Below is a support request received. We'll run through this in the forum so there is a searchable record of this for future reference.
We’ve purchased the LPC1768 mbed unit and using the enclosed USB cable
plugged it into a PC running winXP.
But we’re not getting acknowledgement from winXP that a device is
plugged in!
I’ve changed the cable, and used the cable that came with the unit on
another USB device and that worked ok.
Any thoughts?
Ps. I’ve measured the voltage going into the unit (USB) at 4.75V and
seen the 3v3 on Vout and VB.
A few things we should work through to see where the issue might be:
1) When the board is plugged in, does the status LED light up? This is more than a power LED, it is lit under software control, so will suggest if the interface is trying to do something.
2) When you plug the mbed microcontroller into your PC, assuming the LED lights initially, does it flicker at all This would suggest it is trying to enumerate. Also, does it switch off when you hold the reset button down?
3) Can you try the board on a few PCs, just to rule out there being any strange issue with this one secific machine.
4) Was the board shipped in foam? If so, can you remove it from the foam. It should be okay but we have seen issues before with a conductive foam preventing USB enumeration (by shorting out the USB pins!)
Thanks,
Chris
Simon Ford.
1 reply
Below is a support request received. We'll run through this in the forum so there is a searchable record of this for future reference.
A few things we should work through to see where the issue might be:
1) When the board is plugged in, does the status LED light up? This is more than a power LED, it is lit under software control, so will suggest if the interface is trying to do something.
2) When you plug the mbed microcontroller into your PC, assuming the LED lights initially, does it flicker at all This would suggest it is trying to enumerate. Also, does it switch off when you hold the reset button down?
3) Can you try the board on a few PCs, just to rule out there being any strange issue with this one secific machine.
4) Was the board shipped in foam? If so, can you remove it from the foam. It should be okay but we have seen issues before with a conductive foam preventing USB enumeration (by shorting out the USB pins!)
Thanks,
Chris