
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, PQFP44
封装: TQFP-44
文件页数: 87/144页
文件大小: 1280K
代理商: ST72774S9T1/XXX
ST72774/ST727754/ST72734
47/144
16-BIT TIMER (Cont’d)
4.3.3.4 Output Compare
In this section, the index,
i, may be 1 or 2.
This function can be used to control an output
waveform or indicating when a period of time has
elapsed.
When a match is found between the Output
Compare register and the free running counter, the
output compare function:
– Assigns pins with a programmable value if the
OCIE bit is set
– Sets a flag in the status register
– Generates an interrupt if enabled
Two 16-bit registers Output Compare Register 1
(OC1R) and Output Compare Register 2 (OC2R)
contain the value to be compared to the free
running counter each timer clock cycle.
These registers are readable and writable and are
not affected by the timer hardware. A reset event
changes the OCiR value to 8000h.
Timing resolution is one count of the free running
counter: (
fCPU/(CC1.CC0)).
Procedure
To use the output compare function, select the
following in the CR2 register:
– Set the OC
iE bit if an output is needed then the
OCMP
i pin is dedicated to the output compare i
function.
– Select the timer clock (CC1-CC0) (see Table 15
Clock Control Bits).
And select the following in the CR1 register:
– Select the OLVL
i bit to applied to the OCMPi pins
after the match occurs.
– Set the OCIE bit to generate an interrupt if it is
needed.
When match is found:
– OCF
i bit is set.
– The OCMP
i pin takes OLVLi bit value (OCMPi
pin latch is forced low during reset and stays low
until valid compares change it to a high level).
– A timer interrupt is generated if the OCIE bit is
set in the CR2 register and the I bit is cleared in
the CC register (CC).
Clearing the output compare interrupt request is
done by:
3. Reading the SR register while the OCF
i bit is
set.
4. An access (read or write) to the OC
iLR register.
Note: After a processor write cycle to the OC
iHR register,
the output compare function is inhibited until the
OC
iLR register is also written.
If the OC
iE bit is not set, the OCMPi pin is a
general I/O port and the OLVL
i bit will not appear
when match is found but an interrupt could be
generated if the OCIE bit is set.
The value in the 16-bit OCiR register and the OLV
i
bit should be changed after each successful
comparison in order to control an output waveform
or establish a new elapsed timeout.
The OCiR register value required for a specific
timing application can be calculated using the
following formula:
Where:
t
= Desired output compare period (in
seconds)
fCPU
= Internal clock frequency
CC1-CC0 = Timer clock prescaler
The following procedure is recommended to
prevent the OCF
i bit from being set between the
time it is read and the write to the OCiR register:
– Write to the OC
iHR register (further compares
are inhibited).
– Read the SR register (first step of the clearance
of the OCF
i bit, which may be already set).
– Write to the OC
iLR register (enables the output
compare function and clears the OCF
i bit).
MS Byte
LS Byte
OC
iROCiHR
OC
iLR
OCiR =
t * fCPU
(CC1.CC0)
相关PDF资料
PDF描述
ST72E734J6D0 8-BIT, UVPROM, 8 MHz, MICROCONTROLLER, CDIP42
ST72T774S9T1 8-BIT, OTPROM, 8 MHz, MICROCONTROLLER, PQFP44
ST7294C6B6 8-BIT, MROM, 4 MHz, MICROCONTROLLER, PDIP28
ST72T94C6M6 8-BIT, OTPROM, MICROCONTROLLER, PDSO28
ST72C171K2B6 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PDIP32
相关代理商/技术参数
参数描述
ST727X4-EMU2B 制造商:STMicroelectronics 功能描述:REALTIME EMULATOR BOARD - Bulk
ST727X4-EPB/US 制造商:STMicroelectronics 功能描述:PROGRAMMER - Bulk
ST-7-28 功能描述:XFRMR PWR 115V 14VAC 2.6A RoHS:是 类别:变压器 >> 功率 系列:ST 标准包装:1 系列:260 类型:标准 最大功率:65 VA 主线圈:双 副线圈:三路,中心抽头 在某电流时的串联输出电压:500 VAC @ 85mA,5 VAC @ 2A,6.3 VAC @ 2A 在某电流时的并联输出电压:- 安装类型:底座安装 尺寸/尺寸:102.36mm L x 67.31mm W 高度 - 座高(最大):66.80mm 端接类型:导线引线
ST7-28 制造商:SUPERWORLD 制造商全称:Superworld Electronics 功能描述:POWER TRANSFORMER
ST7-28B56 功能描述:电源变压器 SPLIT BOBBIN HORZ MOUNT XFMR RoHS:否 制造商:Triad Magnetics 功率额定值:12 VA 初级电压额定值:115 V / 230 V 次级电压额定值:12 V / 24 V 安装风格:SMD/SMT 一次绕组:Dual Primary Winding 二次绕组:Dual Secondary Winding 长度:2.5 in 宽度:2 in 高度:1.062 in