Two weeks ago, my xM C worked fine. But recently, I got stuck with usb port connection. After reboot, the usb connection doesn’t work sometimes. even if it works, the connection will be lost after a while. I can not figure out SW problem. Now I check the usb hub power. I found D14 green light, usb hub power indicator is on if usb connection is fine after reboot. After a while, when linux kernel emits message and usb unregisters by itself. D14 goes off gradually. I measured the pin 2 (DV_5V_USB) of U16 (TL1963A), it reads 1.47v. When D14 is on, it is 4.97v. I don’t think DV_5V_USB is controlled by SW. I guess the USB power supply circuitry has fault. I have no info in this part. Can anyone help me out or give me a clue?
First thing to check is your +5 V supply for the BB. If you’ve attached a new device, the new current drain could pull down the +5 if you don’t have a good supply and cable. Once I discovered that the USB cable I was using to supply +5 had unexpectedly high resistance, leading to trouble.
I have checked 5V power supply. It is always 5V. In terms of symptom, it seems it could be to do with capacitor. there are four 100 uF capacitors around U13 which also uses DV_5V_USB.
the max current of my power supply is 2.5 A. Even if I don’t plugin anything in usb port or ethernet, D14 is not on most time, in this case, no usb or ethernet device is detected.
The polarity of this rail changed in the rev C vs. the Rev B. If you have old SW it may end up turning this rail off instead of turning it on. Use the image that ships with the board and confirm that it works.
The polarity of this rail changed in the rev C vs. the Rev B. If you have old SW it may end up turning this rail off instead of turning it on. Use the image that ships with the board and confirm that it works.
Gerald
Hi Gerald,
Yes, I tested it. It has same problem. Why must it be turned off? If it is turned off, that means no power on usb hub. I see if it is off, usb does unregister by itself. I noticed SW patch enable xM C usb host power by low. I measured U32 pin6, it is low, that enables usb host power from main 5V power.
It must be turned off to save power. In a power down mode shutting those devcies off saves power. We also has an issue where if running from the USB power some PCs cold not handle the added power draw. So, we set it to come up off, allowing theSW to decide when to turn it on. Older SW used the previou spolarty where it came up on
It must be turned off to save power. In a power down mode shutting those devcies off saves power. We also has an issue where if running from the USB power some PCs cold not handle the added power draw. So, we set it to come up off, allowing theSW to decide when to turn it on. Older SW used the previou spolarty where it came up on
Gerald
If usb hub power is turned off on boot, how possible is it to detect usb device by kernel? I got a replacement for my xM rev.c from the distributor. It has no usb power problem. The new BB usb power light is turned on a second after boot using attached SD card. A C1 label on it. Any update from XM C? Where can I get the configuration of the kernel coming with the BB?