Description:
This low cost Relative
Humidity / Temperature meter also calculates the dew point,
hence it's name the "DewPointer 9000". This is a
demonstration instrument that shows the capabilities of a
PIC microcontroller in a portable, battery powered
application. Based on a capacitive humidity sensor
(Sensirion SHT 11) the design has a single operating button.
When the button is first pressed, the PIC wakes up and
displays the: Temperature, Relative Humidity and the
calculated dew point. If the button is pushed a second time
the display alternates from degrees F to degrees C units.
After 15 seconds of no button presses, the PIC turns it's
own power off and goes to a power down state, hence the
battery life is nearly the shelf life of the battery itself.
Also included is an RS232 interface that not only can supply
power to the unit, but also turns the sensor into a data
logger by providing an ActiveX control interface to any 32
bit Windows programming language and applications like Excel
and Word.
- Single button operation,
LCD display.
- Display in either
Degrees F or Degrees C by pressing the On/Off
button.
- Uses a single Sensirion
SHT 11 sensor for both humidity and temperature
measurements.
- Relative Humidity
accuracy better than 3.5%.
- Temperature accuracy
better than 1 degree.
- Low power handheld
design.
- Data logging with an
included RS232 link and ActiveX control for easy PC
interfacing.
Closeup showing
the display in the Degrees Fahrenheit mode.
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