Hi, I am interested in using a USBHost library with ST Nucleo F401RE and L476RG boards. The official mbed USBHost library does not support these boards. I have tried the library fork developed by a mbed user (https://mbed.org/users/va009039/code/F401RE-USBHost/) and tested his F401RE-USBHostMSD_HelloWorld demo program with a F401RE program. It works as long as you do not update the mbed library. I wanted to try it with the Nucleo L476RG but had to upgrade the mbed lib for this target to be recognized. I then realized that even the F401RE is not working well with this library as soon as you update the mbed lib: No compilation errors, but warning: Warning: Function "mbed::FunctionPointerArg1<R, void>::FunctionPointerArg1(R (*)()) [with R=void]" (declared at <a href="#" onmousedown="mbed_doc_goto('/F401RE-USBHostMSD_HelloWorldUpd_copy6//extras/mbed_9bcdf88f62b0/platform/FunctionPointer.h', '67'); return false;">/extras/mbed_9bcdf88f62b0/platform/FunctionPointer.h:67</a>) was declared deprecated ("FunctionPointer has been replaced by Callback<void()> [since mbed-os-5.1]") in "F401RE-USBHost/USBHost/USBEndpoint.h", Line: 32, Col: 44 Besides, when attaching a USB MSD, I get following message on my debug hyperterminal: "RTC error: LSE clock initialization failed." mbed development team says that this library is currently deprecated. I think that there is a real need for such library support for the Nucleo boards, especially for data I/O to USB MSD. Has anyone ever been facing this kind of need/problem? Could anyone help? Thanks, Regards, Olivier