I’ve started to build a little FM radio with one of this cheap modules with a Phillip chip, the TEA5767. I will control it with a MSP430, probably I’ll use some kind of encoder to change stations and a potentiometer for the volume.
The TEA5767 is a single-chip electronically tuned FM stereo radio for low-voltage applications with fully integrated Intermediate Frequency (IF) selectivity and demodulation. Most of the information of this devices is from the datasheet and this app note.
The I2C-bus mode is selected when pin BUSMODE (PIN 3) is LOW.
The serial interface use pin 1 as SDA and PIN 2 as SCL. The board is powered with 3.3V with VCC being PIN 5 and GND in PIN 6. PIN 10 is there to connect an external antenna (just a piece of wire) and PIN 7 and 8 are the audio outputs. Pins 4 and 9 are left unconnected.
First of all let me explain some basics concepts about FM radio receivers in order to understand how to configure the different settings this chip has. I might be oversimplifying some things here, I’m just writing what I’ve read and understood while searching information to use this thing so beware of mistakes!
The super heterodyne is a circuit arrangement that is the basis of almost all modern radio receivers. Edwin Armstrong invented in 1918 the idea of a heterodyne receiver. Heterodyning is the translation of a signal from a higher Radio Frequency (RF) carrier signal to a lower Intermediate Frequency (IF). There are three important frequencies in heterodyne RX; RF Radio Frequency, the center frequency the signal is broadcast on; IF Intermediate Frequency, fixed frequency inside the RX (the RF signal is down converted to this frequency) and LO Local Oscillator, tunable frequency inside the RX used to translate the RF signal to the IF frequency.
Read More: Making an FM radio-Part 1; the TEA5767