xr16m654 Exar Corporation, xr16m654 Datasheet - Page 38

• Manufacturer Part Number: xr16m654
• Description: 1.62v To 3.63v Quad Uart With 64-byte Fifo
• Manufacturer: Exar Corporation

XR16M654/654D
1.62V TO 3.63V QUAD UART WITH 64-BYTE FIFO
These registers make-up the value of the baud rate divisor. The concatenation of the contents of DLM and DLL
gives the 16-bit divisor value. Then the value is added to DLD[3:0]/16 to achieve the fractional baud rate
divisor. DLD must be enabled via EFR bit-4 before it can be accessed. See
2.8, Programmable Baud Rate Generator with Fractional Divisor” on page 15.
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
DLD[7:6]: Reserved
Enhanced features are enabled or disabled using this register. Bit 0-3 provide single or dual consecutive
character software flow control selection (see
are selected, the double 8-bit words are concatenated into two sequential characters. Caution: note that
whenever changing the TX or RX flow control bits, always reset all bits back to logic 0 (disable) before
programming a new setting.
EFR[3:0]: Software Flow Control Select
Single character and dual sequential characters software flow control is supported. Combinations of software
flow control can be selected by programming these bits.
4.11
4.12
Baud Rate Generator Registers (DLL and DLM) - Read/Write
Enhanced Feature Register (EFR) - Read/Write
DLD[5]
0
0
1
T
ABLE
15: S
Table
AMPLING
DLD[4]
16). When the Xon1 and Xon2 and Xoff1 and Xoff2 modes
38
X
0
1
R
ATE
S
ELECT
Table 15
Table 15
S
below and
AMPLING
16X
8X
4X
R
below.
ATE
See ”Section
REV. 1.0.0