Usb Controller Errors - Freescale Semiconductor MPC850 User Manual

Table 32-15. USB Command Format Field Descriptions (Continued)
Bits Name
2–3 USBCMD Contains the USB command.
01 The
10 The
All other values are reserved.
4–7 OPCODE Must be programmed to 0xF. The opcode for USB commands is 0xF.
8–11 CH_NUM Must be programmed to 0x0. The USB channel number is 0x0.
12–13 ENDPOINT Endpoint. Logical pipe number.
00 Endpoint 0
01 Endpoint 1
10 Endpoint 2
11 Endpoint 3
14 — Reserved. Should be cleared.
15 FLG Command semaphore flag. Set by the core and cleared by the CP.
0 CP is ready for a new command.
1 CP is currently processing a command—cleared when the command is done or after reset.
For the common CP commands available to the USB controller, such as
, see Table 18-7.
TX

32.10 USB Controller Errors

The USB controller reports frame reception and transmission error conditions using the
BDs and the USB event register (USBER). Transmission errors are shown in Table 32-16.
Table 32-16. USB Controller Transmission Errors
Error
Transmit If an underrun occurs, the transmitter forces a bit-stuffing violation, terminates buffer transmission,
Underrun closes the buffer, sets TxBD[UN] and the corresponding USBER[TXEn]. The endpoint resumes
transmission after the
Transmit Transmit packet not acknowledged. If a timeout occurs, the controller tries to retransmit if
Timeout USEPn[RTE] = 1. If RTE = 0 or the second attempt fails, the controller closes the buffer and sets
TxBD[TO] and USBER[TXEn]. The endpoint resumes transmission after receiving a
command.
ENDPOINT
Tx Data This error occurs if an IN token is received, but the corresponding endpoint's transmit FIFO is empty, or
Not Ready if the target endpoint is configured to NAK or STALL. The controller sets USBER[TXEn].
command disables the transmission of data on the selected
STOP TX ENDPOINT
endpoint. After issuing the command, flush the corresponding endpoint FIFO; see
Section 32.7.4, "USB Command Register (USCOM)." No further transmissions will occur
until the
RESTART TX ENDPOINT
RESTART TX ENDPOINT
corresponding endpoint on the USB. This command is expected by the USB controller
after a command or after a transmission error (underrun or timeout)
STOP TX ENDPOINT
occurs.
RESTART TX ENDPOINT
Chapter 32. Universal Serial Bus Controller
Description
command is issued.
command enables the transmission of data from the
Description
command is received.
USB Controller Errors
GRACEFUL STOP
RESTART TX