ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Preliminary Design Review
Team: Wireless Nothing
Team members
Derek Lindberg
Sean McDevitt
Nick Ciocco
Eric Hoffman
Chris Browne
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
What is this Device?
• Two-way wireless communication between
to separate motorcycles.
• One-way wireless CD quality audio
streaming from a portable device’s audio
jack.
• Adjustable volume, microphone gain, and
channel selection.
• Restricted access to broadcasted audio.
• Modular implementation of a wireless
communication and audio listening device
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
High Level Concept
Short range RF
Long Range RF
Short range RF
Preliminary Design Review
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Functional Block Diagram - Headset
Microphone
Microcontroller
Headphones
I2C
ADC Codec
I2C Bus
I2S
DAC Codec
I2S
Transceiver
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Transceiver
ADC/DAC – OR – Transceiver
——I2S——
Receiving
Transceiver
Transceiver
——I2C——
Microcontroller
Preliminary Design Review
Single Chip Wireless Transceiver (nRF24Z1)
• 2.4 GHz operating frequency
• Low cost
• Low power
• High-fidelity sound (16-bit)
• Channel selection
• Integrated control channel
• 1Mbit/s – 4Mbit/s Data Rate
• I2S or S/PDIF Audio Input (16bit)
• SPI or I2C
• Integrated Frequency Hopping Scheme
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Antenna Considerations
2.4 GHz Printed Monopole
• Size ~ 23cm x 1.5mm
2.4 GHz Chip Antennas
• Size ~ Tiny < 1cm2
• Reduced gain from reduced size
2.4 GHz Printed Whip Monopole
• Size ~ 12mm x 20mm
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Functional Block Diagram – Headset, DAC/ADC
Microphone
Microcontroller
Headphones
I2C
ADC Codec
I2C Bus
I2S
DAC Codec
I2S
Transceiver
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
DAC/ADC
Microphone Headphones MP3 Player
——Analog——
DAC / ADC
——I2C——
Single Chip DAC/ADC I2S Codec
• Convert between analog and I2S
• Low power low cost
• High quality 16 bit sound
• DAC and ADC in single chip for simplicity
• Integrated gain control, volume control and
speaker drivers if possible
• I2S communication to Transceiver
• I2C control from Microcontroller
——I2S——
Microcontroller Transceiver
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Functional Block Diagram - uC
Microphone
Microcontroller
Headphones
I2C
ADC Codec
I2C Bus
I2S
DAC Codec
I2S
Transceiver
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Microcontroller
Microcontroller
——I2C——
Transceiver(s)
ADC/DAC
Primary Functions
• Timing
• Control power consumption
• User feedback (tones, battery level)
• Process user input (buttons)
Microcontroller (MSP430F156)
Features
• 24kB Flash, 1024B RAM
• Very-low power
• 330uA active
• 1.1uA standby mode
• 12bit DAC
• I2C and SPI interfaces in hardware
• 48 IO pins
Overkill, but we will never have to worry
about exceeding code space or having
too few IO pins during dev.
Preliminary Design Review
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
State Diagram – Headset
Tx
Always
Init
Base Station Found
Base Station
Search
Wait
Idle
Wait
Rx
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
High Level Concept
Short range RF
Long Range RF
Short range RF
Preliminary Design Review
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Functional Block Diagram – Base Station
Microcontroller
I2C
Base Station
to Helmet
Transceiver
I2C/I2S Bus
Base Station to
Other motorcyclist
Transceiver
Preliminary Design Review
Base Station to
Audio Device
Transceiver
• Serves as a booster for
the helmet’s voice
communications
• Receives voice from
helmet and retransmits
with larger gain
• Receives voice
communication from other
motorcyclist(s) and
transmits them to the
helmet
• Given input from helmet,
switches between voice
communication and music
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
State Diagram – Base Station
Remote
Tx/Rx
Headset
Search
Wait
Idle
Wait
Local
Audio
Preliminary Design Review
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Voice Timeout
Init
Headset Found
Voice Detected
Always
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
High Level Concept
Short range RF
Long Range RF
Short range RF
Preliminary Design Review
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Functional Block Diagram - Media Device
Media Device
Microcontroller
Analog
I2C
ADC Codec
• Transmits streaming wireless audio from a
portable device such as an mp3 player
• Audio is played back in the helmet
• Has a lower priority than voice comm
• Same PCB as Helmet
• (headphone portion left unpopulated)
• Simplifies Design
• Single circuit to debug
I2C Bus
I2S
Transceiver
Preliminary Design Review
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
State Diagram – Media Device
Always
Init
Base Station Found
Base Station
Search
Wait
Preliminary Design Review
Idle
Wait
Audio Levels
Present
Remote
Tx
Audio Timeout
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Highly Modular Design
Wireless Audio
Transmitter
Base Station
Headphone/Mic
Audio
Codec
Tx/Rx
Audio
Codec
Tx/Rx
uC
Tx/Rx
uC
uC
Tx/Rx
Audio
Codec
Tx/Rx
• Each component is composed of several re-useable modules
• We only need to do low-level design and testing once
Preliminary Design Review
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Division of Labor
Team members
Responsibility
Derek Lindberg
Hardware layout and assembly,
firmware programming
Sean McDevitt
Antenna and Transceiver design
Nick Ciocco
Transceiver design and PCB layout
overview
Eric Hoffman
Hardware layout and assembly,
firmware programming
Chris Browne
Assembly firmware programming,
hardware integration
Group Responsibilities
• Documentation, system development, integration, system testing, and
documentation
Preliminary Design Review
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Project Timeline
Preliminary Design Review
Handmade by Robots
ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Risks and Contingencies
Risks
• Unfamiliar Interfaces and Devices
• I2C/S, Transceiver, Codec
• Difficulty controlling codec/transceiver
w/ uC
• Limited transmit range / Problems w/
interfering devices
• Lead time on components / Availability
problems
• Difficulty getting RF link working
• (RF protocol)
• Compliance with FCC regulations
Preliminary Design Review
Prevention
• Help from TAs, Manufacturers, Dev
Boards
• Nordic, Texas Instruments
• May be short range for Expo
• Ordering samples far ahead of time
• Use Nordic dev board
• Will ignore them
Handmade by Robots
ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Questions ?
Preliminary Design Review
Handmade by Robots