ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Critical Design Review
Wireless Nothing
Team members
Derek Lindberg
Sean McDevitt
Nick Ciocco
Eric Hoffman
Chris Browne
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Project Overview
• Two-way wireless communication between two
separate motorcyclists.
• Low-power, low-profile design for easy
installation/integration inside helmet.
• Adjustable volume, microphone gain, and
channel selection.
• Restricted access to broadcasted audio.
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
High Level Concept
Long range RF
Short range RF
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Initial Set-backs – Wireless Transceiver
• nRF24Z1 – Only a point to point streaming device.
• Not capable of handling TDD (time division
duplexing) or FDD (frequency division duplexing).
• nRF24L01 – Great device, but not yet in full production
• Possible future use if breakout boards available
• nRF2401a – Current selection
• Fastest data-rate for a “true” transceiver
• Requires additional packet handling
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Initial Set-backs - Codec
• TI TLV320AIC28
• I2C control format
• QFN package
1
• TI TLV320AIC33
2
3
• Not available (just released)
• QFN package
• Xemics XE3006
4
• Audio format is standard serial (not I2S)
• Not available in quantities under 62
• TI TLV320AIC23B
• Available with all needed features
• SOP package
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
System Block Diagram - Headset
Microphone
Microcontroller
Headphones
DAC Codec
ADC Codec
Transceiver
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Block Diagram – Basestation
Basestation
to helmet
transceiver
SPI Bus
Basestation
to other
motorcyclist
transceiver
• Serves as a booster for the
helmet’s voice
communications
• Handles channel allocation
for slave headset
Microcontroller
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Microcontroller – MSP430F1611
Microcontroller
• 48kB Flash, 1024B RAM
• Extremely-low power
• 330uA active
• 1.1uA standby mode
• Dual 12bit DACs
• SPI interface in hardware
• 48 IO pins
• RS232 Interface via MAX3222 transceiver
——SPI——
Transceiver(s)
Critical Design Review
• HANDLING SPI/I2S
Audio Codec
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Timing Diagram I2S/SPI
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Main System (Base Station) Schematic
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Transceiver – nRF2401a
Receiving
Transceiver
•
•
•
•
2.4 GHz operating frequency
Low cost
Low power
1Mbit/s ShockBurst Data Rate
• Low on-air time
• SPI Communication
• Dual-channel receiver (2Mbit/s)
• Simple PCB antenna
Transceiver
——SPI——
Microcontroller
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Audio Codec – TLV320AIC23B
Microphone
Headphones
——Analog——
•
•
•
•
•
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
• SPI control from Microcontroller
Audio Codec
——I2S——
Microcontroller
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Current Project Plan – Divide and Conquer
• Printed circuit board tasks
• Assemble
• Test and debug
• Begin second PCB revision
• Dev. board tasks
• Establish communication between
transceivers
• Experiment with data rate limitations using
• Test maximum range and acceptable error
rates.
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
MSP430F1611 Dev. Board with nRF2401a
• Prototype Base Station
• Provides test bed for extended functionality
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Printed Circuit Board Rev. 1
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Risks
• Difficulty making SPI communicate with I2S
• High speed data rate and clock rate
• Unknown transmitter packet error rate at 1Mbps
• Difficulty with QFN package type (reflow)
• Wireless protocol complexity may be underestimated
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Backup Plan
 Use MSP430F1611 internal ADC/DAC
 SPI communication with I2S is removed
 Use lower data rate for transceiver
 Voice still possible and known implementation at
this data rate exist
 Out-source transceiver assembly or use breakout
boards from SparkFun
Critical Design Review
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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
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Project Timeline
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Milestone 1 – March 23rd
• Printed circuit board assembled, tested, and debugged
• Microcontroller communicating with all peripherals
• Simple high-speed data transmission between two
transceivers on development board
• Determine if addition of portable audio is feasible
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Milestone 2 – April 20th
• Preliminary voice communication up and running
• Microphone in and headphone out
• Base station to headset acquisition
• Preliminary protocol functionality
• Preliminary portable audio capability, pending Milestone 1
Critical Design Review
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ECEN 4610
Spring 2006
Hands-Free Low-Profile Wireless Radio
Budget/Final Parts List
Parts (per board)
Cost
Active Components
$60.00
Misc. Parts (all passive components)
$5.00
Misc. Connectors
$5.00
Total
$70.00
Total (est. qty. 100)
$30.00
Budget Breakdown
Qty
Cost
Base Stations
2 boards
$140.00
Headset
8 boards
$560.00
PCB
2 revs
$300.00
Total
Critical Design Review
--
$1,000.00
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
Questions ?
Critical Design Review
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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
Critical Design Review
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ECEN 4610
Hands-Free Low-Profile Wireless Radio
Spring 2006
State Diagram – Base Station
Remote
Tx/Rx
Headset Found
Wait
Idle
Wait
Voice Timeout
Headset
Search
Init
Voice Detected
Always
Headset Lost
Local
Audio
Critical Design Review
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