XR16M890_11 Datasheet, PDF (46/63 Pages) Exar Corporation – UART WITH 128-BYTE FIFO AND INTEGRATED LEVEL SHIFTERS

XR16M890
UART WITH 128-BYTE FIFO AND INTEGRATED LEVEL SHIFTERS
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REV. 1.0.0
TABLE 16: BRG SELECT
DLD[7]
DLD[6]
BRG
0
0
Transmitter and Receiver uses same BRG.
Writing to DLL, DLM and DLD[5:0] configures the BRG for both the TX and RX.
0
1
Transmitter and Receiver uses different BRGs.
Writing to DLL, DLM and DLD[5:0] configures the BRG for TX.
1
1
Transmitter and Receiver uses different BRGs.
Writing to DLL, DLM and DLD[5:0] configures the BRG for RX.
1
0
Transmitter and Receiver uses same BRG.
Writing to DLL, DLM and DLD[5:0] has no effect on BRG used by the TX and RX.
3.16 Trigger Level Register (TRG) - Write-Only
User Programmable Transmit/Receive Trigger Level Register.
TRG[7:0]: Trigger Level Register
These bits are used to program desired trigger levels when trigger Table-D is selected. FCTR bit-7 selects
between programming the RX Trigger Level (a logic 0) and the TX Trigger Level (a logic 1).
3.17 RX/TX FIFO Level Count Register (FC) - Read-Only
This register replaces SPR (during a read) and is accessible when FCTR[6] = 1. This register is also
accessible when LCR = 0xBF. It is suggested to read the FIFO Level Count Register at the Scratchpad
Register location when FCTR bit-6 = 1. See Table 14.
FC[7:0]: RX/TX FIFO Level Count
Receive/Transmit FIFO Level Count. Number of characters in Receiver FIFO (FCTR[7] = 0) or Transmitter
FIFO (FCTR[7] = 1) can be read via this register.
3.18 Feature Control Register (FCTR) - Read/Write
FCTR[0]: SLEEP/PWRDN# Function Control
• Logic 0 = SLEEP pin (input) is enabled. This pin can be used to force the XR16M890 to enter the sleep
mode immediately after the next data byte that is being transmitted on the TX pin and being received on the
RX pin has been completed.
• Logic 1 = PWRDN# pin (output) is enabled. When the XR16M890 enters the sleep mode, this pin will be
LOW. When the XR16M890 is not in sleep mode, this pin will be HIGH.
FCTR[1]: Reserved
This bit is reserved and should be ’0’.
FCTR[2]: IrDa RX Inversion
• Logic 0 = Select RX input as encoded IrDa data (Idle state will be LOW).
• Logic 1 = Select RX input as inverted encoded IrDa data (Idle state will be HIGH).
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