Hello, I'm developing a branch of firmware for a device that will allow data to be streamed using the USB interface that 's part of my platform, the KL27Z. It is my understanding that USB is no longer officially supported as of mbed 5 (the version I am using). I am trying to use USBSerial, I almost have it working, but I'm seeing a strange issue. When connected, the device appears as an HID device called "Kinetis Bootloader". So some part of the USB stack is functioning. But I haven't been able to send/receive any data from the device. Additionally, it looks like mbed is never reaching my main function. None of my breakpoints are working and when paused the program is always executing in a code region with no source available. Does anyone have any idea what could be causing this hang or how I could go about locating the cause of the bug? Thanks!