Fujitsu Series 3 Manual

 
2. Configuration of USB Function 
 
2.  Configuration of USB Function 
Figure 2-1 shows the block diagram of the USB function 
 USB function block diagram 
Figure 2-1 USB function block diagram 
 
Endpoint 0
IN buffer On-chip bus
UDP
UDM
UDC
CPU 
interface
UDCC register UDCS register
Time stamp
UDC 
interface
USB clock (48MHz)
From USB clock 
generation unit
I/O
Interrupts
Interrupts
Stop signal 
from a device
SUSP
Endpoint 0
OUT buffer
Endpoint 1
Buffer
Endpoint 2Buffer
Endpoint 3
Buffer
Endpoint...

 
3. Operations of USB Function 
 
3.  Operations of USB Function 
The USB function supports the USB (Universal Serial Bus) communication protocol.Its 
hardware supports the basic protocol operation (handshake). Therefore, USB communication 
can be implemented by processing only transfer data. 
 
3.1 USB function operation  
3.2  Detection of connection and disconnection  
3.3  Operation of each register in response to a command  
3.4  Suspend function  
3.5  Wake-up function  
3.6  DMA transfer function...

 
3. Operations of USB Function 
 
3.1.  USB function operation 
To use the USB function, take the following steps for setup. 
1. Configure the USB clock generation unit while th e USB Enable Register (USBEN) disables USB 
operation (USBEN = 0). 
2.  Enable the USB clock output. 
3.  Enable USB operation (USBEN = 1). 
 
The USB function transfers packets bi-directionally to/from a host controller that supports the USB protocol. 
Connection with the host and devices, and configur ation are emulated....

 
3. Operations of USB Function 
 
Figure 3-1 Example USB cable pin connection 
 
  
Operation summary Direction
Operation does not start until the host detects 
USB bus connection 
Host  Device
detection
 pull-up on the USB bus.
Descriptor information 
Returns descriptor data to the host.
Host   Device
acquisition
 
Device address setting 
FUJITSU SEMICONDUCTOR LIMITED 
 
   USB bus connection detection 
The connection is reported from a device to the host. 
The host monitors two signal lines (D+ and...

 
3. Operations of USB Function 
 
 Descriptor acquisition 
When the host requests a device, the device reports data to the host in reply to the request. 
The communication is broken up into the following three stages. 
Figure 3-2 Communication stages 
 
 Setup stage   ->   Data stage   ->   Status stage   
 
The setup stage checks whether the device has received the packets from the host successfully. The 
descriptor information to be returned in the next stage is prepared in the send buffer in this...

 
3. Operations of USB Function 
 
3.2.  Detection of connection and disconnection 
The following explains about detecting connection and disconnection to/from the USB host. 
 Example of USB system connection 
By connecting an external interrupt pin to the VBUS pin of the USB connector, and installing a pull-down 
resistor onto the VBSU signal, disconnection from the USB host can be detected. Figure 3-3 shows an 
example connection of USB c o

nn ector with D+, D- and VBUS. 
Figure 3-3 Example USB...

 
3. Operations of USB Function 
 
 Connection detection 
Figure 3-4 Connection detecting operation 
 
Connected to the host
VBUS ENx
ERx
[LBx, LAx]
HCONX
[0, 1] [0, 0]
Connection enabled
VBUS stables Source level changed
External interrupt enabled
  
 
A device finds and processes the connection with the host in the following sequence: 
1. The HCONX bit in the UDCC register must be set to 1. (When controlling a pull-up resistor on a 
general-purpose port, set the port to the pull-up resistor...

 
3. Operations of USB Function 
 
 Disconnection detection 
Figure 3-5 Connection detecting operation 
 
Disconnected 
from the host
VBUS
ENx
ERx
[LBx, LAx]
HCONX SUSP
USTP Returned from stop mode
[0, 0]
Source level changed
VBUS stabilization 
period or
Oscillation 
stabilization wait time
Disconnection  setting
[0, 1]
  
 
A device finds and processes the disconnection from the host in the following sequence: 
1. Find the disconnection of the USB host by detecting LOW level of the external interrupt...

 
3. Operations of USB Function 
 
3.3.  Operation of each register in response to a command 
The following explains the method (architecture) to process USB packets. Responding to 
CPU interrupts, the firmware sequence is processed for each handshake. This is equivalent to 
the processing of each packet on the stage basis. 
 Operation of each register in response to a read command 
The following explains the case of GetDescripter, SynchFrame, and class vendor commands. 
Figure 3-6 Operation of Each...

 
3. Operations of USB Function 
 
  Command end sequence 
DRQO is set when the status stage  to OUT direction has finished. Immediately when DRQO is set, enter 
the CPU interrupt and check that the number of receive d data units is 0.In preparation for the next setup 
stage, interrupt cause DRQO, and return. 
FUJITSU SEMICONDUCTOR LIMITED 
CHAPTER  20-2: USB Function 
MN706-00002-1v0-E 
1084 
MB9Axxx/MB9Bxxx  Series