low power fm receiver andrew young november 17, 2008
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Low Power FM ReceiverLow Power FM Receiver
Andrew YoungNovember 17, 2008
OverviewOverview
Project Inspiration RequirementsDifferencesDesign Block DiagramDesign SchematicOperational FlowchartLCD LayoutQuestions
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InspirationInspiration2008 IEEE Student Contest
◦ Objective: Create low power FM radio receiver ◦ Can use commercially-available IC subsystems
Senior Design Project◦ Competition between two teams◦ Goal is lowest power consumption
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Design Requirements Receive FM radio from 88.1 to 107.9 MHz Output audio at > 4mW per channel to standard 32-
Ohm headphones (33-Ohm resistors used for testing) Adjustable volume/station Interact with user via LCD interface Entire design implemented on one PCB
Competition Testing: One supply source, < 15V DC Design allows for internal circuit inspection
Optional Extras: Display RDS data (station name, artist, song title) Any extra features (signal strength, station presets,
menu) My own customization – video games, easter eggs, etc.
DifferencesWhat is different about this
design compared to the senior design project?◦Extra features – Something cool to
add which takes advantage of already-existing components, such as the attached LCD and joystick (video game, perhaps?).
Design Block DiagramDesign Block Diagram
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FM Receiver IC
(Si4703)
Microcontroller
(ATMega32)
LCD/User Interface104.1
Headphone Amplifier
Schematic - Page 1Push Buttons
FM Receiver
ATMega32
Switching Power Supply
Voltage Adjustment
LCDPort A
Port B Audio L/R
Battery Output
Si4703 Comm
Schematic - Page 2Batteries (2x AA)
Clock Generator Headphone Jack
Audio Amplifier
Gain Adjustment
Potentiometers Noise Suppression
Input Coupling
ESD Protection
Audio L/R
Low Voltage Input
On/Off Switch
AVR Application Development
Codevision AVR IDE (Evaluation) ◦Limited to 2kB code size◦Built-in libraries (LCD, I2C, Power-
Save)
AVR Studio 4.0 ◦Used to debug and set clock rates,
voltage levels, fuses
Operational FlowchartOperational Flowchart
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Power onAVR
Initializes Receiver &
LCDSet to
Default Station & Volume
Receive RDS Data
Interrupt When Button Pressed
Determine Button Pressed
(Volume Up or Down, Tune Up or Down)
Receive Signal
Strength
Output Signal & RDS to
LCD
Send Appropriate Signal to IC to Change Volume/Station
Send Appropriate Signal to Receive Current
Volume/Station
Translate Data to LCD Output
Return from Interrupt
Idle
Interrupt
LCD LayoutLCD Layout
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104.1 - KZRZArtist – Song NameSig. █ █ █ █Vol. █ █ █ █ █ █ █ █ █
SummarySummaryDesigning Low-Power FM Radio Receiver w/ Inspiration: Senior Design CompetitionExtras: Features not required by the senior
design project, such as a video game using the 4x20 LCD and the attached joystick.
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QuestionsQuestions
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ATMega32 AVR
Silicon Labs Si4703
Headphone Amplifier – MAX9725