I have a custom board based on i.mx6ul and have problem in using Mfgtool2.exe to download firmware on to i.mx6ul ram through i.mx6ul OTG USB port from PC. The board is configured in serial downloader mode. A USB cable is used to connect between PC and i.Mx OTG port (USB_OTG_D+, USB_OTG_D-, USB_OTG_ID pins). When pulling USB_OTG_ID pin high, PC detects an unknown USB device, but failed in finding and installing USB device driver.
Can anybody help? I assume that the OTG USB port should be configured as device not a host for this case. Are there any specific requirements on the OTG USB cable, such as 90 Ω differential line impedance? Does NXP provide USB driver?