In Full Chip Simulation (FCS) mode, this module simulates all functionality of the Universal Serial Bus (USB) module including USB flags and interrupts, seven USB endpoints, USB RAM and USB reset options. While all control transactions occur through bi-directional endpoint 0, the other endpoints can be set up for data transfer in the input or output direction.
Some of the microcontrollers in the HCS08 family contain USB compliant peripheral devices. These can be low-speed or high-speed USB slave devices. This means that all USB transfers are initiated by a host (i.e. a personal computer) and that the microcontroller needs to be set up to respond with the appropriate acknowledgement messages. According to the USB specification, there are a series of messages that go back and forth between the host and the device in order to set up and describe the channel for data transfer. All of these messages can be set up through the USB I/O commands built into the simulator. This section goes through an example of this, showing how the simulator can be used to test out code for driving the USB peripheral.