mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 954

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

Programmers Interface
954
TOK_PID[3]
TOK_PID[2]
TOK_PID[1]
DATA0/1
KEEP/
NINC/
OWN
DTS/
Field
7
6
5
4
3
Table 39-4. Buffer Descriptor Byte Fields (continued)
The OWN bit determines whether the microprocessor or the USB-FS currently owns the buffer.
Except when KEEP=1, the SIE writes a 0 to this bit when it has completed a token. This byte of the
BD should always be the last byte the microprocessor updates when it initializes a BD.
0
1
This bit defines if a DATA0 field (DATA0/1=0) or a DATA1 (DATA0/1=1) field was transmitted or
received. It is unchanged by the USB-FS.
Typically this bit is set (that is, 1) with ISO endpoints feeding a FIFO. The microprocessor is not
informed that a token has been processed, the data is simply transferred to or from the FIFO. If
KEEP is set, normally the NINC bit is also set to prevent address increment.
0
1
The No Increment (NINC) bit disables the DMA engine address increment. This forces the DMA
engine to read or write from the same address. This is useful for endpoints when data needs to be
read from or written to a single location such as a FIFO. Typically this bit is set with the KEEP bit
for ISO endpoints that are interfacing to a FIFO.
0
1
Setting this bit enables the USB-FS to perform Data Toggle Synchronization.
0
1
Description
• If KEEP=0, bit 1 of the current token PID is written back to the BD.
• If KEEP=1, this bit is unchanged by the USB-FS.
The microprocessor has exclusive access to the BD. The USB-FS ignores all other
fields in the BD.
USB-FS has exclusive access to the BD. After the BD has been assigned to the
USB-FS, the microprocessor should not change it in any way.
Bit 3 of the current token PID is written back in to the BD by the USB-FS. Allows the
USB-FS to release the BD when a token has been processed.
This bit is unchanged by the USB-FS. If the OWN bit also is set, the BD remains
owned by the USB-FS forever.
the USB-FS writes bit 2 of the current token PID to the BD.
This bit is unchanged by the USB-FS.
Data Toggle Synchronization is disabled.
Enables the USB-FS to perform Data Toggle Synchronization.
MCF51JF128 Reference Manual, Rev. 2, 03/2011
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