SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 839

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

• CHMODE: Channel Mode
• MSBF: Bit Order
0: Least Significant Bit is sent/received first.
1: Most Significant Bit is sent/received first.
• CPOL: SPI Clock Polarity
CPOL = 0: The inactive state value of SPCK is logic level zero.
CPOL = 1: The inactive state value of SPCK is logic level one.
CPOL is used to determine the inactive state value of the serial clock (SPCK). It is used with CPHA to produce the required
clock/data relationship between master and slave devices.
• MODE9: 9-bit Character Length
0: CHRL defines character length.
1: 9-bit character length.
• CLKO: Clock Output Select
0: The USART does not drive the SCK pin.
1: The USART drives the SCK pin if USCLKS does not select the external clock SCK.
• OVER: Oversampling Mode
0: 16x Oversampling.
1: 8x Oversampling.
• INACK: Inhibit Non Acknowledge
0: The NACK is generated.
1: The NACK is not generated.
Note: In SPI master mode, if INACK = 0 the character transmission starts as soon as a character is written into US_THR
register (assuming TXRDY was set). When INACK is 1, an additional condition must be met. The character transmission
starts when a character is written and only if RXRDY flag is cleared (Receiver Holding Register has been read).
• DSNACK: Disable Successive NACK
0: NACK is sent on the ISO line as soon as a parity error occurs in the received character (unless INACK is set).
1: Successive parity errors are counted up to the value specified in the MAX_ITERATION field. These parity errors gener-
ate a NACK on the ISO line. As soon as this value is reached, no additional NACK is sent on the ISO line. The flag
ITERATION is asserted.
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
Value
0
1
2
3
– Applicable if USART operates in SPI Mode (Slave or Master, USART_MODE = 0xE or 0xF):
REMOTE_LOOPBACK
LOCAL_LOOPBACK
AUTOMATIC
NORMAL
Name
Description
Normal Mode
Automatic Echo. Receiver input is connected to the TXD pin.
Local Loopback. Transmitter output is connected to the Receiver Input.
Remote Loopback. RXD pin is internally connected to the TXD pin.
SAM3X/A
SAM3X/A
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