Our USB to UART communication interface bridge solution streamlines data exchange between USB and UART devices, ensuring fast and error-free connectivity.
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Hardware Overview
How does it work?
USB UART 3 Click is based on the CP2102N, a highly integrated USB to UART interface, from Silicon Labs. This IC adds USB to UART communication for embedded applications, registering itself as the virtual COM port, once the required drivers are installed. The device itself features the entire stack needed for the communication, so no firmware is required to handle the data transfer process between the UART and the USB. It offers a range of data rates from 300bps up to 3Mbps, hardware flow control support, 512 bytes long FIFO buffer, USB suspend and wakeup, 960 bytes of non-volatile configuration memory (EEPROM), and more. The device comes with the pre-programmed factory settings, so it works as the virtual COM port device, requiring the appropriate Virtual COM port device drivers. In this scenario, it will offer a fully RS232 compliant virtual COM port, which can be used and configured as any other COM port on the computer, with the USB data available at the UART RX and TX pins. The USB port of the Click board™ is ESD protected by the USBLC6-2SC6, a very low capacitance ESD protection IC, and it is compliant with the USB 2.0 standard. When using the USBXpress™ drivers, the device can be configured by using the Xpress Configurator in the Simplicity Studio, a software application, developed by Silicon Labs. This provides a graphical user interface for simplified configuration of the various parameters of this device. By configuring the communication to use the hardware handshaking, it is possible to utilize the internal FIFO buffer for improved speed and
reliability. This will require using the RTS and CTS pins. Hardware flow control uses these pins to signal nearly full status of the internal FIFO buffer. RTS pin will report that the FIFO buffer is almost full by being pulled to a HIGH logic level. On the other side, the CTS pin detects this condition, and when pulled to a HIGH logic level, the data will not be sent anymore (up to two bytes will be sent after the CTS pin is driven to a HIGH logic state). By using the hardware flow control, no receiver overrun conditions will occur at high baud rates. Therefore, it is advised to use it for high baud rate communication - 1 Mbaud or more. Software handshaking is also supported, by using the XON and XOFF characters. RTS and CTS pins are routed to the mikroBUS™ INT and CS pins, respectively. USB suspend event will be indicated on two CP2102N pins: SUSPEND and SUSPEND#. These pins will be pulled to a LOW and HIGH level respectively when the USB port suspends the IC. The SUSPEND# line is used to light up a LED indicator labeled as SUSP, while the SUSPEND pin is routed to the AN pin of the mikroBUS™, indicating the USB suspend event to the MCU. This can be used for power saving purposes, as the external circuitry can be turned off in the case of USB suspend event. The device also features a Remote Wake function. When the USB port is in suspend mode, by pulling the WAKEUP pin to a LOW logic level, the CP2102N will begin the USB wake-up sequence. Please note that the operating system has to allow this, by setting the appropriate power management options (in Windows OS navigate to Properties > Power Management >
Allow this device to wake up the computer). The WAKEUP pin is routed to the PWM pin of the mikroBUS™. The WAKEUP pin is multiplexed with the GPIO3 pin function and it can be reconfigured if the WAKEUP function is not required. A hardware reset pin is also available. This pin is routed to the mikroBUS™ RST pin, and driving it to a LOW logic level will reinitialize the device. Note that the SUSP LED will be lit after POR or any other type of reset, during the USB Enumeration sequence. UART RX and TX pins are routed to the appropriate mikroBUS™ UART pins and are used to send (receive) UART type of communication from (to) the host MCU. The UART data is exchanged by these pins with the internal FIFO buffer. This allows the USB transceiver to send (receive) data packets to (from) the computer and exchange them with the UART section. The data traffic is indicated by two onboard LED indicators labeled as TX and RX. These LEDs are multiplexed with the GPIO0 and GPIO1 pin functions, so changing them in the configurator is not advised. Silicon Labs offer an extensive documentation, explaining operation and functionality of their software application, so it can be referenced if more information is required. The link to the virtual COM port drivers is provided below, in the downloads section. The drivers will be installed according to the configurable PID and VID values of the CP2102N device. By default, the device is set to work as the virtual COM port (VCP) USB to UART bridge. For building customized drivers, please consult the Silicon Labs documentation.
Features overview
Development board
Nucleo-64 with STM32F410RB MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU

Architecture
ARM Cortex-M4
MCU Memory (KB)
128
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
32768
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the STM32 Nucleo-64 board with our Click Shield for Nucleo-64, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic

Step by step
Project assembly
Track your results in real time
Application Output
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support
Library Description
This library contains API for USB UART 3 Click driver.
Key functions:
usbuart3_reset
- Function for resetusbuart3_get_susp
- Set device modeusbuart3_send_command
- Function for send command
Open Source
Code example
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* \file
* \brief UsbUart3 Click example
*
* # Description
* This example reads and processes data from USB UART 3 clicks.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes driver and power module.
*
* ## Application Task
* Reads data and echos it back to device and logs it to board.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "usbuart3.h"
#include "string.h"
#define PROCESS_RX_BUFFER_SIZE 500
// ------------------------------------------------------------------ VARIABLES
static usbuart3_t usbuart3;
static log_t logger;
static int32_t rsp_size;
static char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
usbuart3_cfg_t cfg;
/**
* Logger initialization.
* Default baud rate: 115200
* Default log level: LOG_LEVEL_DEBUG
* @note If USB_UART_RX and USB_UART_TX
* are defined as HAL_PIN_NC, you will
* need to define them manually for log to work.
* See @b LOG_MAP_USB_UART macro definition for detailed explanation.
*/
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
log_info( &logger, "---- Application Init ----" );
// Click initialization.
usbuart3_cfg_setup( &cfg );
USBUART3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
usbuart3_init( &usbuart3, &cfg );
usbuart3_reset( &usbuart3 );
}
void application_task ( void )
{
rsp_size = usbuart3_generic_read( &usbuart3, uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );
if ( rsp_size > 0 )
{
usbuart3_generic_write( &usbuart3, uart_rx_buffer, rsp_size );
log_printf( &logger, "%s", uart_rx_buffer );
memset( uart_rx_buffer, 0, rsp_size );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
/*!
* \file
* \brief UsbUart3 Click example
*
* # Description
* This example reads and processes data from USB UART 3 clicks.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes driver and power module.
*
* ## Application Task
* Reads data and echos it back to device and logs it to board.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "usbuart3.h"
#include "string.h"
#define PROCESS_RX_BUFFER_SIZE 500
// ------------------------------------------------------------------ VARIABLES
static usbuart3_t usbuart3;
static log_t logger;
static int32_t rsp_size;
static char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
usbuart3_cfg_t cfg;
/**
* Logger initialization.
* Default baud rate: 115200
* Default log level: LOG_LEVEL_DEBUG
* @note If USB_UART_RX and USB_UART_TX
* are defined as HAL_PIN_NC, you will
* need to define them manually for log to work.
* See @b LOG_MAP_USB_UART macro definition for detailed explanation.
*/
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
log_info( &logger, "---- Application Init ----" );
// Click initialization.
usbuart3_cfg_setup( &cfg );
USBUART3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
usbuart3_init( &usbuart3, &cfg );
usbuart3_reset( &usbuart3 );
}
void application_task ( void )
{
rsp_size = usbuart3_generic_read( &usbuart3, uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );
if ( rsp_size > 0 )
{
usbuart3_generic_write( &usbuart3, uart_rx_buffer, rsp_size );
log_printf( &logger, "%s", uart_rx_buffer );
memset( uart_rx_buffer, 0, rsp_size );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
/*!
* \file
* \brief UsbUart3 Click example
*
* # Description
* This example reads and processes data from USB UART 3 clicks.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes driver and power module.
*
* ## Application Task
* Reads data and echos it back to device and logs it to board.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "usbuart3.h"
#include "string.h"
#define PROCESS_RX_BUFFER_SIZE 500
// ------------------------------------------------------------------ VARIABLES
static usbuart3_t usbuart3;
static log_t logger;
static int32_t rsp_size;
static char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
usbuart3_cfg_t cfg;
/**
* Logger initialization.
* Default baud rate: 115200
* Default log level: LOG_LEVEL_DEBUG
* @note If USB_UART_RX and USB_UART_TX
* are defined as HAL_PIN_NC, you will
* need to define them manually for log to work.
* See @b LOG_MAP_USB_UART macro definition for detailed explanation.
*/
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
log_info( &logger, "---- Application Init ----" );
// Click initialization.
usbuart3_cfg_setup( &cfg );
USBUART3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
usbuart3_init( &usbuart3, &cfg );
usbuart3_reset( &usbuart3 );
}
void application_task ( void )
{
rsp_size = usbuart3_generic_read( &usbuart3, uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );
if ( rsp_size > 0 )
{
usbuart3_generic_write( &usbuart3, uart_rx_buffer, rsp_size );
log_printf( &logger, "%s", uart_rx_buffer );
memset( uart_rx_buffer, 0, rsp_size );
}
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END