So now our project has two potentiometers one to tune, and one to change the volume. I interchanged the pot, which is used to change the Gain, with a resistor. Instead of using two potentiometers in the amplifier, I used only one. The below pic shows the complete circuit diagram for Arduino FM Radio. To change the volume you can either vary the pot, which is connected in between 1 and 8 th pin of LM386 or the pot, which is connected at pin 3 of the LM386. We used two potentiometers for tuning the FM band and controlling the volume of the audio amplifier. We have built a simple audio amplifier using LM386, the circuit for the same is shown below and you can also check the link to learn more about this circuit, also check other audio amplifier circuits. So, I used a perf board and some male pins and soldered the module’s each pin to each male pin as shown in the pic below.Īn audio amplifier is an electronic device, which amplifies low-power electronic audio signals to a level where it is high enough for driving loudspeakers or headphones. We cannot directly use the module when connecting it to a circuit as the pins are closed by. Each register performs tasks like varying volume, changing channels, etc depending upon the bits assigned to them. In all 13 registers, some bits are reserved while some are R/W. The register addresses start with 00H, which is allotted to chip ID and ends with 0FH. The RDA5807 has 13 16-bit registers, each performing a particular function. The module uses I2C communication to communicate with the MCU, and the interface begins with starts condition, a command byte, and data bytes. When coming to rest and control interface selected, the module resets itself when VIO is Power up, and also supports soft reset by the trigger of bit1 from 0 to 1 of 02H address. The module works on the power supply of 1.8 – 3.3V.
The RDA5807 pinout diagram for the IC is given below. The DSP core manages the channel selection, FM demodulation, stereo MPX decoder, and output audio signal. The PGA amplifies the mixer output signal and then digitized with ADCs. The limiter prevents overloading and limits the number of intermodulation products created by adjacent channels. It has digital low-IF architecture and integrates a low noise amplifier (LNA), which supports the FM broadcast band (50 to 115 MHz), a programmable gain control(PGA), a high-resolution analog-to-digital converter, and a high fidelity digital-to-analog converters (DACs). Below fig shows the block diagram of the RDA5807M tuner. The module supports the worldwide frequency band of 50 – 115MHz, volume control and mute, programmable de-emphasis (50/75us), receive signal strength indicator and SNR, 32.768KHz crystal oscillator, digital auto gain control, etc. RDA5807 is a single-Chip FM stereo radio tuner module with a fully integrated synthesizer. We are going to use the RDA5807 FM receiver module in this project, which simplifies our circuit. Now, all we need to build is a receiver that can be tuned to certain frequencies, and receive those signals, and later to convert these electrical signals to audio signals. At the radio stations, they use frequency modulation to modulate the signal and then transmit the data. As the name implies, amplitude modulation (AM) modulates amplitude before transmitting a signal whereas, in frequency modulation (FM), the frequency of the signal is modulated before transmitting through the antenna. There are two methods in which a signal can be modulated namely AM and FM. The Radio stations convert electrical signals to radios signals, and these signals have to be modulated before being transmitted through the antenna. We will also use an Audio Amplifier along with the circuit to control the output volume of our Arduino FM Radio, sounds interesting right? So, let’s get started. We will use the RDA5807 FM Receiver IC with Arduino and program it so, play any FM radio station which can be tuned by the user with a potentiometer.
In this tutorial we are going to construct an Arduino FM Receiver, and add it to our project arsenal. FM Transmitter circuit without Inductor.In our previous tutorials, we also built few other FM Transmitters and Receivers that are listed below. Radio signals are always present in the air (which are broadcasted by the stations), and all we need is an FM receiver circuit to catch those radio signals and transfer them to audio signals. But not long ago we were all depending on local FM Radios to get the latest news and songs, slowly these Radios are losing popularity but in emergencies when the internet is down, radios place an important role to transmit information to the users. Today almost everyone uses their mobile phones to listen to music, news, podcasts, etc.