
CHAPTER 14 USBU (UNIVERSAL SERIAL BUS UNIT)
User’s Manual U14579EJ2V0UM
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14.4.8 GeneralTD fields
Table 14-4 shows details about the GeneralTD fields.
Table 14-4. GeneralTD Fields (1/2)
Field Name
R/W
Function
R
Buffer Rounding
1: The final data packet will not fill the defined buffer even if no error occurs.
0: The defined data buffer must be completely filled by the final data packet from the endpoint
indicated by the TD.
DP
R
Direction/PID (Process ID)
Indicates the data flow direction and PID used by the token. If the D area of the ED was set to 00 or
11, this area is meaningful for the HC.
11: Reserved
10: In (from endpoint)
01: Out (to endpoint)
00: Setup (to endpoint)
DI
R
Delay Interrupt
Indicates the time until an interrupt request is generated for reporting that TD processing is
completed. When TD processing is completed, the HC delays the generation of the interrupt
request until the frame indicated by this area. When the value of this area is 111, no interrupt
request related to the completion of this TD processing will be generated.
T
R/W
Data Toggle
This area is used for comparing/generating the data PID value (DATA0 or DATA1). It is updated
each time a data packet is successfully transmitted or received. When the MSB of this area is 0,
the data toggle is obtained from the C bit of the ED and the LSB of this area is ignored. When the
MSB of this area is 1, the LSB of this area indicates the data toggle.
EC
R/W
Error Count
This area is incremented by each transmission error. When the value of this area is 2 and an error
occurred, the error type is recorded in the CC area and the data is moved to the Done queue
(transfer completed queue). When processing is completed without an error, this area is reset to 0.
CC
R/W
Condition Code
This area is updated after processing is executed, regardless of whether or not processing is
successful. When processing is successful, this area is set to NoError (0000). Otherwise, it is set
according to the error type.
1111: NotAccessed
1110: NotAccessed
1101: BufferUnderrun
1100: BufferOverrun
1011: Reserved
1010: Reserved
1001: DataUnderrun
1000: DataOverrun
0111: UnexpectedPID
0110: PIDCheckFailure
0101: DeviceNotResponding
0100: STALL PID
0011: DataToggleMismatch
0010: BitStuffing Violation
0001: CRC Error
0000: NoError