How do I program a BULK IN transfer with the MAX3420E?

When you have data ready to send to the host, load an IN FIFO, then write the byte count register for the particular endpoint. Since the IN FIFOs are 64 bytes in length, up to 64 bytes can be loaded at a time. When finished loading the data, write the IN endpoint BYTECOUNT register with the number of bytes loaded into the IN FIFO. Writing the byte count register "arms" the endpoint for USB transfer. The MAX3420E does the rest. The next IN request to its device address and the armed endpoint sends the FIFO data to the host.