CP2102N Datasheet, PDF (20/44 Pages) Silicon Laboratories – USBXpress Family

CP2102N Data Sheet
Functional Description
4.3.11 Modem Control (DSR, DTR, DCD, RI)
The modem control pins are enabled when requested on the host. If the Virtual COM Port drivers are used, the modem control pins are
enabled during COM port configuration on the PC. If the USBXpress drivers are used, the CP2102N is configured through the USBX-
press API. The behavior of the modem control pins may vary between operating systems.
Table 4.3. Modem Control Signals
Modem Control Signal
DSR
DTR
DCD
RI
Description
Input to the CP2102N. Data Set Ready control input (active low).
Output from the CP2102N. Data Terminal Ready control output (active low).
Note that this pin may toggle when opening a COM port on some operating systems.
Input to the CP2102N. Data Carrier Detect control input (active low).
Input to the CP2102N. Ring Indicator control input (active low).
4.3.12 RS485 (RS485)
The RS485 pin is an optional control pin that can be connected to the DE and RE inputs of the transceiver. When configured for RS485
mode, the pin is asserted during UART data transmission. The RS485 pin is active-high by default and is also configurable for active-
low mode using Xpress Configurator.
The RS485 pin setup and hold times are programmable using Xpress Configurator to enable maximum flexibility.
CP2102N
TX
RX
RS485
RS485
Transceiver
R
D
RE
DE
Figure 4.4. Using the CP2102N with a RS485 Transceiver
TX
Start D0 D1 D2 D3
...
Dn Stop
RS485
RS485
Setup
(tRS485S)
RS485
Hold
(tRS485H)
Figure 4.5. RS485 Output Timing Diagram for a Single-Byte Transfer
4.4 Drivers
There are two sets of device drivers available for the CP2102N devices: the Virtual COM Port (VCP) drivers and the USBXpress Direct
Access drivers. Only one set of drivers is necessary to interface with the device.
The latest drivers are available at www.silabs.com/interface-software.
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