Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter

[syklab]

Originally Posted by bigpandahk

I am using the same charger as yours but i believe your battery should be LiMH not LiFEPO4.

Hi BigpandaHK,

¡ïʨ×ÓÕýÆ·¡ï¸ß¶Ë LION 7.4V 5200MAH 30C ¾ÛºÏÎï﮵ç³ØBG712-ÌÔ±¦Íø

According to the translation, it is supposed to be Lithium Polymer, their brand is Lion.

[qusp]

not at those charge voltages it isnt LiFePO4, anyway yes Lipo are ok, bit noisy and many packs have switchmode limiting circuit

[bigpandahk]

Originally Posted by hochopeper

was a good suggestion mate!


I want to know what bigpandahk has planned now he's the only guy apart from Ian with more than one of those isol boards!

As I may not require the second isolator board at this stage, I can send it to you then we have one ore tester.

[bigpandahk]

Originally Posted by qusp

not at those charge voltages it isnt LiFePO4, anyway yes Lipo are ok, bit noisy and many packs have switchmode limiting circuit

THat's the reason not buying this kind of battery pad. This is what I am using :
18650 LiFepO4 1800mAh 3.2V

[hochopeper]

Originally Posted by bigpandahk

As I may not require the second isolator board at this stage, I can send it to you then we have one ore tester.

Well, that really is a hard offer to knock back. I would like to hear Ian's thoughts though, it's his to allocate as he wishes IMO.

I don't have a FIFO to use it with yet unfortunately so that is why I'd held out of the testing.

[bigpandahk]

You are right, I should have Ian's consent before making such offer.

[iancanada]

Originally Posted by hochopeper

Well, that really is a hard offer to knock back. I would like to hear Ian's thoughts though, it's his to allocate as he wishes IMO.

I don't have a FIFO to use it with yet unfortunately so that is why I'd held out of the testing.

Originally Posted by bigpandahk

You are right, I should have Ian's consent before making such offer.

Hi guys, I don't have any problem. Go ahead whatever you think it's good.

Ian

[iancanada]

I know a lot of people did this configuration before. I just confirm it by myself once again.

There are three ways hoop up XMOS WaveIO USB interface to FIFO KIT, Please see the attached pictures for details:

1, Connecting the isolated I2S output into the I2S backdoor on the S/PDIF Interface Board. The configuration is highly recommended. But you need an additional Vdd for the isolator. You can feed it with the 5V power supply from J13 on the S/PDIF board.

2, Connecting the isolated S/PDIF output into COX input on the S/PDIF board by a 75ohm coaxial cable.

3, Connecting the isolated I2S output into the FIFO input directly. But please do not use this configuration unless you need only one source from XMOS interface. You can get the isolator power supply from J5 of the FIFO board for this case.

Please never use the un-isolated outputs of the XMOS. PC ground from USB is noisy and not safe enough.

The XMOS WaveIO USB interface sounds great on my system and works perfect with different kinds of player software. To connect it with the FIFO KIT is very easy as well. As a USB based I2S or S/PDIF source, it would be recommended.

Ian

[bigpandahk]

Ian

Is there any way to connect the WaveIO to the TTL input of SPDIF?

[hochopeper]

Ian,

A very interesting post! I am going with WaveIO as my only source at this stage. I was intrigued that you recommended using isolated i2s output between it and the FIFO, even with the isolator between FIFO and clock board. I have powered mine with a lt1085 reg (usb power and ground are connected but not powering anything). Anyway it seems logical to use the isolated output with the way you have written it. I had previously not pursued this option because I had thought FIFO was 3.3V i2s input only, now that you have reminded me that 5V i2s intput can work and FIFO 5V supply output is perfect for this it looks like a great option.

Computer PSU noise can stay on the XMOS side; FIFO fpga noise can stay on the FIFO; and a clean re-clocked low jitter output signal from the clock board. What more could we hope for?! I am pretty excited for the next GB to reach critical numbers!

Also, I know that you check the FIFO for bit-perfect throughput as part of the testing, is there any way to test the whole chain from transport to i2s output? I am not sure how the testing setup for that works so its just me thinking out loud there, though I am 99.999% sure there is not a problem at all.

Cheers,
Chris