XR16M770 Datasheet, PDF (38/52 Pages) Exar Corporation – 1.62V TO 3.63V HIGH PERFORMANCE UART WITH 64-BYTE FIFO

XR16M770
1.62V TO 3.63V HIGH PERFORMANCE UART WITH 64-BYTE FIFO
REV. 1.0.0
DLD[5:4]: Sampling Rate Select
These bits select the data sampling rate. By default, the data sampling rate is 16X. The maximum data rate will
double if the 8X mode is selected and will quadruple if the 4X mode is selected. See Table 14 below.
TABLE 14: SAMPLING RATE SELECT
DLD[5]
DLD[4]
SAMPLING RATE
0
0
16X
0
1
8X
1
X
4X
DLD[6]: Independent BRG enable
• Logic 0 = The Transmitter and Receiver uses the same Baud Rate Generator. (default).
• Logic 1 = The Transmitter and Receiver uses different Baud Rate Generators. Use DLD[7] for selecting
which baud rate generator to configure.
DLD[7]: BRG select
When DLD[6] = 1, this bit selects whether the values written to DLL, DLM and DLD[5:0] will be for the Transmit
Baud Rate Generator or the Receive Baud Rate Generator. When DLD[6] = 0 (same Baud Rate Generator
used for both TX and RX), this bit must be a logic 0 to properly write to the appropriate DLL, DLM and
DLD[5:0]. .
TABLE 15: 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.
4.14 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).
4.15 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 12.
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