Robin2, In addition to learning more I do have a project in mind.
Originally, I wanted to replace a radio control transmitter and receiver with some Arduino hardware and a couple of the RFM67 modules (maybe I dont have he number correctg). I wanted to use a USB game controller as the user control. I have the rf link working. I have the PWM modulator working. However, I am frustrated to the point of dumping the USB shnield and a game controller. It seems that the USB library only works with specific devices and I do not know what they are and I cannot continue to buy one from Amazon, try it, see that it doesn't work, and then return it. I have done this three times so far. So, I have decided to purchase some of the joystick assemblies and then use the ADC's on the Arduino to read their position and then send the position to the remote Arduino via the RF link.
I have this joystick controller from a RC simulator that has a funny USB connector. It has the USB connector along with another IC. Ah Ha, I figured, this is a FTDI cable. I took apart the connector expecting to find a serial interface, RS232 type as a baud rate to be determined, but instead found out that it was a PWM signal. The adapter by the USB connector converts PWM to USB.
I was hoping that I could cut off the USB connector and adapter and use the box as a serial interface. Then I began to wonder how the Arduino USB connector related to a baud rate of the serial monitor. I guess if I have an assembly of joystick and buttons connected to another (perhaps) arduino that converted the switches and voltages from the joysticks to serial data I could connect it to the USB connector of the Arduino. However, it seems I will have to use pins 0 and 1 instead.
Anyway, I am still considering my options. A serial game controller would be nice but they are not available.