How to use a CP2102 USB to Serial Converter to log in to your Raspberry Pi?


When you buy a Raspberry Pi for the very first time and want to configure it, the most common method would be to connect a keyboard, mouse, and display to the Raspberry Pi. But this can be a very troublesome option since you might have to carry them with you when you are traveling.

Raspberry Pi connected to HDMI display, keyboard and mouse

So, the alternative option which makes it a more simple process is by using a USB to Serial adapter to establish a connection between the Raspberry Pi and your computer. In this blog, we will show you how to use a CP2102 USB to Serial Converter to log in to your Raspberry Pi quickly and easily!

However, if you have a Seeeduino XIAO with you, we recommend you follow our blog A new way to log in to your Raspberry Pi – no USB to Serial cable required to learn about logging in to your Raspberry Pi in a brand-new way!

What is Serial Communication?

Before moving on, let’s have a quick introduction to serial communication. Serial communication is a communication method used in telecommunications where data is transmitted one bit at a time in sequential order over a communication channel. It has different protocols such as CAN, ETHERNET, I2C, SPI, RS232, USB, UART, 1-Wire, and SATA.

Serial Communication Diagram

It is the simplest form of communication between a sender and a receiver and advantageous in long-haul communications.

Hardware Setup

CP2102 USB to Serial Converter Pin Map

Here we use a CP2102 USB to Serial Converter to establish a connection between your PC and your Raspberry Pi. We will now look at its pin layout.

CP2102 USB to Serial Converter to connect to Raspberry Pi
  • 3v3: 3.3V voltage output
  • TXD: Serial Output
  • RXD: Serial Input
  • GND: Ground
  • +5V: 5V voltage output

Connecting CP2102 USB to Serial Converter to Raspberry Pi

There are two ways to connect this to your Raspberry Pi

Method 1

Connect only the data communication pins (TX and RX) and the ground pin (GND) to the Raspberry Pi by powering the Raspberry Pi separately. We recommend this method because the current from the +5V pin will not be enough if you want to connect more peripherals to your Raspberry Pi.

CP2102 USB to Serial Converter connected to Raspberry Pi

Method 2

However if you only need to connect to your Raspberry Pi without it being connected to other peripherals, you can connect as follows.

CP2102 USB to Serial Converter connected to Raspberry Pi

Software Setup

Now that we have finished setting up the hardware, let’s set up the software.

Configuring the Raspberry Pi for initial boot

When you buy a Raspberry Pi, there is no operating system installed on it out of the box. So, you need to burn an operating system into a micro-SD card and then boot the Raspberry Pi from that card. However, if you have a Micro-SD card with an operating system already installed, you can directly jump to “Installing CP2102 USB drivers”.

Step 1

First, we must download a Linux-based operating system. Raspberry Pi supports various Linux distributions such as Ubuntu, but in this guide, we will use the official OS from the Raspberry Pi Foundation, which is the Raspberry Pi OS. Download it here by selecting “with desktop and recommended software” version.

Raspberry Pi OS downloads screen

Step 2

Then you need to download a software called “balenaEtcher” which is used to burn the downloaded image above and make the Raspberry Pi boot from the Micro-SD card. Click here to download the latest version of this software.

Balena Etcher Software

Step 3

Then connect a micro-SD card into the micro-SD card slot of a PC by using a micro-SD to SD card adapter. You can also use a USB Micro-SD card reader.

Step 4

After that open the “balenaEtcher” software. Then point to the location of the downloaded image, select the connected micro-SD card, and press “flash”. It will take a few minutes to complete this process.

Burning to Micro-SD through Balena Etcher

Step 5

Navigate to Raspberry Pi root folder from your PC and create a blank file called “ssh” in this directory

Step 6

Then eject the micro-SD card from PC and insert it into the Raspberry Pi.

Raspberry Pi connected to Micro-SD Card

Installing CP2102 USB drivers

Now that you can configure your Raspberry Pi for initial boot, let’s install the necessary drivers for the CP2102 to function properly.

Step 1

Navigate to this URL and download the CP2102 drivers corresponding to your operating system.

Step 2

Then open the installer and follow the installation wizard to complete the installation.

Installing Putty

You need SSH client software on your PC to communicate with your Raspberry Pi. So we are going to use “Putty” in this tutorial. Go ahead and install Putty by downloading from this link.

Log in to your Raspberry Pi

We have now set up everything necessary to log in to your Raspberry Pi using the CP2102 USB to Serial Converter.

Step 1

First, connect your Raspberry Pi to the CP2102 USB to Serial Converter as we have explained before, and open the Putty software on your PC.

Step 2

Then, set the serial port baud rate and the port (serial line) accordingly.

Putty Configuration Window

You can check for the above information by following the steps below.

  • Search for “Device Manager” on your computer
Windows Device Manager Window
  • Then head over to Ports (COM & LPT). From the drop-down menu, right-click on the USB to Serial Converter and choose “Properties”.
Choosing Serial Connection using windows device manager

Then go to the “Port Settings” tab and note the information and enter them on the Putty software.

Port settings of Serial Interface from windows device manager

Step 3

After that, you will see the startup information in the terminal window.

Raspberry Pi SSH window


We hope this blog helped you to understand about using a CP2102 USB to Serial Converter to easily log in to your Raspberry Pi without hassle!

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July 2020