CP2102 chip from SiLabs is a single chip USB to UART bridge IC. It requires minimal external components. CP2102 can be used to migrate legacy serial port based devices to USB. Hobbyists can use it as a powerful tool to make all kinds of PC interfaced projects. This module help all those who are comfortable with RS232/Serial Communication protocol, to build USB devices very easily.

Working

This is an USB2.0 to TTL UART Converter module which is based on CP2102 Bridge by SiLabs. This module can be used with Laptop's which don't have standard serial port. This module creates a virtual COM port using USB on your computer which can support various standard Baud Rates for serial communication. 

You just need to install the driver using a setup file which automatically installs correct driver files for Windows XP/Vista/ 7. After driver installation, plug the module into any USB port of your PC. Finally a new COM port is made available to the PC. The feature which makes it more convenient is the TTL level data i/o. So you don't need to make a RS232 to TTL converter using chips like MAX232. The Rx and Tx pin can be connected directly to the MCUs pins (assuming 5v i/o).

Pinouts

This module has 6 pin breakout which includes 

TXD = Transmit Output - Connect to Receive Pin(RXD) of Micro controller. This pin is TX pin of CP2102 on board.

RXD = Receive Input - Connect to Transmit Pin(TXD) of Micro controller. This pin is RX pin of CP2102 on board.

GND = Should be common to microcontroller ground.

3V3 = Optional output to power external circuit upto 50mA.

5V = Optional output to power external circuit upto 500mA

DTR/RST = Optional output pin to reset external microcontrollers like Arduino.

This module can be used to upload Arduino sketches onto your Arduino loaded AVR devices over RXD, TXD & DTR/RST pins of module.

High Quality USB to TTL converter, comes with a 4-pin extension cable.

Features:

Stable and reliable chipset CP2102.

USB specification 2.0 compliant with full-speed 12Mbps.

Standard USB type A male and TTL 6pin connector.

6pins for 3.3V, RST, TXD, RXD, GND & 5V.

All handshaking and modem interface signals.

Baud rates: 300 bps to 1.5 Mbps.

Byte receive buffer; 640 byte transmit buffer.

Hardware or X-On/X-Off handshaking supported.

Event character support Line break transmission.

USB suspend states supported via SUSPEND pins.

Temperature Range: -40 to +85.

Size: 42mm X 15mm.

Weight: 4g

Uses

USB to serial RS232 adapters are often used with consumer, commercial and industrial applications and USB to serial RS485/RS422 adapters are usually mainly used only with industrial applications. Currently, USB to TTL-level UART converters are used extensively by students and hobbyist as they can be directly interfaced to microcontrollers.

Adapters for converting USB to other standard or proprietary protocols also exist; however, these are usually not referred to as a serial adapter.

The primary application scenario is to enable USB-based computers to access and communicate with serial devices featuring D-Sub (usually DB9 or DB25) connectors or screw terminals, where security of the data transmission is not generally an issue.

The CP210x USB to UART Bridge Virtual COM Port (VCP) drivers are required for device operation as a Virtual COM Port to facilitate host communication with CP210x products. These devices can also interface to a host using the direct access driver.

These drivers are static examples detailed in Application Note 197: The Serial Communications Guide for the CP210x.

The CP210x Manufacturing DLL and Runtime DLL have been updated and must be used with v 6.0 and later of the CP210x Windows VCP Driver. Application Note Software downloads affected are AN144SW.zip, AN205SW.zip and AN223SW.zip. If you are using a 5.x driver and need support you can download Legacy OS Software.

USB serial adapters can be isolated or non-isolated. The isolated version has opto-couplers and/or surge suppressors to prevent static electricity or other high-voltage surges to enter the data lines thereby preventing data loss and damage to the adapter and connected serial device. The non-isolated version has no protection against static electricity or voltage surges, which is why this version is usually recommended for only non-critical applications and at short communication ranges.

Architecture

Die of a PL2303HX USB to Serial Bridge Controller manufactured by Prolific Technology.

As a simplified example a typical standard USB to serial adapter consists of a USB processor chip which processes the USB signals. The USB processor sends the processed USB signals to a serial driver chip which applies the correct voltages and sends the processed data signals to the serial output

For the computer to be able to detect and process the data signals drivers must be installed on the computer. Some chip models have drivers installed by default, including FTDI, while drivers for other chip models must be manually installed (e.g. for Windows and MacOS, WCH CH340,[2] Silicon Labs 210x, Prolific PL2303)

When the USB to serial adapter is connected to the computer via the USB port the driver on the computer creates a virtual COM port which shows up in Device Manager on Windows, and under /dev on Linux and MacOS.

This virtual COM port can be accessed and used as if it was a built-in serial COM port. However, the characteristics of the virtual COM port are not exactly the same as a real internal COM port, mainly due to data latency; which means that if very sensitive and precise data transfer is required, the USB to serial adapter might be unreliable and not a desired solution.[5] Virtual COM drivers are usually available for Windows, Linux and Mac only.

DETAILS

Originally, there were three individual utilities for programming CP210x devices:

CP210xSetIDs.exe - responsible for setting the USB configuration options for a device: Serial string, product string, VID/PID, etc.

CP210xPortConfig.exe - responsible for setting the device's port configuration : push/pull, enabling RS-485 functionality, etc.

CP210xBaudRateAliasConfig.exe - responsible for setting custom baud rate aliasing options on CP2102/CP2109 devices.