[SL6087] How to read VPAD-USB status with AT command


#1

Hi,

Is there any way to read VPAD-USB state with AT command ?

I have a problem with USB that is not answered in other topic. Maybe here :

I use my own board with embedded linux 2.6.21.
SL6087 Firmware version is:R7.43.0.A1
SL6087 is in default fast idle mode.
D- is always near 0 V

I don’t see SL6087 enumeration in system. I also can’t see any transfer on D+,D- pins. It seems like SL6087 is not detected.
I can enable USB with
AT+WMFM=0,1,3
D+ goes to 0,09 V

AT+WMFM=0,0,3
D+ shrinks to 0,01 V

  1. Are those Values correct - D+ seems to low for me ?
  2. How can I check if VPAD-USB is HIgh ? (How to read this input)
  3. Are there any other AT commends to check USB state

Thank you for your answers,
Bartlomiej Grzeskowiak


#2

If you refer the PTS of SL6087, you can see that the minimum voltage listed for USB-DP and USB-DM is 3 v. I guess because your SL6087 is not enumerated in the system ,the value of D+ is low .

You may have to measure the voltage at the VPAD-USB pin .There is
no specific AT command to read the state of this pin .

AT+WMFM ? command would give you the state of the USB i.e. if it is disabled or enabled .Also to see why the device is not enumerated, you can try looking into the sys logs.