Achieve remote reading of heat and all other types of consumption meters with VOM452T and STM32F091RC
Mastering M-Bus networks has never been easier!
Published Feb 26, 2024
Click board™
M-Bus Master Click
Dev Board
Nucleo-64 with STM32F091RC MCU
Compiler
NECTO Studio
MCU
STM32F091RC
This solution is designed to meet the demands of the new European standard for remote meter reading, making it an indispensable tool for modern energy management system
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Hardware Overview
How does it work?
M-Bus Master Click is based on the VOM452, an analog, high speed, high noise immunity, 1 MBd optocoupler, from Vishay Semiconductors. The remote reading of heat meters can take place in different ways. Besides the remote reading, the whole collection of various meters can be remotely controlled over M-Bus, making it a complete housing solution. The latter is a logical continuation/extension of the technical development of consumption meters and is realizable with the help of the M-Bus Click. In order to realize an extensive bus network with low cost for the transmission medium, a two-wire cable was used together with serial data transfer. In order to allow remote powering of the slaves, the bits on the bus are represented as follows. The transfer of bits from master to slave is accomplished by means of voltage level shifts. A logical "1" (Mark) corresponds to a nominal voltage of +36 V at the output of the bus driver (repeater)
which is a part of the master; when a logical "0" (Space) is sent, the repeater reduces the bus voltage by 12 V to a nominal +24 V at its output. Bits sent in the direction from slave to master are coded by modulating the current consumption of the slave. A logical "1" is represented by a constant (versus voltage, temperature and time) current of up to 1.5 mA, and a logical "0" (Space) by an increased current drain requirement by the slave of additional 11-20 mA. The mark state current can be used to power the interface and possibly the meter or sensor itself. As mentioned above, M-Bus standard has predefined voltage levels and principle of work. In order to achieve that, M-Bus Master click has built in complete solution for master node on the network, based on MC33072ADR2G – monolithic, single supply 3 - 44 V operational amplifier from ON Semiconductor. Besides the operational amplifier, this click board has all other needed components needed to
achieve a complete analog solution which, on its output, fulfils the M-Bus voltage and current predefined specifications. This Click board™ also has VOM452 from Vishay Semiconductors. Theese high speed optocouplers, each consists of a GaAlAs infrared emitting diode, optically coupled with an integrated photo detector and a high speed transistor. The photo detector is junction isolated from the transistor to reduce miller capacitance effects. The open collector output function allows circuit designers to adjust the load conditions when interfacing with different logic systems such as TTL, CMOS, etc. All these features improve the reliability of the whole circuit, while enabling the galvanic isolation. M-Bus Master click offers a selection between 3.3V and 5V operation, with the onboard SMD jumper, labeled as PWR SEL. This allows both 3.3V and 5V MCUs to be interfaced with this Click board™.
Features overview
Development board
Nucleo-64 with STM32F091RC 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)
256
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
Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Nucleo-64 with STM32F091RC MCU as your development board.
Track your results in real time
Application Output via Debug Mode
1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.
2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.
Software Support
Library Description
This library contains API for M-Bus Master Click driver.
Key functions:
mbusmaster_generic_write- Generic write function.mbusmaster_generic_read- Generic read function.
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
* \brief MBusMaster Click example
*
* # Description
* This example reads and processes data from M-Bus Master clicks.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver.
*
* ## Application Task
* Depending on the selected mode, it reads all the received data or sends the desired message
* every 2 seconds.
*
* ## Additional Function
* - mbusmaster_process ( ) - The general process of collecting the received data.
*
* @note
* - M-Bus master communication works at 36v.
* - This click acts only as 'master', therefore it must be connected to appropriate 'slave'.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "mbusmaster.h"
#define PROCESS_RX_BUFFER_SIZE 500
#define TEXT_TO_SEND "MikroE - M-Bus Master click board\r\n"
// #define DEMO_APP_RECEIVER
#define DEMO_APP_TRANSMITTER
// ------------------------------------------------------------------ VARIABLES
static mbusmaster_t mbusmaster;
static log_t logger;
// ------------------------------------------------------- ADDITIONAL FUNCTIONS
static void mbusmaster_process ( void )
{
int32_t rsp_size;
char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
uint8_t check_buf_cnt;
rsp_size = mbusmaster_generic_read( &mbusmaster, uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );
if ( rsp_size > 0 )
{
for ( uint8_t cnt = 0; cnt < rsp_size; cnt++ )
{
log_printf( &logger, "%c", uart_rx_buffer[ cnt ] );
if ( uart_rx_buffer[ cnt ] == '\n' )
{
log_printf( &logger, "--------------------------------\r\n" );
}
}
}
}
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
mbusmaster_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 ----" );
Delay_ms( 100 );
// Click initialization.
mbusmaster_cfg_setup( &cfg );
MBUSMASTER_MAP_MIKROBUS( cfg, MIKROBUS_1 );
mbusmaster_init( &mbusmaster, &cfg );
Delay_ms( 100 );
}
void application_task ( void )
{
#ifdef DEMO_APP_RECEIVER
mbusmaster_process( );
#endif
#ifdef DEMO_APP_TRANSMITTER
mbusmaster_generic_write( &mbusmaster, TEXT_TO_SEND, strlen( TEXT_TO_SEND ) );
log_info( &logger, "---- Data sent ----" );
Delay_ms( 2000 );
#endif
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
