Dr. DAC nano

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kibergus
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Dr. DAC nano

Post by kibergus »

I' m experiencing a problem connecting Dr. DAC nano directly to odroid U2 under ubuntu. It just doesn't power up. I see short flashes of optical audio output (normally it is lit all the time) and clicks in speakers. Two flashes with small gap at the beginning then flash every 0.5 seconds. When this happens other devices (a keyboard and a mouse) connected to USB stop working. When I unplug Dr. DAC keyboard works again. In dmesg there are only messages about usb keyboard found after I unplug audio card. There are no messages about devices being disconnected.
The audio card works perfectly when connected via usb hub. It also works fine with odroid X2 on any USB port.

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Re: Dr. DAC nano

Post by mdrjr »

What power supply?

I think that your DAC uses too much current.

Either its hitting the USB limit. Or the amount of current being used is enough to make the power supply drop the voltage.

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Re: Dr. DAC nano

Post by kibergus »

I am using power supply shipped with odroid from your store. Beside that U2 which doesn't work and X2 which work were powered by the same power supply.
I'll try measuring power consumed by the device.

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Re: Dr. DAC nano

Post by kibergus »

I've added ~0.68 Ohm resistance to VBUS and measured voltage drop with a scope. At steady state the card consumes reasonable current about 85mA. But there is big inrush current when it is plugged in. USB hub and X2 allow this current to run for a short period of time and the card works fine.
Odroid U2 immediately throttles current to ~600mA. This causes voltage on VBUS to drop to 2.5 volts (measurement not present on image). Looks like this is not enough for dr dac and it continues to suck power for 19 mS until U2 removes power from VBUS.
Here are the measurements:
glued.png
glued.png (12.86 KiB) Viewed 8634 times
I've set my scope to maximal resolution and it seems that U2 does not allow any inrush current greater than 600mA. I'm not familiar with USB specification, but as far as I understood from rapid googling inrush currents are allowed to be big as long as RC constant of connected circuit is less than 10uF * 44Ohm (I haven't calculated RC constant for dr dac so I don't know if it is in allowed limits).

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Re: Dr. DAC nano

Post by mdrjr »

Well,

First.... AWESOME way to get help.. you just made this man happy today :)

Second. I think that IC/Fuse the deals with current control of the USB port should only handle ~500ma. I'm not sure too about in the in-rush current that it can supply.
I did a quick check on USB reference that I have, and it doesn't say anything about in-rush... it may be out-dated too... It only says 500ma max current.

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Re: Dr. DAC nano

Post by kibergus »

mdrjr wrote:Well,

First.... AWESOME way to get help.. you just made this man happy today :)
:D
mdrjr wrote:Second. I think that IC/Fuse the deals with current control of the USB port should only handle ~500ma. I'm not sure too about in the in-rush current that it can supply.
I did a quick check on USB reference that I have, and it doesn't say anything about in-rush... it may be out-dated too... It only says 500ma max current.
It is covered by section 7.2.4.1 of specification. "Dynamic Attach and Detach"/"Inrush Current Limiting". It is said that hub ports should be equipped with bypass capacitors with capacitance not less than 120uF. If I understand it right, the spikes would be filtered and usb hub itself wouldn't even notice them. So 500ma limitation is not applicable here. But as far as this is the first time I've opened USB specification I'm not sure that I'm right. For example I don't understand how bypass capacitor will help on system startup when all devices are already connected, but capacitor is empty.

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Re: Dr. DAC nano

Post by mdrjr »

It should be always charged, and will discharge when a load > 500ma occours. Still that would create a load > 500ma if the device uses 500ma because the capacitor must be charged again.. Not sure the time that will take to charge..

I'll let the guys from Korea handle this one ;(

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Re: Dr. DAC nano

Post by kibergus »

mdrjr wrote:It should be always charged, and will discharge when a load > 500ma occours. Still that would create a load > 500ma if the device uses 500ma because the capacitor must be charged again.. Not sure the time that will take to charge..
Bypass capacitor is required to be much larger than capacitance of any device. 120uF against 10uF. So when device capacitor would be fully charged voltage on VBUS would drop by less than 5V * (1 - sqrt(120uF/(120uF+10uF))) = 0.2V. And as far as device capacitor is already charged it does not consume much energy any more.
Indeed hub would have to charge bypass capacitor to 5 volts again, but because voltage difference is small, only 0.2V, current would be small too.
mdrjr wrote:I'll let the guys from Korea handle this one ;(
Thanks.

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Re: Dr. DAC nano

Post by odroid »

Can you capture the voltage drop graph when you turn on your odroid while the audio dongle inserted?
I want to see what happen in power up process in whole system.

BTW, the Over-current protection IC specification can be found here.
http://www.ricoh.com/LSI/product_power/ ... ch/r5524n/

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Re: Dr. DAC nano

Post by odroid »

Another possible root cause is U4.
http://www.ti.com/product/bq24381

If the root cause is U4, you may need to bypass it even you lost the system over-current protection feature.
Image

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Re: Dr. DAC nano

Post by kibergus »

odroid wrote:Can you capture the voltage drop graph when you turn on your odroid while the audio dongle inserted?
I want to see what happen in power up process in whole system.
Done. I'll stich, conver them to png and post a bit later.
odroid wrote: BTW, the Over-current protection IC specification can be found here.
http://www.ricoh.com/LSI/product_power/ ... ch/r5524n/
Datasheet mentions 47 uF capacitors on Vout pin (with a footnote that it must be 120 uF). I think they are C221 C220, the only capacitors near U7 and U8. When the board is not powered they should be disconnected by transistor in IC. So I've probed them with multimeter and it shows 6.0uF - 5.8uF for them.

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Re: Dr. DAC nano

Post by kibergus »

Here are the measurements. I've tried plugging the device in-to working odroid and tried switching on odroid with plugged device.
I have uncalibrated DSO quad scope so don't trust absolute measurements. I had to connect ground of both probes to single point on vbus so measured results are inverted. Vbus voltage was measured before resistance I've added to measure current.
glued.png
glued.png (27.61 KiB) Viewed 8553 times

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Re: Dr. DAC nano

Post by odroid »

kibergus wrote: Datasheet mentions 47 uF capacitors on Vout pin (with a footnote that it must be 120 uF). I think they are C221 C220, the only capacitors near U7 and U8. When the board is not powered they should be disconnected by transistor in IC. So I've probed them with multimeter and it shows 6.0uF - 5.8uF for them.
The typical capacitance is 10uF. So it should not enough to supply the inrush current.
I think we have 22uF with the same foot print(form factor) but it is still far from 100uF~150uF to absorb the short time rushing power. :(

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Re: Dr. DAC nano

Post by torqu3e »

You need to do this... http://oomz.net/p/web/IMG_5862.JPG that should solve your issues.

I'll be ordering my U2 by this weekend and have a 100 mhz scope in case you want to know how fast the GPIOs can trip! :D

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Re: Dr. DAC nano

Post by kibergus »

torqu3e wrote:You need to do this... http://oomz.net/p/web/IMG_5862.JPG that should solve your issues.

I'll be ordering my U2 by this weekend and have a 100 mhz scope in case you want to know how fast the GPIOs can trip! :D
I was thinking about it. But I'm afraid that it would solve only hot plugging problem. During boot capacitor would be discharged and would be of no use.

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Re: Dr. DAC nano

Post by moon.linux »

Hi All
I have some Odroid boards which seem to be not working correcly, can somebody share the technique of the software code used to generate or view the voltage graph.

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Re: Dr. DAC nano

Post by mad_ady »

@moon.linux you should start a new thread, not necro-bump one from 2013 :D

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