mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 955

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

39.3.5 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:
Freescale Semiconductor, Inc.
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
3. When the TOKEN is complete, the USB-FS updates the BDT and, if KEEP=0,
4. The STAT register is updated and the TOK_DNE interrupt is set.
ADDR field of the BD.
changes the OWN bit to 0.
BDT_STALL
TOK_PID[0]
TOK_PID[n]
ADDR[31:0]
Reserved
Field
1–0
2
Table 39-4. Buffer Descriptor Byte Fields (continued)
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.
0
1
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:
In host mode, this field is used to report the last returned PID or a transfer status indication. The
possible values returned are:
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.
Description
• 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.
• 0x1 for an OUT token.
• 0x9 for an IN token.
• 0xd for a SETUP token.
• 0x3 DATA0
• 0xb DATA1
• 0x2 ACK
• 0xe STALL
• 0xa NAK
• 0x0 Bus Timeout
• 0xf Data Error
No stall issued.
The BDT is not consumed by the SIE (the OWN bit remains set and the rest of the
BDT is unchanged).
MCF51JF128 Reference Manual, Rev. 2, 03/2011
Preliminary
Chapter 39 Universal Serial Bus (USB) Controller
955