![](http://datasheet.mmic.net.cn/380000/-PD98501_datasheet_16745028/-PD98501_434.png)
CHAPTER 6 USB CONTROLLER
434
Preliminary User’s Manual S14767EJ1V0UM00
6.6.7 Detection of errors on USB
USB Controller has some functions which detect some errors on the USB.
Errors shown in figure below are related to Isochronous EndPoint and SOF packet.
Figure 6-23. USB Timing Errors
SOF
SOF
ISO.
ISO.
SOF
ISO.
SOF
ISO.
SOF
ISO.
Correct
Loss of
Data
Loss of
SOF
Extra
Data
Extra
SOF
Error
Error
Error
Error
(1) If “Loss of Data” error has occurred, EP2ND bit (Bit 5) in USB General Status Register2 will be set. The other
action of USB Controller for this error is explained in next section (Section 6.6.8).
(2) If “Loss of SOF” error has occurred, SL bit (Bit 0) in USB General Status Register2 will be set.
In this case, USB Controller only reflect the error to USB General Status Register.
(3) If “Extra Data” error has occurred, EP2ED bit (Bit 6) in USB General Status Register2 will be set.
In this case, USB Controller only reflect the error to USB General Status Register.
(4) If “Extra SOF” error has occurred, ES bit (Bit 1) in USB General Status Register2 will be set.
In this case, USB Controller only reflect the error to USB General Status Register.
USB Controller can detect the other Error listed below.
Isochronous data oversize error:
If received data packet size is over MaxPacketSize of
EndPoint2, USB Controller will set EP2OS bit (Bit 7) in USB
General Status Register2.
Incorrect EndPoint Number:
If received IN/OUT TOKEN packet includes the EndPoint
Number which is not enabled by V
R
4120A RISC Processor or
which is over 7, USB Controller will set IEA bit (Bit 19) in USB
General Status Register2.
No data in EndPoint1 Tx FIFO:
If IN TOKEN packet for EndPoint2 comes when Tx FIFO for
EndPoint2 is not ready, USB Controller will not send any data