Download Low Power FM Radio Receiver

Low Power FM Receiver
Andrew Young
November 17, 2008
Overview
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Project Inspiration
Requirements
Differences
Design Block Diagram
Design Schematic
Operational Flowchart
LCD Layout
Questions
2
Inspiration
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2008 IEEE Student Contest
◦ Objective: Create low power FM radio receiver
◦ Can use commercially-available IC subsystems
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Senior Design Project
◦ Competition between two teams
◦ Goal is lowest power consumption
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Design Requirements
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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.
Differences
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What 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 Diagram
Headphone
Amplifier
FM Receiver IC
(Si4703)
Microcontroller
(ATMega32)
LCD/User
Interface
104.1
6
Schematic - Page 1
Push Buttons
Port A
LCD
Port B
FM Receiver
Si4703
Comm
ATMega32
Battery
Output
Switching Power Supply
Audio
L/R
Voltage
Adjustment
Schematic - Page 2
On/Off
Switch
Clock
Generator
Audio L/R
Batteries
(2x AA)
Headphone Jack
Gain Adjustment
Potentiometers
Noise
Suppression
Input
Coupling
Low
Voltage
Input
Audio Amplifier
ESD
Protection
AVR Application Development
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Codevision AVR IDE (Evaluation)
◦ Limited to 2kB code size
◦ Built-in libraries (LCD, I2C, Power-Save)
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AVR Studio 4.0
◦ Used to debug and set clock rates, voltage
levels, fuses
Operational Flowchart
Power on
Interrupt When Button Pressed
AVR Initializes
Receiver &
LCD
Determine Button Pressed
(Volume Up or Down, Tune Up
or Down)
Set to Default
Station &
Volume
Receive RDS
Data
Idle
Send Appropriate Signal to IC
to Change Volume/Station
Receive
Signal
Strength
Send Appropriate Signal to
Receive Current Volume/Station
Output
Signal & RDS
to LCD
Translate Data to LCD Output
Interrupt
Return from Interrupt
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LCD Layout
104.1 - KZRZ
Artist – Song Name
Sig. █ █ █ █
Vol. █ █ █ █ █ █ █ █ █
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Summary
Designing Low-Power FM Radio Receiver w/
 Inspiration: Senior Design Competition
 Extras: 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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Questions
13
ATMega32 AVR
Silicon Labs Si4703
Headphone Amplifier – MAX9725