ECE 477 Design Review
Team 22  Txt Msg DJ
Garrett
John
Chris
Strzelecki Doherty McCabe
Kyle
Brown
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Outline
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Project overview
Project-specific success criteria
Block diagram
Component selection rationale
Packaging design
Schematic and theory of operation
PCB layout
Software design/development status
Project completion timeline
Questions / discussion
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Project Overview
The Text Message DJ is a standalone unit that
creates and maintains a party playlist based on
song requests sent from party guests via SMS.
Guests can send text messages containing
song names and the Text Message DJ will
automatically parse messages, sort requests,
and play the most popular by streaming from
the internet. In addition to playing the song
audio, the Text Message DJ will strobe lights in
sync with the beat of the currently playing
song. Settings are stored on a SD Card in plain
text.
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Project-Specific Success Criteria
1. An ability to receive and parse text messages
2. An ability to strobe and move lights in sync with
audio using the DMX512 protocol
3. An ability to queue songs based on the number of
votes each song receives and display the queue on
an LCD Screen
4. An ability to retrieve and play audio of requested
songs using an online streaming service through
an API
5. An ability to load configuration files from an SD
card
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Block Diagram
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Component Selection Rationale
Microcontroller Design Constraints
 3 UART/USART (RasPi, GSM, DMX 512)
 2 SPI - 250kBaud (SD Card, LCD)
 3 PWM (Strobe LED)
 1 ATD (Audio Equalizer)
 5 GPIO (Diagnostic LEDs)
 JTAG Programming and Debugging
ATxmega64A3U
• Fits all design constraints without exceeding
excessively
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Component Selection Rationale
Raspberry Pi
• Inexpensive
• Connects to Internet via Wi-fi
• Can interface with existing web-based music
streaming services
GSM Module
• Inexpensive
• Good documentation and service record
Shift Register
• Reduce connections external to PCB
• Save GPIO pins for debugging
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Packaging Design
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Packaging Design
• Rectangle shape:
– 6 x 9 x 2 inches
• Peripherals:
– 2 x 16 LCD on front Panel
– External Antenna
– Power and wifi LED indicators
– 6V power adapter in rear
– SD Card slot
– SIM Card
– Audio out
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Schematic/Theory of Operation
Voltage Regulators:
• 3 Different
Voltages Required
• Varying Current
Requirements
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Schematic/Theory of Operation
Microcontroller
• Function: Parse SMS messages, control external
DMX device/s, control strobe LED, control LCD,
manage song playlist, control raspberry pi
• Operating Mode:
3.3V
• Headers on all pins
for debugging
C/K
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Schematic/Theory of Operation
Raspberry Pi
• Function: Retrieve songs from internet,
output audio to external device
• Operating Mode: 5V @ 700mA – 1.2A
• Interface: UART: Port F
C/K
Schematic/Theory of Operation
GSM Module
• Function: Send and receive SMS messages
• Operating Mode: 3.8V @ 400mA – 2A
• Interface: UART: Port E
C/K
Schematic/Theory of Operation
C/K
Schematic/Theory of Operation
DMX Module/ RS 485 Level Converter
• Function: Translate Microcontroller Signal to
DMX 512 Signal
• Operating Mode: 3.3V @ 1mA
• Interface: UART: Port E
C/K
Schematic/Theory of Operation
SD Card Reader
• Function: SD card stores
setup files
• Interface: SPI: Port D
Microcontroller
bypass
capacitors
C/K
Schematic/Theory of Operation
Strobe LEDs/Control Transistors
• Function: Strobe to Music
• Operating Mode: 5V @ 1A
• Interface: PWM: Port A
Equalizer
• Function: Convert
Audio to Strobe
• Operating Mode: 3.3V
• Interface: ADC &
General I/O: Port B
Schematic/Theory of Operation
Other Components:
Diagnostic LEDs
Reset Switch
• General I/O: Port A • Reset Pin
Shift Register and
LCD Screen
• Display Playlist
• SPI & General I/O
– Port C
JTAG Header
• Port B: JTAG
PCB Considerations
PCB Considerations
Micro
GSM
DMX
SD Slot
LCD Header
Power
Equalizer
Debug LEDs
Strobe LED
Micro
Micro
Reset
JTAG
Power Filter
Power Supply Considerations
5V
3.8V
3.3V
Software Design/Development Status
• Microcontroller
– Event driven
– Triggers: serial input (UART) from GSM
Module and Raspberry Pi
• Raspberry Pi
– Event Driven
– Trigger: serial input(UART) from Micro
– Utilize ‘Twisted’ (Async Server Software)
– Chrome CLI
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Project Completion Timeline
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08-Mar: Final Schematic/PCB Layout
11-Mar: N/A (Txt Msg DJ Company Holiday)
20-Mar: Initial Software Design
25-Mar: Raspberry Pi Interface with Micro &
GSM Module/SIM on PCB
• 01-Apr: DMX Protocol/LCD Screen with
Queue on PCB
• 08-Apr: Strobe LED/ SD Card functional
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Project Completion Timeline
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15-Apr: PCB fully functional and assembled
17-Apr: Project Packaged
19-Apr: Completed User Manual
22-Apr: Final Test and Setup for Demo
24-Apr: Final Deliverables
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Questions / Discussion