Accurately measure bidirectional current flows with MCR1101-20-5 and STM32F091RC
Precision beyond limits!
Published Feb 26, 2024
Click board™
AMR Current Click
Dev. board
Nucleo-64 with STM32F091RC MCU
Compiler
NECTO Studio
MCU
STM32F091RC
Utilizing advanced AMR sensor tech, our solution offers precision with minimal noise, revealing current trends and optimizing system performance
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Hardware Overview
How does it work?
AMR Current Click is based on the MCR1101-20-5, an AMR-based integrated current sensor from ACEINNA. The device has superior range and accuracy (0.6% typical total error at 25°C) and 2.0% max error over temperature. It also features a Superior Frequency Response - 1.5 MHz (typically 3dB BW) and a Fast output response time (300ns typical) with a Low Primary Resistance (0.9 mΩ). The MCR1101-20-5 current sensor is factory-calibrated to achieve low offset error and provide a precise analog voltage output that is linearly proportional to the conduction current (AC or DC) with sensitivity (mV/A) compatible with A/D converters and analog control loops in power systems. The VOC pin is connected directly to VOC (Reset) pin on mikroBUS™. The voltage on this pin defines the overcurrent detection OCD threshold level. Briefly driving this pin to VCC resets and rearms OCD circuit. The AMR sensor device structure is designed to eliminate sensitivity to stray and common mode magnetic fields. Anisotropic magnetoresistance (AMR) uses a common material, Permalloy, to act as a magnetometer. Permalloy is an alloy containing roughly 80% nickel and 20% iron. The alloy's resistance depends on the angle between the magnetization and the direction of current flow. In
a magnetic field, magnetization rotates toward the direction of the magnetic field, and the rotation angle depends on the external field's magnitude. In a current sensor application, two of these resistors are connected in a Wheatstone bridge configuration to permit the measurement of the magnitude of the magnetic field produced by the current. AMR properties are well-behaved when the film's magnetic domains are aligned in the same direction. This configuration ensures high sensitivity, good repeatability, and minimal hysteresis. The film is deposited during fabrication in a strong magnetic field that sets the magnetization vector's preferred orientation, or "easy" axis, in the Permalloy resistors. AMR has better sensitivity than other methods and reasonably good temperature stability. The AMR sensor has a sensitivity that is approximately a linear function of temperature. The AMR Current has fast and accurate overcurrent fault detection circuitry. The overcurrent fault threshold (I ) is user-configurable via an external resistor divider (FLT INT) and supports a range of 120% to 200% of the full-scale primary input (IP). The sensor resistors are biased to the VCC supply voltage and produce a ratiometric differential voltage to VCC. This configuration is suited to applications where the
A-to-D or other circuitry receiving the current sensor output signals are biased by and ratiometric to the same supply voltage as the current sensor. The ratiometric configuration provides increased gain and resolution compared to fixed gain. The Click board detects the current by measuring the magnetic field generated by that current. Therefore it's important to consider the effect of externally generated magnetic fields, whether from another current flowing in the system, a magnet, or an electromagnetic component. The AMR Current click also features the MCP3221 AST, an A/D converter with a 12-bit resolution. This device provides one single-ended input with low power consumption. The AMR Current click can directly transfer the input from analog to digital because it contains the A/D converter. Also featured on the AMR Current click is the R7 resistor, which can be used if the communication goes directly to the mikroBUS™ device and is not used if you use the A/D converter (MCP3221 AST). This Click can be used for various purposes, including server, telecom & industrial PWR supplies, power aggregation, over-current protection, motor balance, remote device monitoring, and home automation control & IOT remote sensing.
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
Click board™ 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
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 AMR Current Click driver.
Key functions:
amrcurent_generic_write- This function writes data to the desired registeramrcurent_generic_read- This function reads data from the desired registeramrcurrent_read_value- This function read value
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 AMRCurent Click example
*
* # Description
* This application integrated bi-directional analog output current sensors.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializations driver init.
*
* ## Application Task
* Reading ADC data and converted current mA data from device and logs it to device.
*
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "amrcurrent.h"
// ------------------------------------------------------------------ VARIABLES
static amrcurent_t amrcurent;
static log_t logger;
uint16_t read_adc_val;
float read_curr_val;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
amrcurent_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.
amrcurent_cfg_setup( &cfg );
AMRCURENT_MAP_MIKROBUS( cfg, MIKROBUS_1 );
amrcurent_init( &amrcurent, &cfg );
}
void application_task ( void )
{
// Task implementation.
read_adc_val = amrcurrent_read_value ( &amrcurent );
log_printf( &logger, " - ADC value: %d\r\n ", read_adc_val );
Delay_ms( 100 );
read_curr_val = amrcurrent_get_current ( &amrcurent );
log_printf( &logger, " - Current value: %f\r\n ", read_curr_val );
Delay_ms( 5000 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
