Spark core usb host

[ScruffR]

Yes there is
I think it's in @kennethlimcp 's Dropbox - Porting Arduino Serial (PS2) Keyboard Library - #13 by kennethlimcp - Libraries - Particle

I've once used the PS/2 capability of a USB mouse to make a prank mouse (but also useful for real world applications) which also listened to Bluetooth commands (mouse movement and keyboard presses ;-)) - quite alarming for unaware users - hihihi

@ScruffR

I did this a while ago with a USB mouse and a Teensy

vKeyboardMouse_BTA modded Logitech mouse that sends it's PS/2 data stream to the Teensy which normally forwards it as USB-HID-Mouse package. This way it normally behaves like an ordinary mouse. But via a Bluetooth-SPP connection you can alter the normal mouse behaviour or even send Keyboard-/Mouse-HID-Packets/-Macros from any BT device to the mouse, which then forwards them to the host.

This is also a reason why I'm eagerly looking forward to the next evolution of the feature/usb_hid_support from @satishgn to allow for composite USB HID mouse/keyboard/serial/...