USB bootloader on LPC11U37 is failing

[callan_kevin]

I have an LPC11U37 design. Some boards will enter ISP mode and mount as a USB drive on the Windows XP box and some will not. I took three of the failing units and verified that each processor has 3.3V power, each has the ISP signal low on power up, each has USB VBUS high (4.7V). The USB connector and solder joints look good for all units. Two of the units have a working clock oscillator and one does not. I've rejected that one as a different problem. What can keep some parts from mounting as a USB device to accept a new image?

[jeremyzhou]

Hi Kevin Callan,

Thank you for your interest in NXP Semiconductor products and
for the opportunity to serve you.
Whether these two LPC11U37 units be able to be programmed and debugged. And accord to your statement, the hardware circuit seems to be correct, I'd like to suggest you use the attached tool to trace the process of USB enumeration, it may provide us the more information about the issue, so please give a try.
Have a great day,
TIC

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[callan_kevin]

Using the software you provided, this is what happens when we connect one of the failing boards. This looks the same as if we I had plugged in the board without pressing the ISP button.

[jeremyzhou]

Hi Kevin Callan,

Thanks for your reply.
Obviously, the LPC11U37 doesn't enter the ISP USB mode, and I'm curious about whether the LPC11U37 execute the application or not.
In further, how about the ISP UART mode, can these devices enter this mode successfully?

Have a great day,
TIC

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Note:
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- We are following threads for 7 weeks after the last post, later replies are ignored
Please open a new thread and refer to the closed one, if you have a related question at a later point in time.
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