Web Site: www.parallax.com Office: (916) 624-8333 Forums: forums.parallax.com Fax: (916) 624-8003 Sales: sales parallax.com Sales: (888) 512-1024 Technical: support parallax.com Tech Support: (888) 997-8267 FM Radio Receiver Module ( 27984) The FM Radio Receiver Module uses an RDA5807SS FM stereo radio tuner chip, which provides an easy way for your microcontroller to receive local FM radio stations. Using the onboard antenna and headphone jack, you can easily create your own portable radio Features Onboard standard 3.5 mm TRS stereo headphone minijack provides easy audio output Supports the worldwide frequency band (76 to 108 MHz) No external antenna required 10-pin DIP package ready for breadboard or through-hole projects 2 Easy I C interface with virtually any microcontroller Key Specifications Power Requirements: 2.7 to 5.5 VDC 25 mA 2 Communication: I C Operating temperature: 32 to 121 F (0 to 50 C) Dimensions: 0.70 x 0.65 x 0.34 in (1.78 x 1.65 x 0.87 cm) Application Ideas Portable radio Digital radio alarm clock Theory of Operation The FM Radio Receiver Module uses the RDA5807SS FM stereo radio tuner chip to tune to FM radio stations on the worldwide frequency band. You can program this chip directly using and I2C interface through the SDA and SCL pins (for more detailed information, see the Register Table section on page 3. 2 An I C interface transfer begins with a START condition, a command byte and data bytes. Each byte is followed by an ACK (or NACK) bit, and then the interface transfer ends with a STOP condition. The command byte includes a 7-bit chip address and a Read/Write bit. The ACK (or NACK) is always sent out by the receiver. During a write transaction, data bytes are sent from the microcontroller, and during a read transaction, data bytes are read from the FM Radio Receiver Module. Copyright Parallax Inc. FM Radio Receiver Module ( 27984) v1.0 5/2/2011 Page 1 of 7 The FM Radio Receiver Module will send an ACK after every byte, and the microcontroller should issue a STOP condition when register programming is finished. Detailed timing diagrams can be seen in Figure 1 and Figure 2 below. Figure 1: Write Transaction Timing Diagram Figure 2: Read Timing Diagram The FM Radio Receiver Module also features an onboard stereo headphone jack. When headphones are plugged in, the ground wire of the headphones cable functions as an antenna. However, should better reception be needed, and external antenna can be connected to the FM Radio Receiver Modules ANT pin. Pin Definitions and Ratings Pin Name Type Function 1 SDA I/O Serial Data Line 2 SCL I Serial Clock Input (0 to 400 kHz) 3 ANT - External Antenna Connection Option 4 ROUT O Right Audio Output 5 LOUT O Left Audio Output 6 GPIO1 I/O General Purpose Input/Output 1 7 GPIO2 I/O General Purpose Input/Output 2 8 GPIO3 I/O General Purpose Input/Output 3 9 VDD P Supply Voltage -> 2.7 to 5.5 VDC 10 GND G Ground -> 0 V Pin Type: P = Power, G = Ground, I = Input, O = Output Copyright Parallax Inc. FM Radio Receiver Module ( 27984) v1.0 5/2/2011 Page 2 of 7