As we know to interface external peripherals with computers we use USB ports. But if we wish to connect a microcontroller to a computer or laptop, then we need to convert the UART signal to USB compatible signal. Here USB is a universal serial bus it is the best form of serial transmission in digital products. However, there continues to exist abundant equipment that uses older forms of serial ports. Transmission of serial bits takes a different form in the older protocol transmissions of RS-232, RS-422, and RS-485, so converters exist to bridge the gap from old equipment to new. And UART is a universal asynchronous receiver/transmitter and is an integrated circuit used to convert parallel bytes into serial bit streams.
This type of IC is commonly found on motherboards where CPUs output data in byte format. Parallel bytes take up too much real estate, so serial formats for transmitting data are the preferred form in today’s digital age. Otherwise, both the size and cost of modern electronics would be excessive. So for this mostly we use a USB to UART converter, which is an integrated circuit used to send or receive serial data from a USB port into serial data that can be received or sent by a UART interface. UART interfaces are commonly known as RS-232, RS-422, or RS-485. These types of interfaces are commonly used for communication with hardware peripherals in digital systems.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | IC | FT232RL | 1 |
| 2. | USB | – | 1 |
| 3. | Microcontroller | – | 1 |
| 4. | Capacitor | 0.1uF,10uF | 2,1 |
Circuit Diagram
Working Explanation
As shown in the circuit, the main part of the circuit is FT232RL IC. Here USB port has only four pins +5V, D-, D+, and GND. Now the FT232 ICs pin16 (usbDM) is directly connected with D- and pin15 (usbDP) is connected with D+ of the USB port. Further, the pin1 (TxD) of FT232 should be connected with the microcontroller RxD pin and pin5 of FT232 should be connected with the microcontroller TxD pin. (Microcontrollers TxD, RxD pin number varies depending on the type of microcontroller). This FT232RL IC simplifies USB to serial designs and reduces external component count by fully integrating an external EEPROM. USB termination resistors and an integrated clock circuit that requires no external crystal, in the device. It has been designed to operate efficiently with a USB host controller by using as little as possible of the total USB bandwidth available.
Applications
USB to UART converter ICs are great parts to include in any digital design for devices intended to interface with legacy equipment. The parts allow conversion within your design blocks, removing the need for extraneous cables between devices.
