MKL27: Unknown USB Device

[lore]

Dear experts,

I am experiencing some problems while trying to get my custom MKL27 board recognized to my PC as Mass storage device. It's a fresh new MCU on the board. The device is recognized as follows in the windows device management:

Unknown USB Device (Device Descriptor Request Failed)

What could I be doing wrong? The USB connection is almost identical to FRDM-KL27 board.

Many thanks in advance.

Lore

[bobpaddock]

Is a USB Stack being used or a custom written one?  How was the descriptor created?

See if the Descriptor Dumper sheds any light:

Thesycon USB Descriptor Dumper 

[lore]

Hi Bob, thank you for your reply.

The USB Stack is the factory one.

Unluckily the USB descriptor dumper does not give me any dump information on connected devices. I'm going to apply Mark's suggestions and will be back here hopefully with some updates.

Best regards

Lorenzo

[mjbcswitzerland]

Hi

Do you mean that you are trying to use the ROM loader, which appears as HID device when no code is loaded on the board?

The error message indicates that the USB connection is not operating at all - apart from the fact that the host has seen that the D+ signal has been pulled up to +5V.

Check carefully the exact KL27 device that you are using since they are not all the same. Depending on the exact part it may have an internal USB voltage regulator or it may require an external one. If it has an internal one it is important that it is correctly decoupled otherwise it will also fail.

Regards

Mark

http://www.utasker.com/kinetis/FRDM-KL27Z.html
http://www.utasker.com/kinetis/Capuccino-KL27.html

[lore]

Hi Mark, Thank you for your feedback.

Yes I mean I'm trying to use the ROM bootloader to upload the first code on the MCU.

I will check the decoupling of the VOUT33 internal regulator. Actually I leaved it NC as I'm powering the MCU with external regulator. I looked at your Cappuccino schematics, I will try something similar and let you know.

Best regards

Lorenzo (CH)