Fujitsu MB96300 series Hardware Manual page 814

CHAPTER 30 USB Mini-host
30.5.8 Error Status
This chapter describes the various error types that the USB Mini-host can detect.
■ Error Status
●
Stuffing error
If 6 bits are continously equal to "1", one "0" bit must be inserted somewhere in the sequence. In
other words, if 7 bits in a row are equal to "1", the HERR:STUFF bit is set signaling thus a
stuffing error. This bit must be cleared by software. If the next token is executed without clearing
the STUFF bit, it is updated at the termination of the next token.
●
Toggle error
When an IN token is received, the HERR:TGERR bit is set if the toggle data for the data packet
and the HTOKEN:TGGL bit are compared and a match is not detected. The TGERR must be
cleared by software. If the next token is executed without clearing the TGERR bit, it is updated at
the termination of the next token.
●
CRC error
When an IN token is received, a CRC calculation is performed on the received data and CRC
with the CRC polynomial G(X) = X
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by software. If the next token is executed without clearing the CRC bit, it is updated at the
termination of the next token.
●
Time-out error
The HERR:TOUT bit is set if a data packet or handshake is not received within a given time
frame or if SE0 is detected in the received data, or a stuffing error is detected. This bit must be
cleared by software. If the next token is executed without clearing the TOUT bit, it is updated at
the termination of the next token.
●
Receive error
A receive error, HERR:RERR, is flagged if EP1 (resp. EP2) is used as the reception buffer or if
the received data size is greater than the packet size limit specified in the EP1C:PKS field (resp.
EP2C). This bit must be cleared by software. If the next token is executed without clearing the
RERR bit, it is updated at the termination of the next token.
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, then a CRC error is detected and the HERR:CRC bit is set. This bit must be cleared
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