I2S PROTOCOL

EXPLAINED                 

I2S, also known as Inter-IC Sound, is an electrical serial bus interface standard for communication between digital audio data integrated circuits (ICs). It's commonly employed to facilitate communication between digital audio processing chips, such as digital-to-analogue converters (DACs), and microcontrollers or digital signal processors (DSPs). This is often used to carry PCM information between the CD transport and the DAC in a CD player.

Several connector styles can be used to make an I2S connection between devices; however, several pinout specifications around the industry are not directly compatible with one another. All Bricasti products have a proprietary I2S connection, meaning that these products must only be used with one another.

I2S consists of no less than 3 data lines that work in unison to deliver unadulterated bit-perfect digital data and is usually only used inside audio equipment.

The I2S bus separates clock and data signals, resulting in a very low jitter connection. Jitter can distort a digital-to-analogue converter, and since the clocking is sent separately from the signal in I2S, no signal-induced jitter is introduced.

No error correction is present in the interface bus, so the receiver must synchronise with the transmitter.

I2S TIMING

PRECISION            

The bus consists of at least three lines:

Data Lines:

  • Bit Clock (SCK, also called Bit Clock – BCLK): Indicates the rate at which bits are transmitted.

  • Word Select (WS, also called Left Right Clock – LRCLK): Marks the beginning of a word and indicates whether the left or right channel is being transmitted.

  • Data Line (SD or SDATA): It carries the audio data with the Most Significant Bit (MSB) first.

 

Master Clock (MCLK):

  • Master Clock (MCLK): In some cases, an additional line called Master Clock is used for synchronisation with digital filters, oversamplers and DSPs. This clock signal may be provided by the master device to ensure proper timing.

Data Format:

I2S follows a standard format for transmitting audio data. This typically includes information for left and right audio channels, synchronisation signals, and clocking information.

 

Applications:

I2S is widely used in various audio applications, including but not limited to:

  • Audio codecs

  • Digital audio interfaces

  • Sound cards

  • Amplifiers

  • Digital audio processors

Advantages:

I2S is preferred in audio applications due to its simplicity, efficiency, and ability to transmit high-quality audio data without significant signal degradation.

 

Conclusion:

Overall, I2S plays a crucial role in digital audio systems, enabling the transfer of high-fidelity audio data between different components in a reliable and standardised manner. Because I2S is suitable for short-distance communication within electronic devices, only cables recommended by the manufacturer must be implemented in short runs. For longer runs, SPDIF, and particularly AES/EBU, will allow more flexibility for connection over longer distances.