Getting ESP32 working with a new DAC

[edholness-starkstrom]

Hi,

I have a basic setup working with an Adafruit DAC and have been playing around with a board based around the Richtek RT9120S which is an amplifier with built in I2S. Trouble is, I can't get sound out of it yet. It looks like the board is not receiving a valid I2S signal so I am guessing there is something wrong with the I2S configuration I am using. I believe my wiring is correct as it should be just a 3 wire connection.

My question is: is there a particular strategy to take when trying to get a DAC working with ESP32 when it is not already documented? Obviously there are a bunch of boards that are documented so someone/some people have obviously done a lot of work on working out the required configuration for these devices, were there any particular strategies taken to get to this point?

I have read the documentation for the device although can not say I am an expert on this area so here it is for reference:
https://www.richtek.com/assets/product_file/RT9120S/DS9120S-00.pdf

This is what I have at the moment:

auto cfg = I2S.defaultConfig(TX_MODE);
 cfg.i2s_format = I2S_STD_FORMAT;
 cfg.is_master = true;
 cfg.pin_bck = 14;
 cfg.pin_ws = 27;
 cfg.pin_data = 26;

I have experimented with changing the mode, just for the sake of ruling anything out. On RX_MODE errors were printed to the Arduino IDE console which rules this out as a working option. TX and RXTX modes don't give errors which suggests either of these should be working, although I believe I only need TX.

I have also tried all option of format available, with no luck. The Adafruit board I tried before required LSB but this board should work with standard I2S, Left-justified, Right-justified or TDM formats.

Is there some kind of testing that could be done with the device to see what settings it needs? Maybe some kind of test program which runs through all settings in turn to see if anything works? Or is it just a case of trying all options available manually and seeing if anything works? Are there any other settings I should be experimenting with.

Thanks for any pointers anyone may have.

[pschatzmann]

You will need to control the chip over I2C, it isn’t free-running!

[edholness-starkstrom]

Thanks Phil,

So you think the chip needs an I2C command to start? Are there any examples of other DACs where this has been documented so that there is some kind of starting point to work from?

[pschatzmann]

Just read the technical sheet that you have attached above:

• The starting point is the Initial Sequence
• I guess the I2S_CLK_FMT and I2S_DATA_FMT might be of primary interest as well