Transcript presentation

ECE445: Senior Design
Spring 2015
Team 17: Weather Jukebox
Sang Yun Bang, Thomas Fedrigon, Shanda Lu
Introduction
• Check weather in morning without staring at bright screen
• Atmospheric songs set the indoor mood to be similar to outdoor temperatures
• Interesting and fun way to check weather!
Objectives
• Temperature/Humidity sensors collect current weather conditions
• Weather station wirelessly send data in real-time and updates LED lights
• Plays melody based on conditions when play button is pressed
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Block Diagram: Initial Stage
Top Level Block Diagram
Block Diagram: Final Stage
Top Level Block Diagram
Weather Station
Weather Station PCB
• 2 Layers custom PCB
• Top layer: Signals
• Bottom layer: Power/Ground
• Outer loop for power supply
PCB layout for weather station
DC-DC Converters
• DC-DC Converter: L7805
• Linear fixed voltage-5V
• Weather Station
• 9V DC Battery
• Jukebox
• 12V DC Wall outlet
DC-DC converter Eagle layout
DC-DC Converter for Battery
Battery
Output
Output of DC-DC Converter
Sensors
• Temperature Sensor: LM34 Texas Instruments
• Linear 10
𝑚𝑉
℉
output
• 0 to 100 ℉ -> 0 to 1 V expected
LM34 Eagle layout
• Typically 0.7-0.8 V read in lab (room temperature)
• Humidity Sensor: HIH-4030 Honeywell
• 𝑉𝑜𝑢𝑡 = 𝑉𝑠𝑢𝑝𝑝𝑙𝑦 0.0062 𝑠𝑒𝑛𝑠𝑜𝑟 𝑅𝐻 + 0.16
HIH4030 Eagle layout
Amplifier
• LM741 Texas Instrument
• Used to amplify temperature sensor output
• 𝐺𝑎𝑖𝑛 =
• 𝑉𝑜𝑢𝑡 =
𝑉𝑜𝑢𝑡
𝑉𝑖𝑛
LM741 Eagle layout
𝑅2 + 𝑅1 ∗𝑉𝑖𝑛
𝑅1
𝑉
𝑉
• For desired gain of 5 , 𝑅2 = 4 ∗ 𝑅1
• 𝑅2 = 4 𝑘Ω, 𝑅1 = 1 𝑘Ω
Non-inverting amplifier
Amplifier Gain
𝑉
Expected output vs input voltage for gain of 5 𝑉
Analog to Digital Converter
• ADC0808 Texas Instrument
DC Volts per Division Calculation
• After amplification of temperature sensor, both sensors output from 0 to 5 V
• ADC converts signals to 8 bits or 256 different values
•
𝑉𝑜𝑙𝑡𝑠
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝐵𝑖𝑡𝑠
=
5
256
= 0.0195
𝑉𝑜𝑙𝑡𝑠
𝐷𝑖𝑣𝑖𝑠𝑖𝑜𝑛
• Max error of 1.95 °F
ADC0808 Eagle layout
ADC Output vs Input
• Voltage ratio =
2.86
5
= .572
• .572 * 256 bits = 146.432
• LED output = 1001 0011 = 147
• % Error = 0.39%
LSB
Buffer Chips
• HCT125 Buffer chips
• Clock signal
• Sent to OE for D3-D0 buffer
• Inverted clock signal
• Sent to OE for D7-D4 buffer
• Output sent to corresponding pin of encoder
Buffer chip Eagle layout
Clocks
• LM 555 Timer
• Frequency =
1.44
𝑅1+2∗𝑅2 ∗𝐶
• Duty Cycle =
(0.7∗ 𝑅1+𝑅2 )∗𝐶
(0.7∗ 𝑅1+2∗𝑅2 )∗𝐶
=
(𝑅1+𝑅2)
(𝑅1+2∗𝑅2)
• ADC
• R1 = 1 kΩ, R2 = 10 kΩ, C = .01 𝜇F
• Expected: Frequency = 6.86 kHz, Duty Cycle = 52.38 %
• Buffer and Encoder
• R1 = 9.1 kΩ, R2 = 33 kΩ, C = 3.3𝜇F
• Expected: Frequency = 5.61 Hz, Duty Cycle = 56.06 %
LM555 Eagle layout
Clock Outputs
Buffer/Encoder Clock Output
ADC Clock Output
Freq: 5.70 Hz, Duty Cycle: 56.02%
Freq: 6.74 kHz, Duty Cycle: 51.57%
Clock Inverter
• 74ALS00 – 4 2-input NAND gates
• Operating as low frequency inverters
• Buffer/encoder clock to A and B
• Output to second set of buffer chips
7400 pin layout
NAND truth table
Encoder
• HT12E Holtek
• 8 address bits and 4 data bits
• Compatible with RF modules
• 750 kΩ used for on chip oscillator
HT12E Eagle layout
• Two sets of encoders
• Temperature encoded to address 0000000X
• Humidity encoded to address 0000001X
• Least significant bit (X) manipulated with same clock as buffer
• Allows bits to be decoded separately on jukebox side
Encoder Output
Oscilloscope output of encoder
Corresponding output of decoder
Transmitter/Receiver
• RF transmission
• Longer distance (80-120 meters in open space)
• Avoid interference using two transmitter/receiver pairs
• 434 MHz and 315 MHz
• ASK modulation
• Able to send digital data
Receiver Eagle layout
• Simplest to generate and detect
• Cheap
Transmitter Eagle layout
Jukebox
Jukebox PCB
• NOT efficient PCB
• Top/Bottom layer
• Signals, power, and ground
PCB layout for Jukebox
Decoders
• HT12D Holtek
• Four decoders for total of 16 bits of transmitted data
• 51 kΩ used for on chip oscillator
HT12D Eagle layout
Arduino Mega
• Planned Arduino Due
• Problem with interfacing
• Missing components
• Alternative plan
• Arduino Uno
Arduino DUE
• Arduino Mega
Arduino MEGA
Program Pseudo-Code
Flow chart for program
Serial Monitor Output
Debugging / Testing
• Verify the decoder is working
• Checking with serial monitor
LSB
Output of decoder
Future Improvements
• More sensors for (i.e. light, wind)
• Increased range
• Internet connectivity to double check sensor readings
• Visual reading of temperature/conditions on jukebox
• Industrial design for final goods
Questions?
Thank You!