USB UART 4 click

USB UART 4 click features well-known FT232RL USB-to-UART interface module from FDTI. It provides USB to asynchronous serial data transfer interface, allowing the microcontroller based designs to communicate with the personal computer, in a very simple way.

FT232RL is a very popular USB to UART interface IC, used on many MikroElektronika devices, both for its reliability and simplicity. USB UART 4 click is used for whenever there is a need to seamlessly and effortlessly interface the UART lines to a personal computer. It can be used with the UART terminal, found in MikroElektronika compilers.

How does it work?

The entire USB protocol is handled on the module, thus no USB specific firmware programming is required. FTDI provides royalty-free Virtual Com Port (VCP) and Direct (D2XX) drivers for all the major OSes, used on personal computers. FT232RL contains integrated 1024 Bit internal EEPROM for storing USB VID, PID, serial number, product description strings and CBUS I/O configuration.

The Baud Rate Generator provides a 16x clock input to the UART Controller from the 48MHz reference clock. It consists of a 14 bit pre-scaler and 3 register bits which provide fine tuning of the baudrate - used to divide by a number plus a fraction. This determines the baud rate of the UART, which is programmable from 183 baud to 3 Mbaud. Also non-standard baud rates are supported. The baud rate is automatically calculated by the FTDI driver, so it is enough to simply forward the desired baudrate to the driver, usually done by selecting the baudrate via the OS terminal application.

After installing the OS drivers, device is ready to be used. When plugged in, it will create a virtual COM port. Then, it can be used with the USART Terminal application, included in every mikroE compiler, for the data exchange between the MCU and the host computer, via the UART pins of the click board. More information about working with the UART communication in general can be found in the following Learn article.

This device also features the configurable CBUS pins, which can be used for several different useful functions, as for example - configurable clock out for driving the microcontroller, data LED drive, USB Sleep, PWR status and so on. By default, CBUS3 and CBUS4 pins are configured as Power Enable and Sleep options and are routed to the PWR and SLP pins of the mikroBUS™. More information about configuring the CBUS pins can be found in the FT232RL datasheet.

SLP output pin will be set to a LOW logic state during the USB suspend mode It can be used to power down external circuitry or be used for similar purposes.

PWR output pin will be set to a LOW logic state, after the device has been configured by the USB, then HIGH during the USB suspend mode. This can also be used for the powering down / power saving, by turning unneded external circuitry.

This device also supports two additional signals - RTS (Request To Send) and CTS (Clear To Send), which can used in case when the hardware flow control is used.

One feature worth mentioning is this click board™ specific shape - it is made so that can be plugged in directly into the USB Type A port. It doesn’t have a conventional USB connector, but the PCB is shaped so that the USB traces can be easily connected to the USB port. Since the FT232RL supports the unique serial number feature, this makes it handy for developing data protection devices and dongles of various kinds. Of course, it can also be used in a traditional way.

USB UART4 click also features a small low noise LDO, used to regulate the input voltage, as well as shotky and transient voltage suppression diodes, to additionally improve the circuit stability and immunity to signal interferences.

Specifications

Pinout diagram

This table shows how the pinout on USB UART 4 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	PWR	Power enable / CBUS3
Sleep / CBUS4	SLP	2	RST	INT	15	RTS	Request to send
Clear to send	CTS	3	CS	RX	14	TX	Transmit
	NC	4	SCK	TX	13	RX	Receive
	NC	5	MISO	SCL	12	NC
	NC	6	MOSI	SDA	11	NC
Power supply	+3.3V	7	3.3V	5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

USB UART 4 click electrical specifications

Onboard settings and indicators

Software support

We provide an example for USB UART 4 click inside all of our compilers. You can navigate to the demo using Project Explorer placed inside the folder named same as your development system.

Examples Description

Example application acts as a simple echo and each character is sent using the available terminal in all MikroElektronika compilers. Also, any other terminal of your choice can be used to write and read the messages.

char uard_rd;

void main() 
{
UART1_Init(9600); // Initialize UART module at 9600 bps
Delay_ms(100); // Wait for UART module to stabilize

UART1_Write_Text("Start");
UART1_Write(13);
UART1_Write(10);

while (1) 
{
if (UART1_Data_Ready()) 
{
uart_rd = UART1_Read(); // read the received data,
UART1_Write(uart_rd); // and send data via UART
}
}
}

Downloads

mikroBUS™ Standard specification

USB UART 4 click schematic