Hi, I am using STM32F413ZHT6 micro-controller for one of my application. I need reference design for I2S interface. Datasheet has not explained much about the pins functionality.

[kumar singh]

..

[waclawek.jan]

Manufacturers of I2S-compatible devices notoriously label the signals in various ways.

The standard says:

3.0 THE I 2 S BUS

As shown in Figure 1, the bus has three lines:

• continuous serial clock (SCK);

• word select (WS);

• serial data (SD);

and the device generating SCK and WS is the master.

ST follows this nomenclature relatively well.

standard ST various manufacturers
SCK (Serial Clock) I2Sx_CK SCLK, BICK (Bit Clock)
WS (Word Select) I2Sx_WS LRCK (Left-Right Clock)
SD (Serial Data) I2Sx_SD SDIN/SDOUT, SDTI/SDTO, RXDAT/TXDAT, DACDAT/ADCDAT

There is an additional nonstandard but often used signal I2Sx_MCK/MCLK.

The SPI/I2S module in STM32 is simplex but the data direction is settable (Rx/Tx) that's why it's not marked at the pin, and it's marked as I2Sx_SD.

There are auxiliary stripped-down I2S-slave-only modules, I2SxExt - as they are slave-only and their WS and SCK clocks are connected internally to their respective "master" module, they have only a single pin brought out, I2SxExt_SD.

Refer to the F4 Disco boards (e.g. https://www.st.com/en/evaluation-tools/stm32f4discovery.html ) for reference, they have an I2S DAC on board. Maybe the EVAL boards have I2S device on board, too.

JW

[kumar singh]

Hi waclawek.jan,

Thanks for your reference. I wanted to know about I2S2_SD and I2S2ext_SD direction I will have a look at it in the discovery board. I hope it should help

Narendra

[waclawek.jan]

> I2S2_SD and I2S2ext_SD direction

It depends on how you set the SPIx_I2SCFGR.I2SCFG field in the respective modules (SPI2/I2S2 and I2S2Ext): if to transmit, the respective pin is output, if to receive, the pin is input. See the I2S subchapter of SPI chapter in RM.

This allows you flexibility in routing the PCB.

JW

[kumar singh]

Thanks for your clarification.

[Piranha]

SAI peripheral is much better for I2S and other audio protocols. It should be the first choice.