Explore the captivating world of magnetism through the lens of HMC1512 and PIC18F57Q43

Beyond the spin

Magnetic rotary Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

Magnetic rotary Click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Learn how magnetic rotary sensors go beyond mere rotations, serving as indispensable tools for innovation, enabling advancements in navigation systems, medical devices, and more

Hardware Overview

How does it work?

Magnetic rotary Click is based on the HMC1512, a magnetic displacement sensor, from Honeywell. The key feature of the HMC1512 IC is the high accuracy of the magnetic field sensing. Unlike most of the magnetic sensors on the market which rely on the Hall-effect, the integrated sensors of the HMC1512 IC are produced using the Honeywell proprietary Anisotropic Magneto-Resistive (AMR) technology, which yields an absolute magnetic field position sensing with the angular error of only 0.05° in the range of ±90°. The magneto-resistive sensing elements form a saturated-mode Wheatstone bridge, positioned in the XZ plane (parallel with the surface of the IC). The HMC1512 contains two such integrated bridges, bridge A, and bridge B. These bridges are positioned at the middle of the IC casing, which is the optimal position for rotary applications. One bridge is physically rotated by 45° from the other, allowing the HMC1512 IC to cover the full range of ±90° (2x45°), maintaining its sensing accuracy. The IC outputs an analog differential voltage with respect to the angle of the magnetic field. The

voltage from the selected mikroBUS™ power rail is directly applied to the internal Wheatstone bridge of the HMC1512. By construction, in the absence of the magnetic field, its outputs will be set at half the supply voltage (with the small offset of 3mV/V typically). If there is a magnetic field positioned at 0° in respect to one of the bridges, it will cause no disbalance of the magneto-resistive elements for that bridge. However, in the other bridge, the same magnetic field will cause it to reach its peak output value, since that bridge is rotated by 45°. The outputs of the Wheatstone bridges are routed to the dual operational amplifier, which serves as the buffer for the A/D converter. As a dual operational amplifier, the MCP6022 from Microchip is used. This op-amp is biased to half the power supply voltage and has a gain of 25. Two buffered signals are then used as inputs for each channel of the A/D converter. Magnetic rotary click uses the MCP3202, a two-channel, 12-bit A/D converter (ADC) with SPI Interface, by Microchip. This ADC has a high resolution which can be used even for more demanding applications.

At 0°, the ADC will output half of its full-scale (FS) value, and it will swing towards 0 if the sign of the orientation of the magnetic field is positioned towards the negative direction, and 4095 if the orientation of the magnetic field is positioned towards the positive direction. Each bridge output is routed to a separate ADC input, so it can be independently converted. The MCP3202 uses the power supply as the reference voltage, allowing ADC conversion within the range of the input signal. Converted output values can be read via the SPI interface, routed to the mikroBUS™ SPI pins for easy interfacing with a vast number of different microcontrollers (MCUs). This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR 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

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

8196

You complete me!

Accessories

Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.

Used MCU Pins

mikroBUS™ mapper

RST

SPI Chip Select

PD4

SPI Clock

PC6

SCK

SPI Data OUT

PC5

MISO

SPI Data IN

PC4

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

SCL

SDA

Power Supply

Ground

GND

Take a closer look

Click board™ Schematic

Magnetic rotary Click Schematic schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Charger 27 Click front image hardware assembly

PIC18F47Q10 Curiosity Nano front image hardware assembly

Board mapper by product8 hardware assembly

PIC18F57Q43 Curiosity MCU Step hardware assembly

Necto No Display image step 8 hardware assembly

Debug Image Necto Step hardware assembly

Software Support

Library Description

This library contains API for Magnetic rotary Click driver.

Key functions:

magnrotary_read_adc - This function returns a 12bit result of AD conversion
magnrotary_out_volt_adc - This function returns ADC voltage value calculated to millivolts, depending on the voltage selection
magnrotary_get_field_angle - This function returns a magnetic field angle calculated to degrees,from -90 to 90 degrees.

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 MagneticRotary Click example
 * 
 * # Description
 * On every 500 miliseconds reads a magnetic field angle calculated to degrees for channel A
 * in Single-Ended Mode and logs results on uart terminal. 
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes peripherals, pins, SPI interface for communication with the device.
 * 
 * ## Application Task  
 * Reads a magnetic field angle calculated to degrees for channel A
 * in Single-Ended Mode and logs results on uart terminal.
 * Repeats operation every 500 milliseconds.
 * Note : The angle can be measured in the range from -90 to 90 degrees.
 * 
 *
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "magneticrotary.h"

// ------------------------------------------------------------------ VARIABLES

static magneticrotary_t magneticrotary;
static log_t logger;

static double magn_angle;
// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
{
    log_cfg_t log_cfg;
    magneticrotary_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.

    magneticrotary_cfg_setup( &cfg );
    MAGNETICROTARY_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    magneticrotary_init( &magneticrotary, &cfg );
    log_info(&logger, "Magnetic rotary successufully initialized!\r\n");

}

void application_task ( void )
{
    //  Task implementation.

    magn_angle = magnrotary_get_field_angle( 
                                            &magneticrotary, MAGNROTARY_CHA_POS_GND_NEG | 
                                                             MAGNROTARY_MSB_ZEROS_ORDER );
    
    log_printf( &logger, "Angle:    %.2lf \r\n ", magn_angle );
    
    Delay_ms ( 500 );
}

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