Transform current measurements into actionable intelligence using MLX91210 and PIC18F2682
Where current measurement meets sublime precision!
Published Nov 01, 2023
Click board™
Hall Current 3 click
Dev Board
EasyPIC v8
Compiler
NECTO Studio
MCU
PIC18F2682
Enhance safety protocols and system integrity by leveraging our solution's accurate current measurements to detect irregularities and potential risks
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Hardware Overview
How does it work?
Hall Current 3 Click is based on the MLX91210, a linear Hall current sensor from Melexis. This sensor utilizes the Hall effect phenomenon to measure the current passing through the input pins of the IC. This allows the series resistance to stay very low, in magnitudes of μΩ, reducing dissipation and losses in the main current flow. The main current flow through the input rails of the IC generates a magnetic field, which causes the Hall effect on two integrated Hall plates. These two plates are connected differentially, preventing foreign magnetic interferences from influencing the measurement. A front-end section conditions and amplifies the signal, canceling out interferences. The conditioned signal is then available at the VOUT pin of the MLX91210, with a linear dependency on the input current. It is further routed to an A/D converter. The VOUT voltage is stable and has a low sensitivity drift over temperature (±1.5 % with nominal current). The VOUT pin of the
MLX91210 stays at 50% of VDD (5V) at 0A of current. This allows you to measure both polarities: positive current polarity will pull the VOUT above half of the VDD, while negative current polarity will draw the VOUT pin below the VDD voltage. The MLX91210 also features fault reporting if overvoltage, undervoltage, or calibration data CRC error occurs. It will set the VOUT pin to a high impedance mode (Hi-Z). The datasheet offers an explanation about Hi-Z timings for each type of error. The resolution of the MLX91210 IC can be determined from the full IC label: MLX91210KDF-CAS-101-SP, where CAS-101 means that it has the analog voltage resolution of 80mV/A or ±25A for the full scale (FS) measurement. The output voltage is also routed to the MCP3221, a 12 Bit SAR type ADC with the I2C interface, from Microchip. This ADC is used in several different Click board™ designs, as it yields accurate conversions, requires a low count of external components, and has a
reasonably good signal-to-noise ratio (SNR). It can achieve up to 22.3ksps, which allows good measurement resolution for most purposes. After the VOUT measurement voltage has been converted to a digital value, it can be read via the I2C bus of the MCP3221 ADC. Since the ADC IC works only with 3.3V communication voltage levels, the Click board™ is equipped with the PCA9306, a bi-directional I2C level translator. This IC accepts two voltage levels: one for the input signal and another for the output signal. The VCC SEL jumper can select the output reference signal, allowing communication with both 3.3V and 5V MCUs. The I2C bus already includes pull-up resistors, so no further configuration is needed; it can be used immediately. The input terminal has a cross-section of 2.5mm so that it can accept a high input current of more than 10A. It has two input poles: IP+ and IP-. Conductors with the current that needs to be measured can be connected to this terminal.
Features overview
Development board
EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any
circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.
Communication options such as USB-UART, USB DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
80
Silicon Vendor
Microchip
Pin count
28
RAM (Bytes)
3328
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 EasyPIC v8 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 Hall Current 3 Click driver.
Key functions:
hallcurrent3_getCurrent- This function calculates the current valuehallcurrent3_read_data- This function read two bytes of data from the specified register
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 HallCurrent3 Click example
*
* # Description
* The example starts off with the logger and click modules and then starts measuring and
* displaying current values.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes and configures the logger and click modules.
*
* ## Application Task
* Reads and displays current values every second.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "hallcurrent3.h"
// ------------------------------------------------------------------ VARIABLES
static hallcurrent3_t hallcurrent3;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( )
{
log_cfg_t log_cfg;
hallcurrent3_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.
hallcurrent3_cfg_setup( &cfg );
HALLCURRENT3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
hallcurrent3_init( &hallcurrent3, &cfg );
}
void application_task ( )
{
float current_data;
current_data = hallcurrent3_get_current( &hallcurrent3 );
log_printf( &logger, "Current : %f mA\r\n", current_data );
Delay_ms( 1000 );
}
void main ( )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
