SHT3x-DIS传感器警报模式：湿度和温度监控
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更新于2024-09-08
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"这篇文档是关于SHT3x-DIS传感器在电子领域的应用，特别是其Alert Mode功能在STM32-F0/F1/F2单片机/嵌入式系统中的使用。SHT3x-DIS是一款高精度湿度和温度传感器，具备警报模式功能，可以在周期性数据采集模式下监控环境条件，并在测量值超出预设限制时通过ALERT引脚发出信号。"
在电子工程，尤其是单片机和嵌入式系统设计中，SHT3x-DIS传感器是一个重要的组件，因为它能够提供精确的温湿度监测。该传感器具有Alert Mode特性，允许用户根据编程设置的界限来监控环境的湿度和温度。当环境条件超过这些界限时，传感器的ALERT引脚状态会发生变化，这为系统提供了实时的报警机制。
例如，ALERT引脚可以直接连接到一个简单的电路，如一个晶体管，以控制LED灯的开关或启动气候控制系统，从而大大减少了所需的材料成本。此外，ALERT引脚还可以连接到微控制器的中断引脚，使得在接收到SHT3x传感器的报警信号后，微控制器可以从低功耗睡眠模式唤醒，执行相应的处理任务，如记录数据、调整设备运行状态等。
激活和停用Alert Mode的过程非常灵活。只要传感器处于周期性数据采集模式，Alert Mode就会默认启用。用户可以独立地对温度和湿度的上限和下限进行设置，当将最小设定点设置为大于最大设定点的值时，即可关闭相应参数的报警功能。
在STM32-F0/F1/F2系列的微控制器中，这种传感器的集成尤为便捷。这些微控制器通常具有丰富的GPIO（通用输入/输出）端口，可以方便地与SHT3x-DIS的ALERT引脚连接，实现中断服务例程，进一步增强了系统的实时性和响应能力。同时，由于STM32系列微控制器的低功耗特性，结合SHT3x-DIS的Alert Mode，能够在满足节能需求的同时，确保对环境变化的快速反应。
SHT3x-DIS传感器的Alert Mode为电子和嵌入式系统提供了高效、节能的环境监控解决方案，尤其适用于需要实时监控温湿度并作出响应的应用场合，如智能家居、农业自动化、工业环境控制等领域。通过与STM32系列微控制器的配合，可以构建出高性能、低成本的环境监控系统。
www.sensirion.com D1 Version 1 – May 2015 1 /4
Alert Mode of SHT3x-DIS
Allows to use SHT3x-DIS as a humidity and temperature watchdog
SHT3x-DIS features an Alert Mode, when operated in the
periodic data acquisition mode
1
. The Alert Mode allows to
monitor the environmental condition (humidity and
temperature) relative to programmable limits. When limits
are reached the value of a dedicated ALERT pin will change.
Additionally, a status register bit indicates the cause of the
alert. Using the ALERT pin allows to create a switch with a
minimal bill of materials. For example, only a transistor is
needed next to the sensor to switch an LED on or start a
climate control.
Alternatively, the ALERT pin may be connected to the
interrupt pin of a microcontroller. After an alert from SHT3x
the microcontroller can wake-up from sleep mode and then
perform certain actions.
1 Activation and Deactivation of the Alert
Mode
Whenever the sensor operates in periodic data acquisiton
mode the alert mode is active. It is possible to deactivate the
limit for temperature and humidity individually, by setting the
Minimum set point to values higher than the Maximum set
point (LowSet>HighSet for deactivation of the alert mode).
2 Alert Mode Limits
The limits can be controlled by the user through the
corresponding commands (see Table 2). SHT3x-DIS allows
to set different limits for temperature and humidity as well as
for high and low limits. Additionally, the activation and the
deactivation of the alert can be controlled seperately from
another, by choosing the set and clear limit appropriately.
This allows to remove fast oscillations of the ALERT pin
close to set limit values. The different limits are shown in
Figure 1.
1
See Datasheet SHT3x-DIS Section 4 for the distinction between
periodic and single shot mode.
2.1 Data Format for the Alert Limits
The sensor stores the limit information in a reduced data
format. The standard data format of SHT3x-DIS has a width
of 16 bits. For the limits only the most significant bits (MSB)
are used to determine whether an alert has been met (7 bits
for humidity and 9 bits for temperature), see Figure 2.
Figure 2 Relevant Bits for the limits
This allows to transfer temperature and humidity limits with
the same command and to process them internally more
efficient.
As a consequence the limits have a different resolution than
the measurement values. The resolution of the temperature
limits are T≈0.5°C, whereas the humidity limits can be set
with a resolution of RH≈1%. Please note that data is
always measured and stored in the full 16 bit format. The
reduced data format is only used to judge whether an alert
condition is met.
Figure 1 Different limits for the Alert Mode
Tem
perature
or Hum
idity
Alert Pin
Output
high
low
LOW Set
LOW Clear
HIGH Set
HIGH Clear
High Alert ON
Low Alert ON
Alert OFF
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