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Additional Input and Outpus on 3e Audio ADAU1701 DSP and Aliexpress
Additional Input and Outpus on 3e Audio ADAU1701 DSP and Aliexpress
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Old 21st June 2020, 10:43 PM   #41
kipman725 is offline kipman725  United Kingdom
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Default SPDIF input (48Khz) and external DAC output working

Managed to get this configuration working, output is very clean with the combination of the SPDIF board, burr brown DAC and 3E amp (no background noise). The 3E audios I2S input port is operating as a slave and its output port as a master. The hardware modifications are as follows:
1) Oscilator and one of oscillator capacitors removed from 3E board (see attached)
2) Clock signal from SPDIF board connected to oscillator pads
3) Jumpers J2 and J3 removed

I found out I was incorrect that the clock (MCLK) from the SPDIF board was 24.576 MHz (this is the value of its crystal) its in fact 12.288MHz. I looked into changing the DSPs mode pins for the higher clock frequency but this is not easy as one of them is soldered directly to the ground plane. I then went an built a board with a D-Type flipflop to divide the clock, only to find the clock was too slow and this board was not needed!
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Old 29th June 2020, 11:00 AM   #42
kipman725 is offline kipman725  United Kingdom
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Attempting to integrate the SPDIF and the DSP board into my battery powered sound system project I have been having some issues so have switched to using my spare DSP board and the analog input. The issues are:
1) Sometimes MCLK is 24.576MHz overclocking the DSP board, surprisingly it runs at double frequency. I think this depends on the SPDIF sample rate so when the SPDIF board is powered on at the same time as the DSP there is a period of time with double frequency clock output. The obvious solution to this would be to make sure the SPDIF board powers up first and directly take the 24.576 MHz oscillator into the clock divider I built earlier to clock the DSP.
2) With the SPDIF providing the correct clock I started getting drop outs in the audio output even using the built in DACs. I think this could be ethier due to some kind of EMI beating as I have a lot of free running switch mode circuits in my project that I didn't have just bench testing the DSP and SPDIF or it could be a start up clocking issue as now the SPDIF powers on at the same time as the DSP.

I will see what I can't do with the boards I have but I am getting tempted just to make my own sigma DSP board with exactly what I want on it using the largest part which is only digital in and has ASRC and SPDIF.

Some info on the EEPROM on my 3E board:
ST 24C64RP (64kbit) = 524288 bits (was incorrect in 3E project)
supports upto 1MHz I2C (I have only tried 100 kHz)
32 byte pages, 2 byte addressing
address = a0 (E2, E1, E0 = 0V)
Powered from 3V3 rail
WC = 0 (writes allowed)
I programed it by compile link download to the DSP then right clicking on the DSP in the hardware manager and telling it to send the program to the EPROM.
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Old 29th June 2020, 03:44 PM   #43
mga2009 is offline mga2009
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Quote:
Originally Posted by kipman725 View Post
Attempting to integrate the SPDIF and the DSP board into my battery powered sound system project I have been having some issues so have switched to using my spare DSP board and the analog input. The issues are:
1) Sometimes MCLK is 24.576MHz overclocking the DSP board, surprisingly it runs at double frequency. I think this depends on the SPDIF sample rate so when the SPDIF board is powered on at the same time as the DSP there is a period of time with double frequency clock output. The obvious solution to this would be to make sure the SPDIF board powers up first and directly take the 24.576 MHz oscillator into the clock divider I built earlier to clock the DSP.
2) With the SPDIF providing the correct clock I started getting drop outs in the audio output even using the built in DACs. I think this could be ethier due to some kind of EMI beating as I have a lot of free running switch mode circuits in my project that I didn't have just bench testing the DSP and SPDIF or it could be a start up clocking issue as now the SPDIF powers on at the same time as the DSP.

I will see what I can't do with the boards I have but I am getting tempted just to make my own sigma DSP board with exactly what I want on it using the largest part which is only digital in and has ASRC and SPDIF.

Some info on the EEPROM on my 3E board:
ST 24C64RP (64kbit) = 524288 bits (was incorrect in 3E project)
supports upto 1MHz I2C (I have only tried 100 kHz)
32 byte pages, 2 byte addressing
address = a0 (E2, E1, E0 = 0V)
Powered from 3V3 rail
WC = 0 (writes allowed)
I programed it by compile link download to the DSP then right clicking on the DSP in the hardware manager and telling it to send the program to the EPROM.
Thanks for the info and development kipman

Please keep us posted if you have a breakthrough in adding SPDIF input to our 3E boards. From my part, I am still waiting for my DAC's to arrive, so I can test and report about adding 4 extra outputs to out boards.
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Old 3rd July 2020, 12:26 AM   #44
kipman725 is offline kipman725  United Kingdom
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I have done a lot more fiddling and my conclusion is the SPDIF board is unfortunately never going to work apart from in the limited circumstance that its powered on before hand with a 48Khz input and used the MCLK used to clock the DSP board. (This is the configuration I previously reported as working). Not a super practical configuration.

I had some eventful fiddling blowing up a DSP board and a DAC board in the process. This was because in attempting to debug some intermittent poping noises I tried powering the DSP from a 9-90V to 5V USB power converter. This power converter turned out to be actually referenced to the positive rail and as other circuits where connected to the same power supply that was powering the converter I ended up giving the DAC 55V. Pretty dumb design, good job I have spare parts! (although with the failiure of been able to get the SPDIF board working this now means I have to re-solder the oscillator onto the DSP board).

The final configuration I tried with the SPDIF board was tapping off its 24.576MHz oscillator into my divider to generate the DSP clock. This worked fine, the problems came when I then input the serial audio data lines into the DSP from the DSP. Depending on the sample rate of the SPDIF I got all manner of weird behavior out of the DSP such as sine waves generated on the DSP turning into weird doubled up things or total loss of audio output. Further investigation showed that the serial audio data port on the SPDIF board has no phase synchronization with the oscillator on the SPDIF board. I Guess there is no fifo on the audio data in and the entire DSP processing is somehow slaved to the audio data input. With no suitable stable clock source on the SPDIF board it seems that this has reached a dead end without adding more electronics or reprogramming the SPDIF board or an unacceptably constrained setup!
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Old 4th July 2020, 04:04 PM   #45
kipman725 is offline kipman725  United Kingdom
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I got everything in a box and ran 6 channels of amplification with crossovers into my speakers. Everything is running from the ammo can battery which is a 16S, 20Ah lithium ion. The amplifiers are also 3E audio; TPA3251 which are powered from a buck converter outputting 35V. Idle power consumption is around 18W, I can't get over 20W total power input without it been too loud in my house (100dB/1w speakers). Sounds fine, no background noise unless I put my head in my horns.

Some more info on the DSP; the volume pot is 10k linear taper. Quite hard to remove I had to use hot air.
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Old 4th July 2020, 05:28 PM   #46
mga2009 is offline mga2009
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Quote:
Originally Posted by kipman725 View Post
I got everything in a box and ran 6 channels of amplification with crossovers into my speakers. Everything is running from the ammo can battery which is a 16S, 20Ah lithium ion. The amplifiers are also 3E audio; TPA3251 which are powered from a buck converter outputting 35V. Idle power consumption is around 18W, I can't get over 20W total power input without it been too loud in my house (100dB/1w speakers). Sounds fine, no background noise unless I put my head in my horns.

Some more info on the DSP; the volume pot is 10k linear taper. Quite hard to remove I had to use hot air.
Nice setup!

Thanks for the info on the volume pot. Do you think it's possible to wire 1 volume pot to 2 or 3 3e Audio DSP, so It can control general volume on all dsp's?

Also, reading your last post, you said you were attempting to "debug some intermittent poping noises"... I also have registered some poping noises on the 3Eaudio DSP running my subwoofers. The DSP is powered from a 12volt wall wart and feeds an ICEpower 500ASP. I've tried modifing my SigmaStudio schematics to no avail. Popping sounds are still there, intermittently and I can't find the cause of it. The DSP get the signal from my receivers AVR LFE output, but I am pretty sure the "problem" is the DSP. Any recommendations where I should start looking?
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Old 5th July 2020, 12:46 AM   #47
mga2009 is offline mga2009
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Quote:
Originally Posted by mga2009 View Post
Nice setup!

Thanks for the info on the volume pot. Do you think it's possible to wire 1 volume pot to 2 or 3 3e Audio DSP, so It can control general volume on all dsp's?

Also, reading your last post, you said you were attempting to "debug some intermittent poping noises"... I also have registered some poping noises on the 3Eaudio DSP running my subwoofers. The DSP is powered from a 12volt wall wart and feeds an ICEpower 500ASP. I've tried modifing my SigmaStudio schematics to no avail. Popping sounds are still there, intermittently and I can't find the cause of it. The DSP get the signal from my receivers AVR LFE output, but I am pretty sure the "problem" is the DSP. Any recommendations where I should start looking?
UPDATE: The problem IS the DSP, hardware related or SigmaStudio related, as I tried the ADAU1452 and I did not registered any popping sound.

Tomorrow I will power the 3E DSP with a battery to see if the "popping" is power supply related.
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Old 5th July 2020, 12:46 AM   #48
kipman725 is offline kipman725  United Kingdom
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The volume pot is wired a bit weirdly with the outer pins grounded rather than it been used as a potential divider whereupon you could just wire the same control to multiple DSPs. What I would do is get a multi-gang pot and wire that the DSPs.

The pops I think where caused by the low quality SMPS I was using to step down the battery voltage, I haven't had issues since I switched to using the SMPS built into the TPA3251. You might also want to make sure any unused I2S inputs are totally disabled as my fiddling with the SPDIF showed me that in some ways the DSP is always clocked by the input I2S ports so if there are glitches on unused ports then it will cause issues in the DSP. I'm looking at making a DSP using ADAU1467WBCPZ300 which has has ASRC, SPDIF and AD1937WBSTZ audio CODEC. As a two IC solution it would have a massive increase in capability and still be cheap.
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Old 5th July 2020, 12:57 AM   #49
mga2009 is offline mga2009
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Quote:
Originally Posted by kipman725 View Post
The volume pot is wired a bit weirdly with the outer pins grounded rather than it been used as a potential divider whereupon you could just wire the same control to multiple DSPs. What I would do is get a multi-gang pot and wire that the DSPs.

The pops I think where caused by the low quality SMPS I was using to step down the battery voltage, I haven't had issues since I switched to using the SMPS built into the TPA3251. You might also want to make sure any unused I2S inputs are totally disabled as my fiddling with the SPDIF showed me that in some ways the DSP is always clocked by the input I2S ports so if there are glitches on unused ports then it will cause issues in the DSP. I'm looking at making a DSP using ADAU1467WBCPZ300 which has has ASRC, SPDIF and AD1937WBSTZ audio CODEC. As a two IC solution it would have a massive increase in capability and still be cheap.
Thanks for your reply! Will look for a multi-gang 10k linear pot.

I will disable the I2S as I am not using them for now.. the thing is... How I disable it? hehe.

I attached a pic of the 3E audio "register control".

Cheers
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Old 5th July 2020, 06:03 PM   #50
mga2009 is offline mga2009
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I tested the 3e audio with an USB battery and I did not registered any popping sound, so it might be the wall wart that is failing or something. Good it's not the DSP's hardware.

Also, trying to lower the noise coming from my SW (and looking how to disable I2S input/output) I tried disabling the "Control ADC" which instantly lowered the noise heard when I put my ear very close to my SW's cone. The noise almost disappeared.

So, is it normal that the potentiometers introduce noise? I thought this pots were "all digital" and would not mess with SQ.
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