What is the principle of making USB-RS232 converter with CP2101 (2102)?

CP2101 (CP2102) is a product of Silicon America. It is a dedicated chip that highly integrates USB to UART functions and provides a simple solution with minimal PCB space. CP2101 includes a USB2.0 full-speed controller, USB transceiver, clock, EEPROM and asynchronous serial data bus (UART) full signal demodulation control, no external USB components are required, and the package size is 5x5mm MLP-28.

Applications:

Widely used RS232 to USB.

Cell phone USB interface cable

PDA USB interface cable

USB to RS232 serial adapter.

Virtual serial port driver.

Existing serial port applications.

· WINDOWS98/2000/XP operating system

MAC OS-9

·  WINDOWS CE.

·  Linux 2.4.

CP2101 does not require an external clock oscillator, and the peripheral circuit is very simple. The manufacturer provides free drivers suitable for multiple operating systems such as Windows (including Windows CE), Linux, Mac OS-X, etc. Users do not need to carry out secondary development of the device. They only need to install the hardware and install the driver before use. The data format of the CP2101 serial bus is: 8 data bits, 1 stop bit, and the parity bit can be selected as no parity, odd parity, or even parity. It supports standard baud rates: 300, 600, 1200, 1800, 2400, 4800, 7200, 9600, 14400, 19200, 28800, 38400,

56000, 57600, 115200, 128000, 230400, 460800.921600, etc.

The figure below is a circuit diagram of a USB-RS232 converter. We explain its principle as follows:

There is a 4.7kR resistor (R1) between the 9th pin and the 6th pin VDD of CP2101, which is added to increase the anti-interference characteristics. To reduce the internal resistance of the system power supply, a filter capacitor 4.7uF (C3) is connected between the 6th pin VDD and the ground. Capacitors C1 and C2 are designed to enhance the stability of data transmission and avoid interference in signal transmission. At the same time, there is also a large metal grounding plate at the bottom of the CP2101 chip, the purpose of which is to shield the interference of other interference sources on the data signal.

Driver Installation:

In Windows98, WIndows2000 or Windows XP operating system, double-click the executable file CP2101x_VCP_Win2k_XP_S2k3.exe to enter the installation section, step by step, until the installation is completed. After the driver is installed, check the USB converter into the computer USB interface, right-click "My Computer" - "Properties" - "Hardware" - "Device Management" - "Ports (LPT and COM)", if you can see the "CP210x USB to UART Broge Controller (COMx)" information, it means that the computer has found the device and virtually implemented serial port 3 (COM3). We can also modify COM3 to the default COM port number of some tools. For example, the default port number of some programmers is COM1. Right-click "CP210x USB to UART Brige Controller (COM3)" and select COM1 in the selection box of "Properties" - "Port Settings" - "Advanced" - "COM Port". Re-check the port (COM and LPT) to see that it has been modified successfully. When using this converter in the future, the default port is COM1.