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How does one receive LED states in USB keyboard

Question asked by Jan Danielsson on Mar 17, 2018
Latest reply on Mar 22, 2018 by Jan Danielsson

I'm using SDK 2 (2.3.0, specifically), and I've modded the composite keyboard and mouse example to create a PS/2-to-USB-adapter. Sending key events from the PS/2 keyboard via the MCU to the PC works great, but how does one go about receiving LED states sent from the operating system?  (I have written the code to set the LEDs on the PS/2 keyboard, I just need to figure out how to receive the LED states from the PC via the USB stack in the MCU).


I added some debug outputs to the USB_DeviceHidKeyboardCallback() function and noted that each time I press any of the keys which would normally toggle any of the LEDs, I get a kUSB_DeviceHidEventRequestReportBuffer event, so my guess it has something to do with that.


Reading the USB HID 1.11 reference I get a vague feeling that the composite example is missing something like an "out endpoint"? g_UsbDeviceHidKeyboardEndpoints only declares an USB_IN entry, and I was wondering if there needed to be an USB_OUT entry to receive codes? Then again, it looks like I'm getting a relevant event?