AT91SAM9260_1 Datasheet, PDF (777/798 Pages) ATMEL Corporation – AT91 ARM Thumb Microcontrollers

AT91SAM9260
5. The Host controller raises the request for the first write transaction. By the time the
transaction is completed, a frame boundary is crossed.
6. After completing the first write transaction, the Host controller skips the second write
transaction.
Consequence: When this error occurs, the Host controller tries the same IN token again.
Problem Fix/Workaround
This problem can be avoided if the system guarantees that the status update can be completed
within the same frame.
43.3.13.2
ISO OUT Transfers
Conditions:
Consider the following sequence:
1. The Host controller sends an ISO OUT token after fetching 16 bytes of data from the
system memory.
2. When the Host controller is sending the ISO OUT data, because of system latencies,
remaining bytes of the packet are not available. This results in a buffer underrun
condition.
3. While there is an underrun condition, if the Host controller is in the process of bit-stuff-
ing, it causes the Host controller to hang.
Consequence: After the failure condition, the Host controller stops sending the SOF. This
causes the connected device to go into suspend state.
Problem Fix/Workaround
This problem can be avoided if the system can guarantee that no buffer underrun occurs during
the transfer.
43.3.13.3
Remote Wakeup Event
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.
Problem Fix/Workaround
Host stack can do a port resume after it sets the HcControl.HCFS to USBOPERATIONAL.
43.3.14 USART
43.3.14.1
TXD Signal is floating in Modem and Hardware Handshaking Mode.
TXD signal should be pulled up in Modem and Hardware Handshaking mode.
Problem Fix/Workaround
TXD is multiplexed with PIO which integrates a pull up resistor. This internal pull-up must be
enabled.
6221I–ATARM–17-Jul-09
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