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Old 15th November 2012, 08:23 AM   #781
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^ What they said plus check the series resistor values on the board. For twisted pair they should be circa 70-90ohm (plus source resistance of the driver) to match the Ethernet's 100ohm impedance.
The better way is to use proper differential signaling techique - whether it's use of bare LVDS or transformer coupled (as used in Ethernet).
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Old 15th November 2012, 08:24 AM   #782
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Quote:
Originally Posted by Hercules View Post
It took me 15 mins to rewire them, as it's all solid core, need a tweezers to hold the wire, as the RJ45 socket is PCB type, quite hard to avoid short of wires.
Have you seen your pcb & clock are broken?
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Old 15th November 2012, 08:28 AM   #783
syklab is online now syklab  Hong Kong
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That looks like left overs from the glue gun only.
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Old 15th November 2012, 08:37 AM   #784
syklab is online now syklab  Hong Kong
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Quote:
Originally Posted by s3tup View Post
^ What they said plus check the series resistor values on the board. For twisted pair they should be circa 70-90ohm (plus source resistance of the driver) to match the Ethernet's 100ohm impedance.
The better way is to use proper differential signaling techique - whether it's use of bare LVDS or transformer coupled (as used in Ethernet).
Hi,
How do you turn the data, Bclk and Frame sync SE signal into differential signal?

Thanks
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Old 15th November 2012, 08:39 AM   #785
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Originally Posted by syklab View Post
That looks like left overs from the glue gun only.
Sorry confused me.
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Old 15th November 2012, 08:49 AM   #786
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Default I2S Grounding Questions

Please comment:

1. If I use a 3.3V to 5V I2S buffer, I don't physically attach those the ground wires to the signal wires do I? If not, where would the ground wires run?

2. On my DAC board there's only BCK, DATA, and FS. The nearest grounding point on the DAC board is 5 inches away.

Thanks
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Old 15th November 2012, 08:52 AM   #787
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Quote:
Originally Posted by crobbins5421 View Post
Please comment:

1. If I use a 3.3V to 5V I2S buffer, I don't physically attach those the ground wires to the signal wires do I? If not, where would the ground wires run?

2. On my DAC board there's only BCK, DATA, and FS. The nearest grounding point on the DAC board is 5 inches away.

Thanks
I don't understand what you're suggesting in your 1st question.

For your 2nd question, if you must use that DAC, then the best alternative is to scrape some soldermask off and expose some of the copper from the ground plane.
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Old 15th November 2012, 08:56 AM   #788
syklab is online now syklab  Hong Kong
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I also face similar issue with my dac, I will need to drill a small hole and scrape off the soldermask at the bottom layer of the PCB where the ground plane is.
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Old 15th November 2012, 09:15 AM   #789
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I use the TDA1541A chip in my DAC. It uses 5V logic.

To use the Amanero board, I need a 3.3V to 5V level shifter like this:

So...I just run the I2S sigal grounds to the power ground on the level shifter?

Also, shouldn't the signal wires be the same length as the ground wires?...
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Old 15th November 2012, 11:26 AM   #790
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Quote:
Originally Posted by syklab View Post
Hi,
How do you turn the data, Bclk and Frame sync SE signal into differential signal?

Thanks
Use the RS-485 or LVDS transmitter/receiver ICs...



For level shifting you could use TTL-compatible CMOS ICs such as HCT series.

Throw-in a reclocker near the DAC which will reclock data, BCLK, LRCLK lines with MCLK clock. Make the MCLK connection the best you can.

But TDA1541 doesn't require 5V level logic signaling - it's kinda weird as per HtP/ecdesign threads. Use these attenuators recalculated for 3v signaling and be happy, or use the 3v directly.
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