OVMS3-idf/examples/peripherals/i2s/README.md

I2S Example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

In this example, we generate a 100Hz triangle and sine wave and send it out from left and right channels at a sample rate of 36kHz through the I2S bus.

How to Use Example

Hardware Required

• A development board with ESP32 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
• A USB cable for power supply and programming

Configure the Project

idf.py menuconfig

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

Running this example, you will see the Bits per Sample changes every 5 seconds after you have run this example. You can use i2s_set_clk to change the Bits per Sample and the Sample Rate. The output log can be seen below:

Test bits=24 free mem=293780, written data=2880
I2S: DMA Malloc info, datalen=blocksize=480, dma_buf_count=6
I2S: PLL_D2: Req RATE: 36000, real rate: 37878.000, BITS: 24, CLKM: 11, BCK: 8, MCLK: 13837837.838, SCLK: 1818144.000000, diva: 64, divb: 36

Test bits=32 free mem=292336, written data=2880
I2S: DMA Malloc info, datalen=blocksize=480, dma_buf_count=6
I2S: PLL_D2: Req RATE: 36000, real rate: 36764.000, BITS: 32, CLKM: 17, BCK: 4, MCLK: 9216921.692, SCLK: 2352896.000000, diva: 64, divb: 23

Test bits=16 free mem=293772, written data=1440
I2S: DMA Malloc info, datalen=blocksize=240, dma_buf_count=6
I2S: PLL_D2: Req RATE: 36000, real rate: 36764.000, BITS: 16, CLKM: 17, BCK: 8, MCLK: 9216921.692, SCLK: 1176448.000000, diva: 64, divb: 23

If you have a logic analyzer, you can use a logic analyzer to grab online data. The following table describes the pins we use by default (Note that you can also use other pins for the same purpose).

pin name	function	gpio_num
WS	word select	GPIO_NUM_15
SCK	continuous serial clock	GPIO_NUM_13
SD	serial data	GPIO_NUM_21

Troubleshooting

• Program upload failure

  • Hardware connection is not correct: run idf.py -p PORT monitor, and reboot your board to see if there are any output logs.
  • The baud rate for downloading is too high: lower your baud rate in the menuconfig menu, and try again.

For any technical queries, please open an issue on GitHub. We will get back to you soon.