6 tx indication – NEC Network Controller uPD98502 User Manual
Page 343
CHAPTER 6 USB CONTROLLER
Preliminary User’s Manual S15543EJ1V0UM
343
6.5.6 Tx indication
For every data segment to be transmitted, USB Controller writes a Tx indication into the Tx MailBox. After writing a
Tx indication, USB Controller sets the transmit completion bit of USB General Status Register1 to 1 and, provided it is
not masked, issues an interrupt to the V
R
4120A.
The format of the transmit indication is as shown below.
Figure 6-11. Transmit Indication Format
31
15
EPN
0
Reserved
16
1
2
Status
7
8
Reserved
10
11
3
Status: Field that indicates the status upon data transmitting.
Bit10: When set to a ‘0’, indicates that an IBUS error has not occurred.
When set to a ‘1’, indicates that processing is terminated abnormally due to an IBUS error.
Bit9:
When set to a ‘0’, indicates that a buffer underrun did not occur during data transmitting.
When set to a ‘1’, indicates that a buffer underrun occurred.
This bit is set only when transmitting data to EndPoint1.
Bit8:
When set to a ‘0’, data transmitting is performed in SZLP mode.
When set to a ‘1’, data transmitting is performed in NZLP mode.
For EndPoint0 and EndPoint5, this bit is usually set to a ‘1’.
EPN:
Field that indicates the EndPoint number.
000:
EndPoint0
010:
EndPoint1
100:
EndPoint3
110:
EndPoint5