1. Low Power FM Receiver
Andrew Young
November 17, 2008

2. Overview Project Inspiration Requirements Differences
Design Block Diagram
Design Schematic
Operational Flowchart
LCD Layout
Questions

3. Inspiration 2008 IEEE Student Contest Senior Design Project
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 3

4. 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.

5. Differences
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?).

6. Design Block Diagram Headphone Amplifier FM Receiver IC (Si4703)
Microcontroller
(ATMega32)
LCD/User Interface
104.1 6

7. Schematic - Page 1 Push Buttons LCD FM Receiver Voltage Adjustment
Port A
LCD
FM Receiver
Port B
Audio L/R
Si4703 Comm
Voltage Adjustment
ATMega32
Battery Output
Switching Power Supply

8. Schematic - Page 2 Batteries (2x AA) Clock Generator Headphone Jack
On/Off Switch
Batteries (2x AA)
Clock Generator
Headphone Jack
Gain Adjustment
Potentiometers
Noise Suppression
Audio L/R
Input Coupling
ESD Protection
Low Voltage Input
Audio Amplifier

9. 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

10. 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
Send Appropriate Signal to IC to Change Volume/Station
Idle
Receive RDS Data
Send Appropriate Signal to Receive Current Volume/Station
Receive Signal Strength
Translate Data to LCD Output
Output Signal & RDS to LCD
Interrupt
Return from Interrupt

11. LCD Layout 104.1 - KZRZ Artist – Song Name Sig. █ █ █ █
Vol. █ █ █ █ █ █ █ █ █

12. 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. 12

13. Questions

14. ATMega32 AVR

15. Silicon Labs Si4703

16. Headphone Amplifier – MAX9725