# UART-to-TTL adapter

## **Theory**

A UART-to-TTL adapter is used to interface with UART communication ports, commonly found in embedded systems, by converting TTL (3.3V or 5V) signals to USB for interaction with a computer. The UART protocol uses three key pins: **TX** (Transmit), **RX** (Receive), and **GND** (Ground). The TX pin sends data from the device, RX receives data, and GND ensures a common reference for signal integrity. Correctly matching voltage levels (3.3V or 5V) between the adapter and the target device is crucial to prevent damage during communication.

## Usage

* Open your serial terminal software and configure the following settings:
  * **Baud Rate**: Most popular values are 9600 and 115200, or as specified in the device’s documentation (picocom also has a feature to adjust the baud rate on the fly (check docs)).
    * more common baud rates: 4800, 19200, 38400, 57600, 230400, 460800, 921600
* There are more settings you have to figure out, but the most common ones are these:
  * **Data Bits**: 8
  * **Parity**: None
  * **Stop Bits**: 1
  * **Flow Control**: None

{% tabs %}
{% tab title="Linux" %}

```bash
sudo minicom -D /dev/ttyUSB0 -b 115200
sudo picocom -b 115200 -r -l /dev/ttyUSB0
```

{% endtab %}

{% tab title="Windows" %}
**Using PuTTY (Windows)**:

* Select “Serial” and enter the COM port (e.g., COM3) and baud rate (115200).
  {% endtab %}
  {% endtabs %}

UART-TTL adapter are usually pretty cheap ($10) and compact like this model:

<figure><img src="https://812024329-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS20l0nCBFmcT2JDBwjvL%2Fuploads%2Fgit-blob-81c3389862715d288f50ed9deeb6ca3a522ddc1d%2Fimage.png?alt=media" alt=""><figcaption><p>FT232-AZ USB to TTL serial adapter</p></figcaption></figure>

Hint:

If you console looks like this, you probably have the wrong baud rate set:

<figure><img src="https://812024329-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FS20l0nCBFmcT2JDBwjvL%2Fuploads%2Fgit-blob-b086d82d7f1a09ad8a634da4cb834e3a87c1b6e5%2Fimage.png?alt=media" alt=""><figcaption><p>False baud rate set</p></figcaption></figure>

## Resources

* [RS232 vs TTL: Beginner Guide to Serial Communication](https://www.seeedstudio.com/blog/2019/12/11/rs232-vs-ttl-beginner-guide-to-serial-communication/)