FTDI and UART serve different roles in serial communication. FTDI (Future Technology Devices International) is best known for its USB-to-serial converter chips (e.g., FT232RL).
In contrast, a UART (Universal Asynchronous Receiver/Transmitter) is the underlying hardware interface and protocol for asynchronous serial data transfer. FTDI chips essentially act as a bridge between USB ports and UART serial lines, whereas UART is the native serial interface itself.
As an analogy, think of an FTDI adapter as a translator. A UART only “speaks” raw serial (asynchronous TX/RX signals), but an FTDI chip encapsulates that serial data into USB packets for transmission over a USB cable.
FTDI requires a USB driver on the host (which creates a virtual COM port), whereas a native UART link requires no driver; it is simply a direct voltage-level signal between devices.
FTDI USB-to-Serial Converters
FTDI USB-to-serial adapters (such as cables or breakout boards) contain a chip that converts USB signals to UART signals. For example, the Adafruit FTDI TTL-232R cable (shown above) uses an FT232RL chip, so a PC’s USB port becomes a virtual serial port.
FTDI chips support multiple serial standards (TTL, RS-232, RS-485) and handle all hardware USB protocols. Using an FTDI adapter lets the host read/write serial data over USB, as if it were a native serial port.
These adapters often allow the selection of the UART voltage. For instance, Adafruit’s TTL-232R is “5V-logic compliant,” meaning it works with either 3.3V or 5V UART devices without extra level shifting.
What is a UART?
A UART is the built-in serial transceiver inside microcontrollers or standalone chips. It takes bytes of parallel data, adds start/stop (and optional parity) bits, and shifts the bits out serially on the TX pin (and reads bits on the RX pin). Most MCU UARTs use TTL-level signals (0–5V or 0–3.3V logic). (TTL stands for Transistor–Transistor Logic.)
In contrast, the legacy RS-232 standard uses higher ± voltage swings and inverted logic. Because of these voltage differences, a standard UART typically requires an external level shifter (e.g., a MAX232 transceiver) to interface with true RS-232 ports.
Key Differences
| Feature | FTDI (USB Bridge) | UART (native) |
|---|---|---|
| Interface | USB on one side; UART (TTL/RS-232/RS-485) on the other | Direct TX/RX pins at TTL logic levels (no USB) |
| Max Speed | Very high (USB 2.0 up to ~480 Mbps) | Lower (typically a few Mbps maximum) |
| Use Case | Bridges PC USB to device serial (requires USB drivers) | On-board serial comm. for microcontrollers/peripherals (no USB) |
| Examples | USB-to-UART adapter cables, FTDI breakout modules | MCU UART pins (e.g. Arduino TX/RX), sensor or modem serial lines |
Applications and Examples
FTDI adapters are used whenever a USB-only host needs to communicate with a serial device. For example, many Arduino boards (such as older Unos) used a built-in FT232R chip (later an ATmega16U2) to enable the PC to program the MCU over USB. Standalone FTDI cables and modules are common tools for flashing firmware or reading debug output from devices with only UART pins.
Conversely, UART interfaces are ubiquitous in embedded systems and peripherals (GPS modules, Bluetooth adapters, etc.), without requiring USB. A raw UART can often be connected directly—for example, two microcontrollers can communicate by wiring TX to RX—but when a PC USB port is in the loop, an FTDI converter is needed.
Conclusion
FTDI and UART play related but distinct roles. FTDI refers to the specific hardware (and cables) that convert USB signals into serial data. UART is the built-in asynchronous serial interface and protocol inside devices. In practice, an FTDI converter sits on top of a UART interface to add USB connectivity, while a native UART port is simply the raw serial interface.
Understanding this distinction is essential when integrating USB-equipped PCs with traditional serial devices. For example, to program a microcontroller via USB, you need an FTDI cable, whereas two microcontrollers with UART ports can communicate directly.
Alex Wang is the Marketing Manager at Romtronic, with a degree in International Business and over seven years of experience in the electronic cable and wire harness industry. He leads marketing efforts across North and South America, combining deep industry knowledge with strong sales experience.
In addition to overseeing global marketing strategy, Alex is also responsible for content development and editorial coordination, ensuring that Romtronic’s messaging remains clear, consistent, and engaging. His strength in market analysis and customer-focused approach helps clients make more informed purchasing and sales decisions.
