XR21B1420 Datasheet, PDF (22/60 Pages) Exar Corporation – Enhanced 1-Ch Full-Speed USB UART

XR21B1420
XON_CHAR (0x007) - Read/Write
The XON_CHAR stores the 5 through 8 bit XON character that is used for Automatic Software Flow control. In 9 bit mode,
only bits 7 through 0 are used, i.e. bit 8 is always a ’0.’ Alternately, this register holds the unicast address for multi-drop appli-
cations with address matching mode.
Bit
15:8
7:0
Default
Description
0
Reserved
These bits are reserved and should be written as ‘0’.
0x11
XON Character
In Automatic Software Flow control mode, the UART will suspend data transmission when the XON character
has been received. For behavior in the address match mode, see “Multidrop mode with address matching” on
page 14.
XOFF_CHAR (0x008) - Read/Write
The XOFF_CHAR stores the 5 through 8 bit XOFF character that is used for Automatic Software Flow control. In 9 bit mode,
only bits 7 through 0 are used, i.e. bit 8 is always a ’0.’ Alternately, this register holds the multicast address for multi-drop
applications with address matching mode.
Bit
15:8
7:0
Default
Description
0
0x13
Reserved
These bits are reserved and should be written as ‘0’.
XOFF Character
In Automatic Software Flow control mode, the UART will suspend data transmission when the XOFF character
has been received. For behavior in the address match mode, see “Multidrop mode with address matching” on
page 14.
ERROR_STATUS (0x009) - Read-Clear
This register reports any historical framing, parity and overrun errors as well as both current and historical break status,
since the last time this register was read. As such, it does not indicate which character(s) the error(s) were associated with.
For diagnostic purposes, WIDE_MODE may be enabled such that errors are directly associated with the current byte.
Bit
15:8
7
6
Default
Description
0
Reserved
These bits are reserved and should be written as ‘0’.
0
Break Status (Read-Only)
0: Break condition is not present.
1: Break condition is currently being detected.
0
Overrun Error
0: No overrun error.
1: An overrun error has been detected (clears after read). An overrun error occurs when the RX FIFO is full and
another byte of data is received.
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