MK20DX128VFM5: USB CDC device not enumerating

[huishao2]

Hi-

I have problem to make my board enumerated after plugging USB connector into Windows PC. Windows shows nothing after a connection. My configuration is like:

OS: MQX 4.1.1

HW: MX20DX128VFM5

Tool: IAR and I-jet

BSP: k20d50m

My costumed board is driven by 8MHz crystal and +5v comes directly from PC USB port. The USB ID detection pin is tied to ground and +5V power is seen on the board after connecting to PC. After calculation my board should supply 48MHz to ARM core.

HW wise, how can I debug this issue? I have also post same question on MQX forum(MQX 4.1: USB CDC device "virtual com" not enumerating).

I am asking here to see if I can get HW people help on it.

Thanks!

Hui

[huishao2]

It ends up a mistake I made. The COM port had shown up under Ports of Windows Device Manager which was overlooked. The reason windows doesn't show anything when CDC device is attached is because the inf file had been installed for previous project.

Another question got raised, even though the enumeration is done successfully with a PC, the CDC device failed to enumerate with a k20d76m based host. However, that host is able to recognize a commercial USB CDC device and finish data communication. What could be the cause?

Thanks!

Hui