at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 763

• Manufacturer Part Number: at91sam9260-cj
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

44.2.12.2
44.2.12.3
6221G–ATARM–31-Jan-08
ISO OUT transfers
Remote Wakeup event
Consequence: When this error occurs, the Host controller tries the same IN token again.
This problem can be avoided if the system guarantees that the status update can be completed
within the same frame.
Conditions:
Consider the following sequence:
Consequence: After the failure condition, the Host controller stops sending the SOF. This
causes the connected device to go into suspend state.
This problem can be avoided if the system can guarantee that no buffer underrun occurs during
the transfer.
Conditions:
When a Remote Wakeup event occurs on a downstream port, the OHCI Host controller begins
sending resume signaling to the device. The Host controller is supposed to send this resume
signaling for 20 ms. However, if the driver sets the HcControl.HCFS into USBOPERATIONAL
state during the resume event, then the Host controller terminates sending the resume signal
with an EOP to the device.
Consequence: If the Device does not recognize the resume (<20 ms) event, then the Device
remains in suspend state.
Host stack can do a port resume after it sets the HcControl.HCFS to USBOPERATIONAL.
1. The Host controller issues an IN token.
2. The Device provides the IN data in a short packet.
3. The Host controller writes the received data to the system memory.
4. The Host controller is now supposed to carry out two Write transactions (TD status
5. The Host controller raises the request for the first write transaction. By the time the
6. After completing the first write transaction, the Host controller skips the second write
1. The Host controller sends an ISO OUT token after fetching 16 bytes of data from the
2. When the Host controller is sending the ISO OUT data, because of system latencies,
3. While there is an underrun condition, if the Host controller is in the process of bit-stuff-
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
write and TD retirement write) to the system memory in order to complete the status
update.
transaction is completed, a frame boundary is crossed.
transaction.
system memory.
remaining bytes of the packet are not available. This results in a buffer underrun
condition.
ing, it causes the Host controller to hang.
AT91SAM9260
763