FT232RL USB Full Speed to Serial UART IC

As with many other industries, modern computer technologies have revolutionized the communications industry. A general-purpose computer system understands and can communicate in various protocols, allowing it to communicate with a wide range of peripherals. Protocol translation is a common task in the realm of computer networking. USB and serial UART are two of the most common and widely used communication methods between computers. Data from a USB port can be translated into the universal asynchronous receiver/transmitter (UART) format using an integrated circuit chip called a USB UART interface.

What is FT232RL？

FTDI Ltd’s FT232RL is a state-of-the-art USB UART interface device with an integrated circuit. Features include the newest FTDIChip-ID security dongle technology and a clock generator output through USB on this USB to serial UART interface. The integrated circuit may operate in either synchronous or asynchronous bit bang mode.

The design process for a USB to serial UART circuit is greatly facilitated by the device’s integrated EEPROM, clock circuit, and USB resistors. External microcontrollers and digital circuitry can be powered by the 6/12/24/48MHz signal generated inside. The USB port can be used to get a unique identifier for each FT232RL chip that has been permanently written to the device’s memory. Incorporating a dongle-based security mechanism that prevents unauthorized copies of consumer data requires this distinctive identity.

How does FT232RL work?

The FT232RL chip is widely used in USB to RS-232 converters. The RS-232 serial communication standard is commonly implemented in commercial embedded systems, industrial instrumentation devices, and personal computers. Although many modern consumer electronics are equipped with USB ports, many professional and industrial tools lack this. For such applications, the FT232RL is the ideal component.

Specifications Of FT232RL

The FT232R chip has the following primary technical specifications:

• Data Transfer Rate: 300 To 3 Megabaud
• Receive Buffer Size: 256 Bit
• Internal EEPROM: 1024 Bit
• CMOS Drive Output: 5/3.3/2.8/1.8V
• Integrated Supply Filter: AVCC
• Transmit Buffer Size: 128 Bit
• FTDI Drivers: VCP, D2XX
• Clock Signal: 6/12/24/48 Mhz
• Bit Bang Modes: Synchronous, Asynchronous, CBUS
• Packages: 28 Pin SSOP, QFN-32

Features of FT232RL

Integrated Clock Circuit

FTDI’s older USB UART devices necessitated an external crystal or ceramic resonator. Since the clock circuit is built into the gadget, there is no longer any need for a particular crystal or ceramic resonator. However, if necessary, the clock can be sourced from an external 12MHz crystal.

Integrated EEPROM

To use USB Vendor ID (VID), USB Product ID (PID), serial number, and product description string different from the default settings in the device, an external EEPROM was necessary for previous generations of FTDI’s USB UART devices. The FT232R chip now incorporates an external EEPROM, allowing the product description strings to be updated across all designs. There is a user-accessible portion of the onboard EEPROM for supplemental information storage. The onboard EEPROM can be rewritten while still powered by USB.

Preprogrammed EEPROM

The EEPROM within the FT232R is pre-encoded with a serial number exclusive to that unit. Typically, this would negate the need to alter the EEPROM settings of the device.

Filtering of the AVCC power supply, which powers the onboard phase-locked loop (PLL), is now built into the device, unlike in previous generations of FTDI’s USB UART devices. An additional R-C filter was needed for this pin. The filter has been integrated onto the chip, and the formerly independent AVCC pin has been connected internally to VCC.

Enhanced Asynchronous Bit Bang Mode with RD and WR Strobes

The BM chip bit bang mode developed by FTDI is compatible with the FT232R. The eight UART lines can be converted to an 8-bit general-purpose I/O port using the bit-bang mode. A built-in timer ensures that incoming data packets are sent to the interface in a timely fashion (equivalent to the baud rate Prescaler).

Since the RD# and WR# strobes are now exposed from the FT232R device, external logic can be timed via bit bang I/O bus accesses, making this mode more flexible. A separate application note will provide further detail regarding this choice.

Integrated Power-On-Reset (POR) Circuit

To do POR, the gadget has built-in POR capabilities. The FT232R can be reset by external logic through the RESET# pin for situations where it’s necessary. In many cases, however, it is acceptable not to connect the RESET# pin or to pull it high (VCCIO).

Power Management Control for High Current, USB Bus Powered Designs

The PWREN# signal can directly drive a transistor or P-Channel MOSFET when switching power to external components. To prevent accidental power cycling while the device is powered down (PWREN# is high), the EEPROM can be configured to do a soft pull-down on the UART interface lines. This mode ensures that external circuitry controlled by PWREN# reliably resets upon power restoration by bleeding any residual voltage to GND upon power removal.

Improved EMI Performance

Reduced operating current and enhanced on-chip VCC decoupling make it much simpler to design PCBs that conform to FCC, CE, and other EMI standards.

Programmable Receive Buffer Timeout

You can set a timeout to discard any data still in the receive buffer. This time is adjustable over USB from 1ms to 255ms in 1ms increments, making the device suitable for protocols that demand fast reaction times from short data packets. The default value is 16ms.

Applications of FT232RL

The FT232RL USB to serial UART interface has the following common applications:

• USB To RS-232 / RS-422 / RS-485 Converters
• USB Data Transfer In Cellular And Cordless Phones
• Interfacing The MCU And FPGA-Based Systems With USB
• USB Smart Card Readers
• Interfacing The Legacy Peripherals With USB
• USB Flash Card Readers And Writers USB
• Wireless Modems
• PC To USB Interface In Set Top Boxes
• USB-Based Security Dongles

Last but not least

One of the more popular ICs for converting USB signals to UART signals is the FT232RL. This method eliminates the need for an external programmer by allowing you to communicate with and upload code to an Arduino or other microcontroller. The FT232RL’s required pins are conveniently broken out on a board called the FTDI Basic, which SparkFun sells. The 5-volt FTDI is necessary if you use a 5-volt device. Use a 3.3-volt FTDI if your device is 3.3 volts, as you probably already guessed. All LilyPad boards run on 3.3V.

Conclusion

As a side note, you should never try to buy cheap FT232RL chips on eBay/et al.; counterfeit ones are circulating, and you won’t know that they don’t work on windows until after you’ve assembled the device.

For more details, contact us at ICRFQ. We are the best electronic components distributor in China.

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