I'm using the LPCXpresso54608 SDK for MCUXpresso. In particular, I'm running the generic HID device with FreeRTOS example code (link to my code/setup).
The purpose of the code is to echo data sent from a PC program back to the PC. This all works as intended, but now I'm trying to modify it for my specific application needs.
In the function "USB_DeviceHidGenericCallback", the switch/case called after receiving a USB message includes a call to "USB_DeviceHidSend" which performs the echo function ... so far so good. After that, within the same switch/case "USB_DeviceHidRecv" which eventually calls "USB_DeviceLpc3511IpRecv" which is the device specific call for the LPCXpresso54608 development board ... again, so far so good. But then, within "USB_DeviceLpc3511IpRecv", the only function is to call "USB_DeviceLpc3511IpSend".
usb_status_t USB_DeviceLpc3511IpRecv(usb_device_controller_handle controllerHandle,
return USB_DeviceLpc3511IpSend(controllerHandle, endpointAddress, buffer, length);
// Example code echo data??? NBG
// return kStatus_USB_Success;
My initial thought was that this was simply an accidental redundant means of echoing the received data, but when it is called, no data is received by the PC. I attempted to replace the call with a return of the enumerated value for a successful USB operation, but then the ENTIRE PROGRAM STOPPED FUNCTIONING AND I HAVE NO IDEA WHY!!!
If anyone knows what the purpose is for the send within the receive shown above, please let me know.
Thank you in advance!