Fujitsu Series 3 Manual

 
3. Operations of USB Function 
 
 Operation of each register in  response to a write command 
The following explains the case of Se tDescripter and class vendor commands. 
Figure 3-7 Operation of Each Register in Response to a write Command 
 
  
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  Setup sequence 
Upon the receipt of the setup stage, DRQO change s to 1. Immediately when DRQO has changed to 
1, enter the CPU interrupt and ch eck the SETP flag. If the flag is 1, read required bits of the 
command in the...

 
3. Operations of USB Function 
 
3.4. Suspend function 
Depending on the bus power configuration, USB devices must drop the power consumption to 
500 A or less in suspend state. The following explains the sequence a device makes 
transition to suspend state, and then stop mode or timer mode. 
  Suspend sequence 
When the USB device core detects a suspend state, SUSP in the UDCS is enabled. 
The following provides  an example sequence. 
Figure 3-8 Suspend operation 
 
  
Suspend state 
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3. Operations of USB Function 
 
3.5. Wake-up function 
To recover a USB device from suspend state to wake-up state, the USB protocol provides two 
ways. 
- Remote wake-up from the device 
- Wake-up from the host 
 Remote wake-up 
Figure 3-9 Remote wake-up operation 
 
  
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The device must be processed  in the following sequence: 
1.  Recover the device from stop mode or timer mode by an external interrupt. 
2.  Check that the USB generation clock is stable. 
3.  Clear...

 
3. Operations of USB Function 
 
 Wake-up from the host 
Figure 3-10 Wake-up operation from the host 
 
  
Suspend state
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Process the USB device in the following sequence. 
1. Set the oscillation stabilization time so that it will not exceeds 10 ms. 
2.  Check that the USB clock is stable. 
3.  Clear SUSP in the UDCS regi ster, and USTP in the UDCC register in this order. 
4.  Clear WKUP in the UDCS register. 
 
STP 
1ms 1ms
20 ms or more 
SOF SOF
WKUP 
RESUMEHost ...

 
3. Operations of USB Function 
 
3.6.  DMA transfer function 
Data handled by the USB function can be transferred via DMA between the send/receive 
buffer and internal RAM. The following two modes are available for the DMA transfer. 
- Packet transfer mode that transfers each packet according to the configured data size   
- Automatic data size transfer mode that transfers the configured data size by a single 
transfer. 
 Packet transfer mode 
The packet transfer mode transfers each packet accord ing...

 
3. Operations of USB Function 
 
 Transfer in the IN direction (Host -> Device) 
Figure 3-12 IN packet transfer 
 
  
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In the IN direction transfer, the device mu st be processed in the following sequence: 
1.  Once the DRQ flag is set and the interrupt handlin g is entered, configure the DMA register settings 
relevant to the number of transfers and block size corresponding to the data size to be transferred in 
the next IN packet, and then enable DMA to start the...

 
3. Operations of USB Function 
 
 Automatic data size transfer mode 
This mode can transfer even bytes. To transfer od d bytes, a CPU transfer sequence is required. (See  Figure 
3-14 ) Before using DMA, set 
the interrupt output destination by the DREQ Select Register.(Connect the 
interrupt  ou

tput to DMAC.) For details, see Chapter DMAC.Configure in DMA the total data size to 
transfer, and also set the transfer enable bit previous ly.If DRQ is set after transfer from the host while 
DMAE is...

 
3. Operations of USB Function 
 
Figure 3-14 Example odd bytes transfer in the OUT direction   
 
150 150
To transfer the last data via the CPU
EPxDTH/SPxDTL
DMA 
transfer
(Read)
15 0 15
0
11H(1st byte)
The data is discarded
To transfer all data via DMA
EPxDTH/SPxDTL Undefined
Transfer EPxDTL data via CPU (Read)
33H(3rd byte)
55
H(5th byte)
77
H(7th byte)99
H(9th byte)
22
H(2nd byte)
44
H(4th byte)
66
H(6th byte)
88
H(8th byte)
DMA 
transfer
(Read)
11H(1st byte)
Undefined
33H(3rd byte) 55
H(5th byte)...

 
3. Operations of USB Function 
 
 Transfer in the IN direction (Host -> Device) 
Figure 3-15 Transfer in the IN direction (Device -> Host) 
 
  
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In the IN direction transfer, the device mu st be processed in the following sequence: 
1.  Configure the DMA register setting relevant to the number of transfers and block size corresponding 
to the total data size, and then enable DMA to start the transfer. 
2.  Enable DMAE and DRQIE. 
3.  After the transfer, reconfigure...

 
3. Operations of USB Function 
 
3.7.  NULL transfer function 
If data sent from the USB function is the last packet and satisfies the maximum packet size, 
then the 0-byte can be automatically transferred via the next packet transfer. DMAE must be 
enabled to use this function. This function is valid only in IN transfer. 
  NULL transfer mode 
NULL transfer mode sends 0-byte in reply to the next ho sts data request in the IN direction after the last 
data in the IN direction has been transferred....