Usb Cp Commands - Freescale Semiconductor MPC850 User Manual

USB CP Commands

Table 32-14. TxBD Status and Control Field Descriptions (Continued)
Bits Name
1
14 UN Underrun. Indicates that the USB encountered a transmitter underrun condition while sending the
buffer.
15 — Reserved, should be cleared.
1
Written by the USB controller after it finishes sending the associated data buffer.
Data length (the second half word of a TxBD) is the number of octets the CP should send
from this BD's data buffer. It is never modified by the CP.
Tx buffer pointer (the third and fourth half words of a TxBD) always points to the first
location of the buffer in internal or external memory. The pointer may be even or odd.
32.9 USB CP Commands
The CP command register (CPCR) can be programmed with special USB commands to
transmit data. This is accomplished by adding a USBCMD field and an ENDPOINT field
to reserved areas in the basic CPCR format; see Section 18.5.3, "CP Command Register
(CPCR)." Figure 32-16 shows the USB command format of the CPCR.
Bit 0 1
Field RST —
Reset
R/W
Addr
Figure 32-16. USB Command Format of the CPCR
Table 32-15 describes fields in the USB command format.
Table 32-15. USB Command Format Field Descriptions
Bits Name
0 RST CP reset command. Set by the core and cleared by the CP. Executing this command clears
RST and FLG within two general system clocks. The CPM reset routine takes approximately
60 clocks, but CPM initialization can start immediately after this command is issued. Use RST
to reset the registers and parameters for all the channels (SCCs, USB, SMCs, SPI, and I
as well as the CPM and RISC timer table. RST does not, however, affect the serial interface or
parallel I/O registers.
0 No reset issued.
1 Reset issued.
1 — Reserved. Should be cleared.
2 3 4 5
USBCMD OPCODE
MPC850 Family User's Manual
Description
6 7 8 9
CH_NUM
0000_0000_0000_0000
R/W
0x9C0
Description
10 11 12 13
ENDPOINT
14 15
— FLG
2
C)