Unable to use I2S exampel on RTL8720DN

The I2S module is creating a blocker for us to evaluate the solution.

Currently, I am trying to use the I2S module on RTl8720DN in TX only mode. I am using Channel number 3 out of 6 channels of the I2S module. Since I2S_SD_TX1 is available in the package.

I am able to play the input file. but I am observing a few issues.

  1. The I2S output skips data frames. I am able to play the files but there are a few frames that are not present in the I2S output. I used a logic analyzer to observe the waveforms.

  2. Sometimes there are a few corrupted samples when the sample rate is 16000. For a sample rate of 12000, it works okay.

  3. For a page size of 768 bytes, sample rate of 12000, 16-bit samples, and 5.1 channel. I am expecting the test_tx_complete to fire approximately every 5 milliseconds but it firing 10 times faster than that.
    This could be the reason of skipped frames in output. But i am not sure why it is happening.

  4. In the user manual it is mentioned about LBK. I can not find any details on that. What is that and how to enable it?

  1. What is the purpose of the below interrupts. I am not able to find any details on this also.

  1. I can share the code for review. Please share me details on how to do it?

Please help me resolve this issue ASAP.

No I2S support on RTL8720 ICs, its only available on RTL8721 and RTL8722 ICs

If you are using BW16 module, I think it’s best that you refer to BW16’s official technical documents, where you can find no information about I2S support

I2S in TX mode channel 3, 4, 5 and 6 is available on RTL8720. I am not sure if it is official or not. I have tested it. But there are a few glitches.



Referring to the datasheet for the RTL872xD series of chips, in Chapter 1.4 package comparison, the I2S peripheral is not supported for RTL8720DN and RTL8720DM chips, and is only supported on RTL8720DF, RTL8721DM and RTL8722DM chips.

It is probable that the I2S peripheral on your chip did not meet performance specifications during the chip manufacturing and binning process, which led to that specific chip being downgraded and sold as a RTL8720DN without I2S support.


Now it makes sense.
Are there any modules available for RTL8721DM or RTL8722DM?


refer to this post for buying modules/ICs directly

Can I expect the I2S peripheral to work as expected in RTL8720DF?
Someone tested it?


Hi @Jitendra_Singh

This model is very new, I don’t think anyone in the community has acces to it nor to test it, the best way to confirm its function is via FAE or the PM