Transcript Document

APSC 100
Project #31: Home Weather Station
Group 31Q
Billy Smith
Jacob Black
George McDonald
Keith Brown
Supervised By
Dr. Geoff Lockwood
Project Manager Bob
November 2, 2002
APSC 100
Project #31: Home Weather Station
Presentation Overview
1. What We Learned
2. Our Goal
3. Preliminary Design
4. Components
5. Progress Report
APSC 100
Project #31: Home Weather Station
What We Learned
Tutorial #1:
- construction of circuits
- methods for measurement of
voltage, current, and resistance
Tutorial #2:
- operational amplifiers
Tutorial #3:
- analog-to-digital converters
- seven-segment displays
APSC 100
Project #31: Home Weather Station
Our Goals
1. Learn to build and analyze simple electronic circuits.
2. Produce an inexpensive weather station suitable for
home use, with the capability to measure readings in
the ranges of:
1. -40oC to +40oC
2. 0% to 100% humidity (±2%)
APSC 100
Project #31: Home Weather Station
Preliminary Design
Our circuit will contain the following:
•
LM555 Timer/Square Wave Clock
•
AD7819 Analog-to-Digital Converter
•
Temperature Transducer Circuit
•
Humidity Transducer Circuit
APSC 100
Project #31: Home Weather Station
Components of Circuit
1. LM555 Timer/Square Wave
Clock
2. AD7819 Analog to Digital
Converter
3. Temperature Transducer
Circuit
4. Humidity Transducer Circuit
APSC 100
Project #31: Home Weather Station
Component #1
(LM555 Timer/Square Wave Clock)
-
-
-
used to generate a squareroot wave
sends an analog clock signal
to the AD converter
square-root wave produces
intervals of reading/sampling
of the analog input signal
Pictures courtesy of National Semiconductor
APSC 100
Project #31: Home Weather Station
Component #2
(Analog-to-Digital Converter)
An AD789 linked with the
DM9368 common-cathode
display driver and a seven
segment display
-Convert analog signals
from the transducers to
binary codes
-Convert binary code into
a digital display
Picture courtesy of National Semiconductor
APSC 100
Project #31: Home Weather Station
Component #3
(Temperature Transducer)
-
-
-
LM35 precision
integrated-circuit
temperature sensor
±0.5oC accuracy
guaranteed (at +25oC)
Rated for –55oC to +150oC
range
Picture courtesy of National Semiconductor
APSC 100
Project #31: Home Weather Station
Minimum Supply
Voltage
Our given temperature
range produces a
fluctuation in signal of
±1V. An amplifier may
be required to make this
signal usable for our
purposes.
Picture courtesy of National Semiconductor
APSC 100
Project #31: Home Weather Station
Component #4
(Humidity Transducer)
-
HIH-3605-A
transducer circuit
allows us to read the
relative humidity
-
Send an analog
signal to the AD
(Analog/Digital
Circuit) converter
Picture courtesy of National Semiconductor
APSC 100
Project #31: Home Weather Station
Output Voltage
-
Transducer outputs
within target range of
AD Converter
Picture courtesy of National Semiconductor
APSC 100
Project #31: Home Weather Station
Final Progress Report
1. The clock and Analog/Digital Converter have been
constructed and tested
2. Next we plan to implement the temperature and
humidity transducers
3. Group cooperation is satisfactory and there are no
team issues to report