Transcript Automatic Volume Control

Automatic Volume Control
ECE 445
Team #23
Eric Davila
Roland Le Grand
Chris Goulet
4/30/13
Objectives
 Build a system which automatically adjusts the volume of
your speakers based on how far you are from them
 Functions with any bluetooth device and up to three speakers
Original Design
 High Level Block Diagram
Original Design
 Central Hub Diagram
Original Design
 Speaker System Diagram
Original Design
 Transmitter Diagram
Main Components
 Power Supply
 Speakers
 Microcontroller
 Sensors
 Transmitter
 Logic Unit
Power Supply
 Supply power to all components that don’t have their own
power supply- lots of wire will be necessary!
 Supply normal voltage levels like 3V, 5V, and 12V DC
 Receive power from the wall
Speakers
 The automatic sound
amplification takes place here
after receiving the signal
from the microcontroller,
then the music is played from
the transducer
 Amplification will be from a
variable op-amp circuit, then
that signal will be sent to the
actual speakers
Microcontroller
 Texas Instruments MSP430G2553
 Low cost
 62.5 ns instruction time
 Easy to set up
 Sufficient amount of IO pins
Sensors
WT 32 Bluetooth Audio Module From Bluegigga
•UART interface with Microcontroller
•3.3V power supply
Transmitter
 Samsung Galaxy S II
 Bluetooth v3.0 + HS
 3.7 Volt, Lithium Ion
1800mAh battery
Logic Unit
 Implemented with TTL logic
 Inputs = Analog signals from MCUs
 Outputs = Binary signal to indicate ON/OFF state
 Advantages:
 Low cost
 Low power consumption
 Disadvantages:
 Rigid implementation
 Number of parts
Design Adjustments
 The power supply actually only had to provide 3.3V and 5V
DC
 Variable op-amp circuit isn’t necessary, a digital
potentiometer will take care of volume amplification
Power Supply
 Reused an old computer power supply, a Bestec ATX-300-
12E, with DC outputs:
 +12V , 15A
 +5V, 30A
 +3.3V, 28A
 -12V, 0.8A
 +5VSB, 2A
 Only 3.3V, 5V, and ground outputs were necessary
Power Supply
 Issue: Many different
connections needed to be
made with long wires
 Solution: Use wire
disconnects for easy
connection variability and
wire nuts to merge many
wires from one
Power Supply
 Issue: not functioning properly when disconnected from the
computer
 Solution: after some research, I learned to connect the VSB
line (green) to ground (black)
 This caused the supply’s fan to turn and the voltages to read
correctly
 Issue: when different voltage lines touched, the supply was
shorted and stopped working for a while
 Solution: make sure that the loose ends are secure
Speakers
 3 GE 2.0 Multimedia Speakers so that every speaker would be as
loud as the others
 Removed the original volume control (mechanical
potentiometer) using vacuum soldering iron in the electronics
shop
Speaker Circuit
Ground Wire
Speaker #2 Output
Adjusted
Music from
Wiper
Speaker #1
Output
Neutral from
Music Source
Original Music
Input
Power Input
Speaker Setup
 The Digital Potentiometer Replaced the Mechanical
Potentiometer
Digipot Connections
 Important pins:
 Pin 1: INC- change
wiper
 Pin 2: U/D- wiper goes
up or down
 Pin 3: RH- input from
music source
 Pin 5: RW- output to
speaker circuit
Digipot Testing
 The digipot was successfully tested while the microcontroller
controlled it
 Results: 15 steps of 600Ω, resistance ranges from 100Ω to 9.1
kΩ
Logic Unit Schematic
Decode
r
Comparators
TTL
Logic
Logic Unit Schematic Cont…
Output Results
A (V1 > V2)
B (V1 > V3)
C (V2 > V3)
b1
b0
SPK 1
SPK 2
SPK 3
0
0
0
1
0
0
0
1
0
0
1
0
1
0
1
0
0
1
0
1
1
0
0
0
0
1
1
0
1
0
1
0
1
0
0
1
0
0
0
1
1
0
1
1
1
0
0
0
1
1
0
0
0
1
0
0
1
1
1
0
0
1
0
0
✓ All outputs are correct
Timing Results
Microcontroller
MSP430 Pin Layout
MCU Control Loop
Sensors
WT32 Configuration
•USB to DB9 through
voltage leveler circuit
to Serial UART
Shift converter
RSSI to Distance Mapping
100.00
95.00
90.00
85.00
80.00
RSSI VALUES
75.00
Absolute RSSI value
avg RSSI Values
70.00
store10 (using rsssiavg)
65.00
60.00
55.00
50.00
0
1
2
3
4
Distance (m)
5
6
7
8
RSSI to Distance Mapping
RSSI to Distance Error
6.00%
5.00%
4.00%
Absolute error
3.00%
2.00%
1.00%
0.00%
55
60
65
70
75
Absolute RSSI Value
80
85
90
95
Obstacles
 All three of the digital potentiometers burned up from too
much current
 Rated current: 50μA max, 5 μA standby
 Actual current: as much as .5V/100Ω = 5000 μA
 USB to serial conversion for BT configuration
 Garbled messaging over UART between MCU and BT
Future Work
 Purchase digipots that can handle much more current
 WT32 has many features to be exploited
 Put as many components on a single PCB as possible
Thanks
 Igor Federov, our TA
 Professor Carney
 The Electronics Shop guys:
 Mark Smart
 Wally Smith
 Skot Wiedmann
Questions?