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FT232RQ: A USB to UART Serial Interface

Not all interfaces work solo or independently in an Integrated Circuit (IC). Some would need additional connections in the form of a bridge to work. That aptly describes, FT232RQ a bridge connecting the Universal Serial Bus (USB) to a UART.

In this article, you will discover some of the important facts about this Integrated Circuit, cum controller.

FT232RQ as a Controller

FT232RQ is an interface classified under Integrated Circuits (ICs). Like most interfaces, it relies on the interface components to establish a connection to the various signals in a circuit board. Through these components, the interface can also transmit or transfer data or bitstream effectively.

When it comes to picking an IC-interface, the options are narrowed down to the closest functional parts. The varieties of interfaces include controllers (an example being FT232RQ), serializers, decoders and encoders. Others are splitters, capacitive touch, Universal Asynchronous Receivers and Transmitters (UARTs), Direct Digital Synthesis (DDS), signal buffers and filters.

To that end, FT232RQ fits into the category by the design as a controller. But how does a controller-based interface work?

It works by providing the “informatic connectivity” between the endpoints that comprise differing signaling methods and communication protocols.

In addition to establishing the individualized communication endpoints for these devices, the FT232RQ also supports multi-way connections.

The Bridging Perspective


When interfaces are referred to as “bridges,” it simply means that they are used as a pathway for connecting one or more interfaces.

In FT232RQ’s instance, it doubles as a bridge and a USB to UART interface. This function allows this controller to connect the Universal Serial Bus (USB) to a serial UART interface.

At the core of this connection are the following benefits:

1. Integrated Clock Generation

In addition to supporting USB to UART interface connection, FT232RQ also supports the minimization of friction during the connection.

As a way of preventing glue-less interfacing to the external Field Programmable Gate Array (FPGA) and Microcontroller (MCU), it supports the full integration of the clock generation. That way, there wouldn’t be any need for an external crystal nor an optional clock output selector.

2. Chip-Based USB Protocol

Just like the clocking peripherals are not externally added, so does the USB protocol for FT232RQ.

Since the entire USB protocol is embedded into a chip, there is no need for an external USB-specific firmware programmer to be used alongside it.

3. Buffer Distribution

Besides being an interface cum bridge for USB to UART interfacing, FT232RQ also enables higher throughputs for the data transmitted through the interface.

The high data throughput is enabled via the FIFO’s reception and transmission of buffers to attain the highest data distribution speed.

Also, it supports the use of a single-chip Universal Serial Bus (USB) to enable the asynchronous serial data transfer.

The potential to get the most of data transmission rates is also evident in the use of the 12 byte receiver buffer and the 256 byte transmit buffer. This combined byte buffers also use the buffer smoothing technology to facilitate the transfer of data at a higher speed.

At an estimate, FT232RQ’s data transfer speed or rate can move from 300 Maud up to 3 Mbaud when operating at the TTL levels.

Technical Specifications

Below are the tabulated attributes of FT232RQ’s USB to UART serial interface:

Product AttributesDescription
Operating Temperature (minimum to maximum)Between 40˚C and 85˚C
Protocol UsedUniversal Serial Bus (USB)
Current (supply)15mA
Core FunctionsUSB to UART interface and a Bridge
Package/Case32-VFQFN Exposed Pad
Type of InterfaceUART
Voltage (supply) minimum to maximum3.3 volts to 5.25 volts
USB StandardsUSB 2.0

FT232RQ’s Low Operations

FT232RQ supports the lowest levels of operations, as enshrined in the low USB bandwidth consumption, the low-power operation and the USB suspend current.

USB to UART Interfacing: What’s the Relevance?

Before USB became the in-thing, UART has been in use for a long time. The Universal Asynchronous Receiver and Transmitter (UART) interface is a communication interface, supporting the RS-232 serial data communication.

The primary use case is for the receipt and transmission (sending) of (serial) data between embedded systems.

The introduction of Universal Serial Bus (USB) became a gamechanger, as it sought to revamp the existing communication interface model and introduce a better model. The need to ensure that the UART and the USB interfaces communicate seamlessly created the need for a bridge, otherwise known as a USB to UART interface.

The interface, also called a controller or converter, aided the use of an Integrated Circuit (IC) to send and receive serial data from a USB port. The data would be further converter into a serial data, movable through the UART interface.

To maximize this conversion, the interface typically uses a combination of Rx and Tx outputs. These outputs or signals allow the interface to port to the computer, from where serial data would be sent to the port for an onward module-based conversion into the UART signals.

Now that the concept has been defined, let us now look at some of the benefits of using FT232RQ or any other USB to UART interface for serial communication data transmission:

4. USB Serial Bridges are Affordable

If you are looking for an affordable way to convert serial data from a USB to a UART port, it has to be through the USB serial bridges or ICs.

These bridges, among many other things, are cost-effective and due to the smaller real estate, can be easily replaced, rather than worked on.

5. Chip-Centric Management

FT232RQ’s core operation is based on the single chip and that also includes the entire USB protocol. With this level of management, it is clear why there is little or no need for an external, USB-centric programming firmware.

6. Small Real Estate

FT232RQ’s design allows for the best customizations, thanks to the smaller real estate. Due to the less demands for Microcontroller (MCU) resources, FT232RQ can fit into any circuit board, while packing most of the functions on a single chip.

Final Words

FT232RQ features one of the highest data transfer rates estimated at 12 Megabytes per second (Mbps). At that rate and with the bulk USB transfer modes, it sure packs a punch to deliver the most flexible USB to UART interfacing.