# I2S EMULATION

## Overview

- This sample show use SPI transmit and receive audio data to audio codec
- The evaluation board needs to be connected to the audio decoding module. This example uses wm8978

## Notice

- Since the SPI used in this example requires a large transmission length, it currently only supports the hpm5300 series.

## dependent components

- dma_mgr
- spi
- i2s_over_spi
- codec(wm8978)

## Board Setting

- Recording via the onboard mic of the audio module
- Connecting 3.5mm headphones to the headphone output port of the audio module

- Need to use GPTMR output and SPI pins，pins(Please refer to  [Pin Description](lab_board_resource))

- 5V          <--> 5V(WM8978)
- 3.3V        <--> 3.3V(WM8978)
- GND         <--> GND(WM8978)
- MCLK(GPTMR) <--> MCLK(WM8978)
- LRCK(GPTMR) <--> (FSA)LRC(WM8978)
- BLCK(GPTMR) <--> SCLK(SPI) <--> SCK(WM8978)
- MISO(SPI)   <--> (DAT)DACDATA(WM8978)
- MOSI(SPI)   <--> (SDB)ADCDATA(WM8978)
- (CS)GPIO    <--> CS(SPI)
- I2C_SDA     <--> I2C_SDA(WM8978)
- I2C_SCL     <--> I2C_SCL(WM8978)

## Run steps

- When the project runs correctly, the serial port terminal will output the information like

```console

---------------------------------------------------------------
*                                                             *
*                   i2s_emulation demo                        *
*                                                             *
*        1 - start play                                       *
*        2 - stop play                                        *
*        3 - start record                                     *
*        4 - stop record                                      *
*-------------------------------------------------------------*

```

- Enter the '3' character into the terminal to start recording. If the recording duration is longer than the specified duration, it will automatically exit and save.

```console
record_start enter....
record size overflow, now exit..
```

- Enter the '1' character in the terminal to start recording playback

```console
play start enter....
play end, now exit....
```

- Enter the '4' character in the terminal to stop recording.

```console
record stop finish....
```

- Enter the '2' character in the terminal to stop playing
```console
play stop finish....
```