xr20v2170 Exar Corporation, xr20v2170 Datasheet - Page 34

• Manufacturer Part Number: xr20v2170
• Description: I2c/spi Uart With 64-byte Fifo And Rs232 Transceiver
• Manufacturer: Exar Corporation

XR20V2170
I2C/SPI UART WITH 64-BYTE FIFO AND RS232 TRANSCEIVER
EFCR[2]: Transmitter Disable
UART does not send serial data out on the TX output pin, but the TX FIFO will continue to receive data from
CPU until full. Any data in the TSR will be sent out before the trasnmitter goes into disable state.
•
•
EFCR[1] = Receiver Disable
UART will stop receiving data immediately once this bit is set to a Logic 1. Any data that is being received in
the TSR will be received correctly and sent to the RX FIFO.
•
•
EFCR[0]: Reserved
This bit is reserved and should remain at a logic 0.
These registers make-up the value of the baud rate divisor. The concatenation of the contents of DLM and
DLL is a 16-bit value is then 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.
FRACTIONAL DIVISOR” ON PAGE 10.
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.
4.20
4.21
Logic 0 = Transmitter is enabled
Logic 1 = Transmitter is disabled
Logic 0 = Receiver is enabled
Logic 1 = Receiver is disabled
Baud Rate Generator Registers (DLL, DLM and DLD[3:0]) - Read/Write
Enhanced Feature Register (EFR)
DLD[5]
0
0
1
T
ABLE
14: S
Table
SEE”PROGRAMMABLE BAUD RATE GENERATOR WITH
AMPLING
DLD[4]
15). When the Xon1 and Xon2 and Xoff1 and Xoff2 modes
34
X
0
1
R
ATE
S
ELECT
Table 14
S
AMPLING
16X
8X
4X
R
below.
ATE
REV. 1.0.0