USB-Audio Platform Power Problem

[xaerox]

Hello everybody,
I have another question(s).

1.) I notice, that the USB-Audio Device based on the XMOS Multichannel Audio Platform schematics will frequently restart. That means, the device seems like to restart/reboot again and again. It's horrible to see the computer saying: device connected, device removed...
The device is powered using the USB-Port power (5V). I already the power consumption of this device: about 350-400 mA. Is it possible, that the computer haves not enough power for this device?

2.) Something like the problem above: I want to reduce the power consumption of my device. I actually use the Audio-components (ADC, DAC, some LEDs). No ADAT, SPDIF, MIDI or anything else (also deactivated in Software). Is it possible to minimize the power consumption in Software-Base? Which Cores needs most of power?

I would be glad, if you can help me.

Kind Regards,
Thomas

[infiniteimprobability]

It's horrible to see the computer saying: device connected, device removed...
The device is powered using the USB-Port power (5V). I already the power consumption of this device: about 350-400 mA. Is it possible, that the computer haves not enough power for this device?

Possibly. Have you measured the bus voltage during these issues? If it goes below about 4.4V then the comparator in the PHY will not see a valid USB host voltage.

The power draw seems pretty high (almost 2000mW). Even when running flat out, I would not expect a dual tile device to be drawing more than about 500mW when running USB audio. Where is the rest going!?

Something like the problem above: I want to reduce the power consumption of my device. I actually use the Audio-components (ADC, DAC, some LEDs). No ADAT, SPDIF, MIDI or anything else (also deactivated in Software). Is it possible to minimize the power consumption in Software-Base? Which Cores needs most of power?

It is, but not by a huge amount. Most of the power goes in to XUD which is the USB device library. Then there's the PHY which uses what is uses due to the current sources http://www.usbmadesimple.co.uk/ums_6.ht ... ansmission. We have seen moderate power savings from defining CHAN_BUFF_CTRL which changes a poll to an event. You can also consider slowing down the clock on the second tile. You could also wind the core power down going for 0.95V on the core rather than 1.0V. Compiling with dual issue off and -Os can sometimes save a small amount too.

However, these all save a bit here and there and I wouldn't expect to save more than about 20% of the chip power. I think it's worth finding where the other 1.5W is going..

[xaerox]

Hi infiniteimprobability,
I used a laboratory power-supply to measure the power consumption of the device.
I read a little bit on the Wikipedia-Page which gave following informations:
USB 2.0
4,40 V to 5,50 V Low-Powered-Port (100 mA)
4,75 V to 5,50 V High-Powered-Port (500 mA)
4,45 V to 5,50 V USB-3.0-Port (900 mA)
So I used the High Powered-Port on my computer (500 mA).
Maybe I can try to use an USB-3.0 Port or USB-HUB which gives me 2000 mA.
Another Idea is to use an Y-adaptor to get more power by using 2 High-Powered Ports.

Thank you for your informations. I will try to reduce the power consumption with your tipps.

Kind Regards,
Thomas