Translate 24V sensor outputs to 5V CMOS-compatible signals with MAX31910 and STM32L152RE
Your gateway to industrial signal serialization
Published Oct 08, 2024
Click board™
Serializer Click
Dev. board
Nucleo 64 with STM32L152RE MCU
Compiler
NECTO Studio
MCU
STM32L152RE
The purpose of this solution is to simplify the complexity of sensor data conversion, empowering your automation projects with efficient 5V CMOS-compatible signals
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Hardware Overview
How does it work?
Serializer Click is based on the MAX31910, an eight-channel digital input translator/serializer for high-channel density digital input modules in industrial and process automation from Maxim Integrated, now part of Analog Devices. It features integrated current limiting, low-pass filtering, and channel serialization. Input current limiting allows a significant power reduction consumed from the field voltage supply (external typical 24V) compared to traditional discrete resistor-divider implementations. The device uses patent-pending circuit techniques to reduce power beyond possible input current, further limiting alone. The MAX31910 translates, conditions, and serializes the 24V digital output of sensors and switches to 5V CMOS-compatible signals required by the MCU. It provides the front-end interface circuit of a
programmable logic controller (PLC) digital input module. Selectable on-chip low-pass filters allow flexible debouncing and filtering sensor outputs based on the application. The serializer is stackable so that any number of input channels (IN1-IN8) can be serialized and output through only one SPI-compatible port. The serializer inputs (IN1-IN8) sense field sensors' state (ON vs. OFF) by monitoring both voltage and current flowing through the sensor output. The current sinking through these input pins rises linearly with input voltage until the limit set by the current clamp is reached (set by an onboard potentiometer). Any voltage increase beyond this point does not further increase the input current. Serializer Click communicates with MCU through a standard SPI interface in a configuration with installed digital
isolators (ISO7741 and LTV-817S). Also, it uses an interrupt pin, the FLT pin of the mikroBUS™ socket, as a 'fault' indicator, which immediately notifies the host when a fault such as an overtemperature or undervoltage condition occurs. It also has a two-channel switch labeled DB, determining the current switching frequency. The current switching clock period is automatically selected according to a switch position. 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. 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.
Features overview
Development board
Nucleo-64 with STM32L152RE 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-M3
MCU Memory (KB)
512
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
81920
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 STM32L152RE 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 Serializer Click driver.
Key functions:
serializer_get_flt_pin- This function returns the fault pin logic stateserializer_read_input- This function reads the input data by using SPI serial interface, and then checks the data integrity by verifying the CRC byte.
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 Serializer Click example
*
* # Description
* This example demonstrates the use of a Serializer Click board by reading
* the state of all inputs and displaying the results on the USB UART.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and logger.
*
* ## Application Task
* Reads the state of all inputs and displays the results on the USB UART
* approximately once per second. Also, if there's any fault indication detected,
* it will be displayed accordingly.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "serializer.h"
static serializer_t serializer;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
serializer_cfg_t serializer_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.
serializer_cfg_setup( &serializer_cfg );
SERIALIZER_MAP_MIKROBUS( serializer_cfg, MIKROBUS_1 );
if ( SPI_MASTER_ERROR == serializer_init( &serializer, &serializer_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
uint8_t input_data = 0;
err_t status = serializer_read_input ( &serializer, &input_data );
if ( SERIALIZER_ERROR != status )
{
for ( uint8_t cnt = 0; cnt < 8; cnt++ )
{
log_printf( &logger, " IN%u: %s\r\n", ( uint16_t ) cnt + 1,
( char * ) ( ( input_data & ( 1 << cnt ) ) ? "High" : "Low" ) );
}
if ( status & SERIALIZER_STATUS_UNDERVOLTAGE )
{
log_info( &logger, "Undervoltage fault" );
}
if ( status & SERIALIZER_STATUS_OVERTEMPERATURE )
{
log_info( &logger, "Overtemperature fault" );
}
log_printf( &logger, "\r\n" );
Delay_ms ( 1000 );
}
}
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
