K60P100M100SF2RM Datasheet, PDF (1241/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Field
2
BDT_STALL
TOK_PID[0]
TOK_PID[n]
1–0
Reserved
ADDR[31:0]
Chapter 45 Universal Serial Bus OTG Controller (USBOTG)
Table 45-4. Buffer Descriptor Byte Fields (continued)
Description
Setting this bit causes the USB-FS to issue a STALL handshake if a token is received by the SIE
that would use the BDT in this location. The BDT is not consumed by the SIE (the owns bit
remains set and the rest of the BDT is unchanged) when a BDT-STALL bit is set.
• If KEEP=0, bit 0 of the current token PID is written back to the BD.
• If KEEP=1, this bit is unchanged by the USB-FS.
0
No stall issued.
1
The BDT is not consumed by the SIE (the OWN bit remains set and the rest of the
BDT is unchanged).
Bits [5:2] can also represent the current token PID. The current token PID is written back in to the
BD by the USB-FS when a transfer completes. The values written back are the token PID values
from the USB specification:
• 0x1 for an OUT token.
• 0x9 for an IN token.
• 0xd for a SETUP token.
In host mode, this field is used to report the last returned PID or a transfer status indication. The
possible values returned are:
• 0x3 DATA0
• 0xb DATA1
• 0x2 ACK
• 0xe STALL
• 0xa NAK
• 0x0 Bus Timeout
• 0xf Data Error
Reserved, should read as zeroes.
The Address bits represent the 32 -bit buffer address in system memory. These bits are
unchanged by the USB-FS.
45.3.5 USB Transaction
When the USB-FS transmits or receives data, it computes the BDT address using the
address generation shown in "Addressing Buffer Descriptor Entries" table.
If OWN =1, the following process occurs:
1. The USB-FS reads the BDT.
2. The SIE transfers the data via the DMA to or from the buffer pointed to by the
ADDR field of the BD.
3. When the TOKEN is complete, the USB-FS updates the BDT and, if KEEP=0,
changes the OWN bit to 0.
4. The STAT register is updated and the TOK_DNE interrupt is set.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1241