![]() In the below diagram, the timing sequence is shown: Therefore, the serial clock has a frequency of 44.1 kHz * 8 * 2 = 705 kHz. The formula that can be used to get the frequency is:įrequency = Sample Rate x Bits per channel x Number of channels. This BCLK line frequency is dependent on the sample rate, Bits per channel, and the number of channels it is using. It is used to get all components on the same cycle. As suggested in the name, it is a clock pin and it is important in the serial data communication protocol. The last and most important pin of the I2S communication is the Serial Clock (SCK) also called the bit clock line (BCLK). If the WS of the receiver is less than the WS of the transmitter, the bits after the LSB are ignored. If the WS of the receiver is greater than the WS of the transmitter, the word is truncated where the least significant data bits are set to 0. This is solved using the WS pin or WS line. This opens a new problem, since the receiver and the transmitter do not know the word length, it becomes difficult to match the data since it can be lost during data transmission due to noise and other factors. Thus, if the MSB is first transmitted, there would be no dependencies for the transmitter and the receiver to know how many bits are transferred or coming in. In I2S, the data can be in different word lengths that are transmitted from the transmitter to the receiver. In I2S data transfer, the most significant bit (MSB) is transferred first making it an MSB first data line. The transmission of data through this line uses the 2 complements method. This second line of the I2S communication protocol is the Serial Data or the SD Pin that carries the data signal. Irrespective of the above channel selection pin, the I2S protocol uses two additional pins that are most common in any serial interface. If WS pin = 1 then Channel 2 or Right channel is activated If WS pin = 0 then Channel 1 or left channel is activated Generally, If the WP pin is in Low state, Channel 1 or the Left channel is selected, on the other hand, if the WS pin is in the High State, the right channel is used. Since the I2S protocol uses both stereo operations, the channel left or Right can be selected using the WS or Word Select pin. Word Select (WS) or Frame Select (FS) wire: The connection between the transmitter and the receiver is shown below. The I2S protocol uses three wires for communication. Let's Explore what are the key points and how this I2S Protocol works in microcontroller units. We have previously used I2S communication to build an Internet Radio using ESP32, you can also check that project out if interested. The I2S protocol is designed by Philips Semiconductor, now NXP Semiconductors and it is widely used in different microcontrollers, codecs, audio modules, microphones that use this protocol to communicate the data. One of the simplest and probably the best ways is to use the I2S protocol that uses simple pin configurations and communicates between two digital audio devices. There are multiple Audio protocols available in electronics where audio codecs, DAC (In case of Audio output), or ADC (In case of Audio input) are used. ![]() There are many applications where audio communication is required in digital devices such as adding a microphone or adding a speaker output to play some audio. I2S is an Inter-IC Sound protocol that is used mainly to transmit or receive the audio data in a synchronous serial port between two devices.
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