NXP Semiconductors LPC1768 - Read Error Status (Command: 0 Xfb, Data: Read 1 Byte); Select Endpoint (Command: 0 X00 - 0 X1 F, Data: Read 1 Byte (Optional))

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User manual Rev. 3 — 19 December 2013 250 of 841
NXP Semiconductors
UM10360
Chapter 11: LPC176x/5x USB device controller
11.12.9 Read Error Status (Command: 0xFB, Data: read 1 byte)
This command reads the 8-bit Error register from the USB device. This register records
which error events have recently occurred in the SIE. If any of these bits are set, the
ERR_INT bit of USBDevIntSt is set. The error bits are cleared after reading this register.
11.12.10 Select Endpoint (Command: 0x00 - 0x1F, Data: read 1 byte (optional))
The Select Endpoint command initializes an internal pointer to the start of the selected
buffer in EP_RAM. Optionally, this command can be followed by a data read, which
returns some additional information on the packet(s) in the endpoint buffer(s). The
command code of the Select Endpoint command is equal to the physical endpoint
number. In the case of a single buffered endpoint the B_2_FULL bit is not valid.
Table 246. Get Error Code command bit description
Bit Symbol Value Description Reset value
3:0 EC Error Code. 0x0
0000 No Error.
0001 PID Encoding Error.
0010 Unknown PID.
0011 Unexpected Packet - any packet sequence violation from the specification.
0100 Error in Token CRC.
0101 Error in Data CRC.
0110 Time Out Error.
0111 Babble.
1000 Error in End of Packet.
1001 Sent/Received NAK.
1010 Sent Stall.
1011 Buffer Overrun Error.
1100 Sent Empty Packet (ISO Endpoints only).
1101 Bitstuff Error.
1110 Error in Sync.
1111 Wrong Toggle Bit in Data PID, ignored data.
4 EA - The Error Active bit will be reset once this register is read.
7:5 - Reserved, user software should not write ones to reserved bits. The value read
from a reserved bit is not defined.
NA
Table 247. Read Error Status command bit description
Bit Symbol Description Reset value
0 PID_ERR PID encoding error or Unknown PID or Token CRC. 0
1 UEPKT Unexpected Packet - any packet sequence violation from the specification. 0
2 DCRC Data CRC error. 0
3 TIMEOUT Time out error. 0
4 EOP End of packet error. 0
5 B_OVRN Buffer Overrun. 0
6 BTSTF Bit stuff error. 0
7 TGL_ERR Wrong toggle bit in data PID, ignored data. 0