XR16L2752
2.25V TO 5.5V DUART WITH 64-BYTE FIFO
xr
REV. 1.2.0
34
4.14
The concatenation of the contents of DLM and DLL gives the 16-bit divisor value which is used to calculate the
baud rate:
Baud Rate = (Clock Frequency / 16) / Divisor
See MCR bit-7 and the baud rate table also.
4.15
Device Identification Register (DVID) - Read Only
This register contains the device ID (0x0A for XR16C2752). Prior to reading this register, DLL and DLM should
be set to 0x00.
4.16
Device Revision Register (DREV) - Read Only
This register contains the device revision information. For example, 0x01 means revision A. Prior to reading
this register, DLL and DLM should be set to 0x00.
4.17
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).
4.18
RX/TX FIFO Level Count Register (FC) - Read-Only
This register is accessible when LCR = 0xBF. Note that this register is not identical to the FIFO Level Count
Register which is located in the general register set when FCTR bit-6 = 1 (Scratchpad Register Swap). It is
suggested to read the FIFO Level Count Register at the Scratchpad Register location when FCTR bit-6 = 1.
See
Table 12
.
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.
4.19
Feature Control Register (FCTR) - Read/Write
This register controls the XR16L2752 new functions.
FCTR[1:0]: RTS Hysteresis
User selectable RTS# hysteresis levels for hardware flow control application. After reset, these bits are set to
“0” to select the next trigger level for hardware flow control. See
Table 13 on page 19
for more details.
FCTR[2]: IrDa RX Inversion
Logic 0 = Select RX input as encoded IrDa data.
Logic 1 = Select RX input as active high encoded IrDa data.
FCTR[3]: Auto RS-485 Direction Control
Logic 0 = Standard ST16C550 mode. Transmitter generates an interrupt when transmit holding register
becomes empty and transmit shift register is shifting data out.
Logic 1 = Enable Auto RS485 Direction Control function. The direction control signal, RTS# pin, changes its
output logic state from LOW to HIGH one bit time after the last stop bit of the last character is shifted out.
Also, the Transmit interrupt generation is delayed until the transmitter shift register becomes empty. The
RTS# output pin will automatically return LOW when a data byte is loaded into the TX FIFO. However, RTS#
behavior can be inverted by setting EMSR[3] = 1.
Baud Rate Generator Registers (DLL and DLM) - Read/Write