One way to find out what mode the dac chip is configured for is to use a logic analyzer to watch the MCU configure the dac chip at power up, etc.
Another way might to let the MCU configure the dac chip registers, then disconnect the MCU and connect an Arduino or other MCU of choice to read back the registers.
How easy either of those things might be to do probably depends on how the I2C bus is laid out on the PCB. Is there an easy way to attach to it or modify it that doesn't require expensive micro probes for an analyzer?
The good news is that for I2C decoding a cheap $10 logic analyzer usually works fine. Arduinos are cheap too, but a little more complicated by the time everything is working.
Another way might to let the MCU configure the dac chip registers, then disconnect the MCU and connect an Arduino or other MCU of choice to read back the registers.
How easy either of those things might be to do probably depends on how the I2C bus is laid out on the PCB. Is there an easy way to attach to it or modify it that doesn't require expensive micro probes for an analyzer?
The good news is that for I2C decoding a cheap $10 logic analyzer usually works fine. Arduinos are cheap too, but a little more complicated by the time everything is working.
Thanks, but it looks like I'm lucky because my external DAC doesn't need any MCLK signal at all from the I2S (confirmed by the manufacturer) so it should work with sent out I2S over HDMI signal from the marked/labelled BCK, LRCK and DATA pins only from the M500 audio board: M500 DAC I2S input
I'm waiting for my M500 unit from China...
I guess the 1. is the GND
It looks I'd need four these pins only:
4. BCK
3. LRCK
2. DATA
1. GND
The M500 unit is on its way to me.
I already bought an inverted pinout HDMI board what is compatible with the Holo DAC I2S input.
- let's see the result soon
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OK, but let's see the result first.
Anyway, please send me your offer in PM.
I have two possible plans now:
1: Creating a I2S (over HDMI) output to the original M500. In this case the external and internal DAC could operating same time
2: Removing the Audio (DAC) board and it will have digital outputs only. (I2S, AES, Coax and Optical S/PDIF)
I'm planning to mod a Topping D90 MQA unit too with additional I2S output. The D90 has better clocks. I'll test them is it better the D90 or not with the same external DAC.
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Hi Cartman,
if I understand correctly, do you want to unfold the MQA signal and then pass it on to the R2R-DAC?
I'm sorry to disappoint you, but it can't work that way.
The complete development of the MQA signal is a complex process that does not only take place in a processor in front of the D / A converter. For this purpose, additional specific digital filters are used for the D / A converter used, which were derived from the A / D converter originally used.
If you redirect the signal to another D / A converter, it cannot work.
Hi Roland968,
Let's see this from another way
:The whole MQA decoding/unfolding is belongs to the XMOS device in case of M500 and other units with XMOS XU216 USB input. I'm 100% sure.
The used ES9038Pro DAC chip doesn't have ANY MQA related features at all.
There is no existing any I2S signal which contains MQA codec. So the I2S signal should be 100% unfolded already before taking it over to the DAC chip.
So, the ES9038Pro DAC chip doesn't know that the given Hi-Res I2S signal was original Hi-Res PCM or Hi-Res PCM decoded from MQA.
I just wanted to warn you before you burn up money and time.
I had planned to start a project with MQA myself, but the implementation with various DACs was not conclusive for me.
My research in forums and mail contact with MQA then confirmed that the DAC chip is also used for rendering by controlling the digital filters.
Therefore, external unfolding is probably not possible, because there would be enough devices with an i2s input.
But that's just based on what MQA said.
I am very interested in what comes out of your project.
I had planned to start a project with MQA myself, but the implementation with various DACs was not conclusive for me.
My research in forums and mail contact with MQA then confirmed that the DAC chip is also used for rendering by controlling the digital filters.
Therefore, external unfolding is probably not possible, because there would be enough devices with an i2s input.
But that's just based on what MQA said.
I am very interested in what comes out of your project.