NEC Network Controller uPD98502 - Manual (Page 313)

CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM 313
6.2.2 U_GMR (USB General Mode Register)
This register is used for setting the operation of USB Controller. The low-order sixteen bits except for RR bit can be
written only when the device is being initialized. If the values of these bits are changed while transmission or reception
is being performed, the operation of USB Controller may become unpredictable.
Bits Field R/W Default Description
31:24 Reserved R/W 0 Reserved for future use. Writes ‘0’s.
23 VT R/W 0 Function Address Valid Timing:
When this bit is set to a ‘1’, FA becomes valid immediately.
When this bit is set to a ‘0’, FA will become valid after USB Controller
receives subsequent ACK packet on EndPoint0.
22:16 FA R/W 0 Function Address:
Register that stores the USB Function Address. This is allocated by the Host
PC as part of the USB configuration process. The V R 4120A should set the
allocated address in this register.
15:8 SOFINTVL R/W 18H SOF Interval:
This value is used to define the allowable skew for SOF packet. The default
value should be 18H. When ‘00H’ is set, the USB Controller does not care
the timing between two consecutive SOF packets.
7:3 Reserved R/W 0 Reserved for future use. Writes ‘0’s.
2 AU R/W 0 Auto Update:
Frame Number auto updating enable. To set to a ‘1’ causes Frame Number
Register to be updated though a received SOF packet is corrupted.
1 LE R/W 0 Loopback Enable:
Bit for enabling internal loopback mode. When this bit is set to a ‘1’, USB
Controller operates in loopback mode. Setting loopback mode enables the
testing of the internal DMA controller. In addition, USB packets are not
transmitted, and USB packets are not received.
For a detailed explanation of loopback mode, see Section 6.9.
0 RR R/W 0 Remote Resume:
When Remote Resume is to be performed, the V R 4120A will set this bit.
Once this bit is set to a ‘1’, USB Controller issues Resume Signaling to the
USB for a period of 5 ms. Upon the completion of Resume Signaling, this bit
is automatically reset to a ‘0’.
6.2.3 U_VER (USB Frame Number/Version Register)
Register that stores the current Frame Number of the USB and version of the USB Controller block.
Bits Field R/W Default Description
31:16 UVER R 0201H USB Version:
Hardwired to ‘0201H’.
The Revision Number of the USB Controller block is stored into this register.
15:11 Reserved R 0 Reserved for future use
10:0 UFNR R 0 USB Frame Number:
Register that stores the Frame Number of the USB.