You're probably asking about using a Propeller as a USB host. You can't really do it. There are some devices like the Vinculum chip used in Parallax's Memory Stick Datalogger that act as a USB host for some devices (HID {joysticks, keyboards, mice, etc.} and memory) and a Propeller can be used to control these.
There was some experimental code for using a Propeller as a USB host for HID, but it cheated and doesn't conform to the USB standards, so it doesn't really count.
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You're probably asking about using a Propeller as a USB host. You can't really do it. There are some devices like the Vinculum chip used in Parallax's Memory Stick Datalogger that act as a USB host for some devices (HID {joysticks, keyboards, mice, etc.} and memory) and a Propeller can be used to control these.
There was some experimental code for using a Propeller as a USB host for HID, but it cheated and doesn't conform to the USB standards, so it doesn't really count.