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XR21B1420 Datasheet, PDF (46/60 Pages) Exar Corporation – Enhanced 1-Ch Full-Speed USB UART
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Bit
2
1
0
Default
Description
0
TX_CLOSE
0: Do not automatically flush the TX FIFO
1: Automatically flush the TX FIFO when the COM port is closed
0
TX_OPEN
0: Do not automatically flush the TX FIFO
1: Automatically flush the TX FIFO when the COM port is opened
0
Reserved
This bit is reserved and should be written as ’0.’
XR21B1420
LOCK_BYTE_0 (0x01B) - Read/Write OTP
Each bit field in the LOCK_BYTE_0 register must be set by the user to indicate the corresponding field has been pro-
grammed. Any field that has been programmed can not be programmed again.
CAUTION: Do not set the PROG bit for any field that has not had the entire data field entered, otherwise, the empty field or
any portion thereof will be programmed (all ’0’s) into the OTP.
For definitions of the individual fields, refer to the corresponding register definition in “XR21B1420 Register Map” on page
21.
Bit
7
6
5
4
3
2
1
0
Default
Description
0
LANG_ID
0: Corresponding field has not been programmed. Values will not be read from OTP.
1: Corresponding field has been programmed. Values will be read from OTP.
0
PIN_CFG_UART3
0: Corresponding field has not been programmed. Values will not be read from OTP.
1: Corresponding field has been programmed. Values will be read from OTP.
0
PIN_CFG_UART2
0: Corresponding field has not been programmed. Values will not be read from OTP.
1: Corresponding field has been programmed. Values will be read from OTP.
0
PIN_CFG_UART1
0: Corresponding field has not been programmed. Values will not be read from OTP.
1: Corresponding field has been programmed. Values will be read from OTP.
0
PIN_CFG_UART0
0: Corresponding field has not been programmed. Values will not be read from OTP.
1: Corresponding field has been programmed. Values will be read from OTP.
0
SERIAL_STRING
0: Corresponding field has not been programmed. Values will not be read from OTP.
1: Corresponding field has been programmed. Values will be read from OTP.
0
PROD_STRING_2
0: Do not automatically flush the TX FIFO
1: Automatically flush the TX FIFO when the COM port is opened
0
PROD_STRING_1
This bit is reserved and should be written as ’0.’
© 2014 Exar Corporation
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exar.com/XR21B1420
Rev 1A
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