Information Technology Reference
In-Depth Information
8. The host expects to receive data.
The device expects to receive data.
9. The host expects to send data.
The device expects no data-transport phase.
10. The host expects to send data.
The device expects to send data.
11. The host expects to send data.
The device expects to receive less data than the host intends to send.
12. The host expects to send data.
The device expects to receive the exact amount of data the host
intends to send.
13. The host expects to send data.
The device expects to receive more data than the host intends to send.
The following sections summarize the device's behavior in each of the 13
cases.
The Host Expects No Data Transfer
When dCBWDataTransferLength is zero, the host expects the command to
have no data-transport phase.
In the most common situation (case 1), the device agrees that there is no
data-transport phase. The device sets bCSWStatus to 00h or 01h and sets
dCSWDataResidue to zero.
If the device expects to send (case 2) or receive (case 3) data in the
data-transport phase when the host expects no data, the devices sets bCSW-
Status to 02h and may stall the bulk IN endpoint. On receiving bCSWSta-
tus = 02h, the host ignores dCSWDataResidue and performs a reset
recovery or resets the device's port.
The Host Expects to Receive Data
When dCBWDataTransferLength is greater than zero and the Direction bit
in bmCBWFlags = 1, the host expects to receive data in the data-transport
phase.
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