We have a custom board with a Kinetis MK60DN512VLQ10 running an MQX 4.0.0 application.
Our application uses the USB HostMSC feature with the MFS library. We tested several different USB mass storage devices successfully.
Now we have a series of 8GB devices which SOMETIMES do not enumerate.
When the enumeration fails, the following sequence happens: We get a bus timeout in the setup phase of the first control transfer (get device descriptor). The USB Host driver (MQX KHCI low lever driver) retries and emits the token 15 times (NAK_COUNT) and gets bus-timeout (PID 0x00) repeatedly. When the device is unplugged and plugged in again, then it is sometimes enumerated and sometimes not. Once the device is enumerated, the MSC class driver and the MFS driver work with no problems!
Has anyone seen this before or has any ideas where to search for the solution?