This topic provides a brief overview about USB bulk transfers. I have for a long time been wanting to do a Custom USB class driver on the RT106x devices.Each USB transfer is one packet, which can be up to 64 bytes if using bulk type. If you want to send more than 64 bytes, you have to use multiple packets. In my receive callback, after each packet received, it increments the address for the new packet, and at the end of the transfer it swap the buffers. For bulk transactions, the maximum packet size is 64 bytes for full speed. This is actually per USB spec. In this topic, you'll learn about a USB bulk transfer and how to initiate a transfer request from your UWP app that communicates with a USB device. I am trying to communicate between PC and uC using Labview USB RAW. I have successfully read and write data in interrupt method.