at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 1048

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

49.3.16.3
49.3.17
49.3.17.1
49.3.17.2
1048
AT91SAM9263 Preliminary
USART
Remote Wakeup Event
RXBRK Flag Error in Asynchronous Mode
RTS not Expected Behavior
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.
Conditions:
When a Remote Wakeup event occurs on a downstream port, the OHCI Host controller begins
to send resume signaling to the device. The Host controller should 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, it
will remain in the suspend state.
Problem Fix/Workaround
Host stack can do a port resume after it sets the HcControl.HCFS to USBOPERATIONAL.
When timeguard is 0, RXBRK is not set when the break character is located just after the Stop
Bit. FRAME (Frame Error) is set instead.
Problem Fix/Workaround
Timeguard should be > 0.
Problem Fix/Workaround
None.
1. Setting the receiver to hardware handshaking mode drops RTS line to low level even if
2. Disabling the receiver during a PDC transfer while RXBUFF flag is '0' has no effect on
the receiver is still turned off. USART needs to be completely configured and started
before setting the receiver to hardware handshaking mode.
RTS. The only way to get the RTS line to rise to high level is to reset both PDMA buffers
by writing the value '0' in both counter registers.
6249D–ATARM–20-Dec-07