When I use a board with 3014,no matter the Pmode set to F1F or F11,the USB control center can find the "Cypress USB Bootloader" and I can download the firmware to the ram,But when I use a board with 3012 and set the Pmode to F11,the USB control center can find nothing,then I change the Pmode to F1F, the USB control center can find "Cypress USB Bootloader"and I can find the VID/PID=04b4/00f3,but when I try to download firmware to ram of 3012 ,the control center give a message:bootloader is not running,please reset your device to download firmwire.when I reset the device with control center,The problem is still not gone.Another difference of the two FX3 is power.the board with 3014 is powered with Vbus of USB.the board with 3012 is power by other external power。
Have a look at this datasheet:
Go to 'Errata' on page 47:
2. USB enumeration failure in USB boot mode when FX3 is self-powered.
■ Problem Definition FX3 device may not enumerate in USB boot mode when it is self-powered. The bootloader is designed for bus power mode. It does not make use of the VBUS pin on the USB connector to detect the USB connection and expect that USB bus is connected to host if it is powered. If FX3 is not already connected to the USB host when it is powered, then it enters into low-power mode and does not wake up when connected to USB host.