HOW DOES IT WORK?

AM/FM 2 Click is based on the Si4732, a broadcast AM/FM/SE/LW/RDS radio receiver from Skyworks. It features TDMA noise immunity, superior radio performance, high-fidelity audio power amplification, advanced AN/FM seek tunning, automatic frequency control (AFC), and automatic gain control (AGC). It also features a digital FM stereo decoder, programmable de-emphasis, advanced audio processing, and seven selectable AM channel filters. The Si4732 integrates an RDS/RBDS processor, which allows the embedding small amounts of digital information in conventional FM radio broadcasts.

The Si4732 can receive the FM band broadcast in a range of 64 up to 108MHz, and AM band from 520 up to 1710KHz. In addition, the receiver supports the SW band (2.3 – 26.1 MHz) and LW band (153 – 279 KHz). The AM/FM 2 Click uses an SMA connector and external antenna to receive both AM and LW radio signals, while it also comes with a PTH for usage with a wire antenna. The FM and SW bands use a 3.5mm audio jack and connected earphones as an antenna, although a wire antenna is left as an option over an additional PTH. The Si4732 can receive or transmit the FM signal over the antenna but can not use both modes simultaneously.

The audio signal from the output of the Si4732 is brought to the onboard 3.5mm female audio jack over the LM4910, eliminating the need for any external amplifier. There are four selectable digital sample precisions (8, 16, 20, and 24 bits). The sample rate can be set between 320000 and 48000Hz.

AM/FM 2 Click uses a standard 2-Wire I2C interface to communicate with the host MCU. The I2C address can be selected over the ADDR SEL jumper with 0 default position. In cases where the AM reception is too strong, the front-end attenuators can be engaged using the GP1 pin. The radio receiver has interrupt abilities, which can be used over the GP2 pin. Both GP1 and GP2 are turned off over unpopulated R8 and R9 resistor jumpers. To use them, you should solder 0Ω resistors. There is also an additional RST pin for resetting the radio receiver. The LM4910 features a low-power consumption shutdown mode activated over the ENA pin with LOW logic.

This Click board™ can only be operated with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

SPECIFICATIONS