at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 764

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

44.2.13
44.2.13.1
44.2.13.2
44.2.13.3
44.2.13.4
44.2.13.5
44.2.13.6
764
AT91SAM9260
USART
TXD signal is floating in Modem and Hardware Handshaking mod.
DCD is Active High instead of Low
RXBRK flag error in Asynchronous Mode
CTS signal in Hardware Handshake
RTS not expected behavior
Two characters sent if CTS rises during emission
TXD signal should be pulled up in Modem and Hardware Handshaking mode.
TXD is multiplexed with PIO which integrates a pull up resistor. This internal pull-up must be
enabled.
The DCD signal is active at High level in the USART Modem Mode .
DCD should be active at Low level.
Add an inverter.
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.
Timeguard should be > 0.
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit of the
transmitter, a character is lost.
CTS must not go low during a time slot comprised between 2 Master Clock periods before the
rising edge of the starting bit and 16 Master Clock periods after the rising edge of the starting bit.
None.
If CTS rises to 1 during a character transmit, the Transmit Holding Register is also transmitted if
not empty.
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
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
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.
6221G–ATARM–31-Jan-08