Fujitsu MB90335 Series Hardware Manual page 247

CHAPTER 11 USB FUNCTION
11.4 Operation Explanation of USB Function
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Getting descriptor
The device receives a request from the host PC and sends data to the host.
In more detail, communications are performed in the following three stages:
The setup stage ensures that the device receives normal packets from the host PC and identify the command
by decoding it. In addition, the next data stage prepares information on a descriptor to be sent back in a
transmission buffer. The data stage simply confirms that normal data is sent from the host PC. The status
stage performs end processing when the host PC sends a packet without data.
226
Figure 11.4-2 Communication Stage
→
Setup stage data stage
FUJITSU MICROELECTRONICS LIMITED
MB90335 Series
→ status stage
CM44-10137-6E