Beginner
10 min
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USB UART Click with UNI Clicker

Published Nov 02, 2023

Click board™

USB UART Click

Development board

UNI Clicker

Compiler

NECTO Studio

MCU

STM32F302VC

With our user-friendly USB to UART solution, connecting and communicating with your devices has never been simpler - just plug it in, play with the data, and enjoy seamless communication

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Hardware Overview

How does it work?

USB UART Click is based on the FT232RL, a USB to serial UART bridge from FTDI Chip. The entire USB protocol is handled on the IC; 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 also contains an integrated 1024-bit internal EEPROM for storing USB VID, PID, serial number, product description strings, and CBUS I/O configuration. After installing the OS drivers, the device is ready to be used. Plugging into the PC over the mini-USB connector will create a virtual COM port. The Baud Rate Generator provides a 16x clock input to the UART Controller from the 48MHz reference clock. 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 FTDI driver automatically calculates the baud rate, so it is enough to forward the desired baud rate to the driver, usually done by selecting the baud rate via the GUI interface of the PC terminal application. USB UART Click uses a standard 2-Wire UART interface to communicate with the host MCU, with commonly used UART RX and TX pins. In addition, you can use the UART flow control pins RTS and CTS. LEDs RX and TX are here for visual presentation of data flow. This device also features configurable CBUS pins, which can be used for several useful functions, such as configurable clock out for driving the microcontroller, data LED drive, USB Sleep, PWR status, and more. By default, CBUS3 and CBUS4 pins are configured as Power Enable (PWR) and

Sleep options (SLP). CBUS3 output pin will be set to a LOW logic state during the USB suspend mode. It can power down external circuitry or be used for similar purposes. CBUS4 output pin will be set to a LOW logic state after the USB has configured the device, then HIGH during the USB suspend mode. This can also be used for powering down/power saving by turning unneeded external circuitry. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the I/O LEVEL SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

USB UART Click hardware overview image

Features overview

Development board

UNI Clicker is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It supports a wide range of microcontrollers, such as different ARM, PIC32, dsPIC, PIC, and AVR from various vendors like Microchip, ST, NXP, and TI (regardless of their number of pins), four mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a debugger/programmer connector, and two 26-pin headers for interfacing with external electronics. Thanks to innovative manufacturing technology, it allows you to build

gadgets with unique functionalities and features quickly. Each part of the UNI Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the UNI Clicker programming method, using a third-party programmer or CODEGRIP/mikroProg connected to onboard JTAG/SWD header, the UNI Clicker board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Type-C (USB-C) connector, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or using a Li-Po/Li

Ion battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board (plus USB HOST/DEVICE), including the well-established mikroBUS™ socket, a standardized socket for the MCU card (SiBRAIN standard), and several user-configurable buttons and LED indicators. UNI Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI clicker double image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

ARM Cortex-M4

MCU Memory (KB)

256

Silicon Vendor

STMicroelectronics

Pin count

100

RAM (Bytes)

40960

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
UART CTS
PC13
RST
Sleep Mode / CBUS4
PE8
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Power Enable / CBUS3
PF9
PWM
UART RTS
PE13
INT
UART TX
PA2
TX
UART RX
PA3
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

USB UART Click Schematic schematic

Step by step

Project assembly

UNI Clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI Clicker as your development board.

UNI Clicker front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
UNI Clicker Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for USB UART Click driver.

Key functions:

  • usbuart_pwr_ctrl - This function sets the click turns click on.

  • usbuart_set_cts - This function sets CTS pin.

  • usbuart_send_command - This function is used for sending commands.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * @file main.c
 * @brief USB UART Click Example.
 *
 *# Description
 * This example reads and processes data from USB UART 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 Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "usbuart.h"
#include "string.h"

#define PROCESS_BUFFER_SIZE 100

static usbuart_t usbuart;
static log_t logger;

static char app_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    usbuart_cfg_t usbuart_cfg;  /**< Click config object. */

    /** 
     * 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 " );
    Delay_ms( 100 );

    // Click initialization.

    usbuart_cfg_setup( &usbuart_cfg );
    USBUART_MAP_MIKROBUS( usbuart_cfg, MIKROBUS_1 );
    
    err_t init_flag  = usbuart_init( &usbuart, &usbuart_cfg );
    if ( UART_ERROR == init_flag ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    app_buf_len = 0;
    
    usbuart_pwr_ctrl( &usbuart, USBUART_POWER_ON );
    usbuart_set_cts( &usbuart, USBUART_CTS_NO_ACTIVE );
    usbuart_set_mode( &usbuart, USBUART_MODE_NORMAL );
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) {
    app_buf_len = usbuart_generic_read( &usbuart, app_buf, PROCESS_BUFFER_SIZE );
    
    if ( app_buf_len > 0 ) {
        log_printf( &logger, "%s", app_buf );
        memset( app_buf, 0, PROCESS_BUFFER_SIZE );
    }
}

void main ( void ) {
    application_init( );

    for ( ; ; ) {
        application_task( );
    }
}

// ------------------------------------------------------------------------ END

Additional Support

Resources