HS_USB 2.0 device
RM0082
480/844
Doc ID 018672 Rev 1
Table 390.
Out data memory: buffer status quadlet bit assignments (for Non-
Isochronous OUT)
Bit
Name
Description
[31:30]
BS
Buffer status.
This 2 bit field reports the status of the out buffer, according to encoding:
– 2'b00 Host ready. = The descriptor is available to be processed by DMA.
– 2'b01 DMA busy. = The DMA is still processing the descriptor.
– 2'b10 DMA done. = Buffer data transfer completed by DMA.
– 2'b11 Host busy. = The application is processing the descriptor.
[29:28]
Rx Sts
Receive status.
This 2 bit field reports the status of the received out data (according to
encoding), reflecting whether the out data has been correctly received or
some errors occurred:
– 2'b00 = Success.
– 2'b01 = DESERR (descriptor transfer error).
– 2'b10 = Reserved.
– 2'b11 = BUFFER (data transfer error).
Note: In particular, a DESERR receive status indicates that the out buffer
status is something other than Host ready (that is, BS not equal to 2’b00)
during descriptor fetch.
[27]
L
If set, it indicates that this descriptor is the last one of the chain.
[26:16]
Reserved
(Non ISO)
Read: undefined. Write: should be zero.
[15:00]
Rx Bytes
(Non ISO)
Received number of bytes.
Its 16 bit width allows values ranging from 0 to 64 kbytes, depending on
the packet size of data received from the USB host.