Create a compact bridge to I2C devices with FT201X and STM32L073RZ
Full speed USB to I2C bridge
Published Feb 26, 2024
Click board™
USB to I2C 2 Click
Dev. board
Nucleo-64 with STM32L073RZ MCU
Compiler
NECTO Studio
MCU
STM32L073RZ
Discover the power of full-speed USB to I2C bridge and elevate your solution to new heights
A
A
Hardware Overview
How does it work?
USB to I2C 2 Click is based on the FT201X, a USB to I2C interface device which simplifies USB implementations from FTDI. The FT201X is USB 2.0 full-speed compatible and handles the entire USB protocol by itself; no USB-specific firmware programming is required. It fully integrates 2048-byte Multi-Time-Programmable (MTP) memory for storing device descriptors, CBUS I/O user-desirable configuration, clock generation with no external crystal required, and optional clock output selection enabling a glue-less interface to external MCU or FPGA. This Click board™ communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Standard Mode operation with a clock frequency of 100kHz and Fast Mode up to 400kHz.
Since the FT201X for proper operation requires a 5V only, this Click board™ also features the PCA9306 voltage-level translator from Texas Instruments. The I2C interface bus lines are routed to the dual bidirectional voltage-level translator, allowing this Click board™ to work properly with both 3.3V and 5V MCUs. The FT201X also contains an embedded fully integrated MTP memory used to specify the functionality of the Control Bus (CBUS) pins, the current drive on each signal pin, the current limit for the USB bus, and the descriptors of the device. There are six configurable CBUS I/O pins, two routed on default AN and INT pins of the mikroBUS™ socket, marked as CB0 and CB1, alongside the two blue LED indicators labeled as CBUS0 and CBUS1 used for optional user-configurable
visual indication. The other four CBUS pins can be found on the onboard CBUS header and be used as user-configurable CBUS signals. A wide range and the way of using these pins can be found in the attached datasheet. This board also uses an active-low reset signal routed on the RST pin of the mikroBUS™ socket, which provides a reliable Power-On reset to the device's internal circuitry at Power-Up. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the 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.
Features overview
Development board
Nucleo-64 with STM32L073RZ 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-M0
MCU Memory (KB)
192
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
20480
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
Start by selecting your development board and Click board™. Begin with the Nucleo-64 with STM32L073RZ MCU as your development board.
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 to I2C 2 Click driver.
Key functions:
usbtoi2c2_write_dataThis function writes a desired number of data bytes by using I2C serial interface.usbtoi2c2_read_dataThis function reads a desired number of data bytes by using I2C serial interface.usbtoi2c2_reset_deviceThis function resets the device by toggling the RST pin state.
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 main.c
* @brief USBtoI2C2 Click example
*
* # Description
* This example demonstrates the use of USB to I2C 2 click by echoing back all
* the received messages.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and performs the click default configuration.
*
* ## Application Task
* Any data which the host PC sends to the Virtual COM Port (for example, typed into the terminal
* window in UART Terminal) will be sent over USB to the click board and then it will be read and
* echoed back by the MCU to the PC where the terminal program will display it.
*
* @note
* Make sure to download and install appropriate VCP drivers on the host PC.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "usbtoi2c2.h"
static usbtoi2c2_t usbtoi2c2;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
usbtoi2c2_cfg_t usbtoi2c2_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 " );
// Click initialization.
usbtoi2c2_cfg_setup( &usbtoi2c2_cfg );
USBTOI2C2_MAP_MIKROBUS( usbtoi2c2_cfg, MIKROBUS_1 );
if ( I2C_MASTER_ERROR == usbtoi2c2_init( &usbtoi2c2, &usbtoi2c2_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( USBTOI2C2_ERROR == usbtoi2c2_default_cfg ( &usbtoi2c2 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
uint8_t rx_data = 0;
if ( USBTOI2C2_OK == usbtoi2c2_read_data ( &usbtoi2c2, &rx_data, 1 ) )
{
if ( USBTOI2C2_OK == usbtoi2c2_write_data ( &usbtoi2c2, &rx_data, 1 ) )
{
log_printf( &logger, "%c", rx_data );
}
}
}
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
