Fujitsu MB90335 Series Hardware Manual page 246

MB90335 Series
USB bus connection
detection
Acquiring descriptor
information
Setting device
address
Acquiring descriptor
information (device)
Acquiring descriptor
information
(configuration)
Setting configuration
●
Detecting a connection
The device notifies the host PC.
The host monitors the two signals (D+ and D-) on the USB bus and detects a device connection if either
signal goes to the "H" level.
For the detailed procedure in the case of a self-powered device, see "11.4.1 Detecting Connection and
Disconnection". In the case of a bus-powered device, perform the operation described in "● Example
Register Initialization and Operation Startup Procedure".
●
Example Register Initialization and Operation Startup Procedure
The following is an example of how to initialize the registers and start operation.
1. Set EP0 in the EP0C register (packet size, etc.)
2. Set the EPEN, DIR, and TYPE settings for each EP in the EP1C to EP5C registers.
3. Clear the RST bit in the UDCC register
4. Clear BFINI in the EP0IS, EP0OS, and EP1S to EP5S registers
5. Clear the HCON bit in the UDCC register
●
USB bus reset
A bus reset is applied from the host PC to the device and the USB device core is initialized.
A device must perform processing in the following steps. (The first bus reset after USB has been connected
does not need any processing.)
1. Initializes the USB Function with RST in the UDCC register.
2. Set transmission/receive buffers and related control registers again it will use.
3. Return firmware control to the state prior to enumeration.
CM44-10137-6E
Figure 11.4-1 Connection Example of USB Cable Pin
Direction
Host Device
Host Device
Host Device
Host Device
Host Device
Host Device
FUJITSU MICROELECTRONICS LIMITED
11.4 Operation Explanation of USB Function
Overview of operation
Operation is not started until the host detects
pull-up on the USB bus.
Data of descriptor is returned to the host.
Any address is divided from the host.
Data of descriptor is returned to the host.
Data of descriptor is returned to the host.
Configuration number is divided from the host.
CHAPTER 11 USB FUNCTION
225