Introduction

Frequency-shift keying (FSK) is a digital modulation technique that involves varying the frequency of a carrier signal to transmit digital information. The carrier signal is shifted between two or more frequencies to represent different binary states in FSK. The frequency shift between the two states is typically low, and the signal is demodulated by detecting the frequency shift. FSK is commonly used in applications such as wireless communication, RFID, and telemetry systems.

The FSK modulation method that only uses two frequencies is called Binary FSK (BFSK). The carrier signal frequency is shifted between the two frequencies to represent the binary data, while the phase of the carrier signal remains constant during this process. The frequency used to represent a binary 1 is known as “mark,” while the one used to represent a binary 0 is known as “space.”

BFSK modulation and demodulation techniques using peripherals specific to the AVR® EB Family of microcontrollers (MCUs) are addressed in this technical brief. These techniques are implemented using the Timer/Counter Type F, E and B (TCF, TCE and TCB) peripherals. One code example was developed around the AVR16EB32 MCU, showcasing full-duplex communication between two Curiosity Nano (CNANO) boards through BFSK modulation and demodulation. The code example uses the MPLAB® Code Configurator (MCC) for the initial device and peripherals setup. It has a corresponding web page on the Microchip MPLAB Discover website, providing a comprehensive description of the hardware and software requirements.