Explore the endless potential of magnet rotation with MA700 and ATmega328P

Angles in action: Innovate with magnet rotation sensing

Published Feb 14, 2024

Click board™

Angle 2 Click

Dev. board

Arduino UNO Rev3

Compiler

NECTO Studio

MCU

ATmega328P

Discover the art of magnet tilting with our innovative solution, enabling you to capture the subtleties of magnet rotation and redefine your creative possibilities.

Hardware Overview

How does it work?

Angle 2 Click is based on the MA700, an angular sensor for position control with side-shaft positioning capability, produced by Monolithic Power Systems (MPS). This IC has a set of features, critical for high-speed angular position sensing applications: it utilizes the Spinaxis frontend that allows very fast data output rates up to 500kHz, and a very low-latency data output, down to 3 µs, even when using the data filtering and conditioning options. This makes it suitable for measuring the angle of the motor shaft in various high-speed applications, such as BLDC motor applications. It can be used at speeds up to 100,000 RPM, still retaining its accuracy. The magnetic field is only sensed along the horizontal (XZ) plane by utilizing an array of aligned Hall sensors. This allows sampling of the absolute angular position of a diametrically magnetized cylinder, typically attached at the end of the rotor shaft. Unlike some other methods, the Spinaxis does not require heavy mathematical calculations, as it is based on the phase detection, directly digitizing the magnetic field direction. This is the key to an extremely low output latency of 3µs. This also allows very accurate angular position reading, as the actual physical angle coincidences with the 11-bit data available at the output, due to practically no conversion delay. The Spinaxis

frontend also allows off-axis placement of the permanent magnet, as the MA700 features built-in linearization for the side-shaft mounting in a form of an offset register. This relaxes the mechanical demands of the user application. The incremental quadrature encoder function uses three output pins: A, B, and Z. The A signal pulses 256 times during a full revolution. The B signal is shifted by a quarter of the pulse period, depending on the direction of the rotation. The application can use this fact to determine the direction of the rotation. The Z signal pulses once per 360°. The pulses on A and B outputs are affected by jitter, which can cause the output to be inconsistent if used at speeds over 30,000 RPM. For high-speed applications, using the SPI interface is recommended. The A, B, and Z pins of the MA700 IC are routed to a standard, 2.54 mm (0.1 inches) pitch 1x3 header, mounted on the Angle 2 click, so it can be easily accessed by an external application. The MA700 also features the one-time programmable (OTP) memory, which allows the working parameters of the IC to be stored as the default values. This allows a lot of flexibility for a project design since the factory pre-flashed default values might not always fit the requirements of the specific application. A typical example might be the zero position configuration:

if the sensor must be fixed to a certain angle which has to be the start position for the angle counting (the zero angle), the user application would have to internally re-calculate values to compensate, introducing more latency. The ability to define own default settings is certainly a useful option. However, flashing the OTP memory is a sensitive process, as there is very little room for an error (being one-time programmable). The datasheet of the MA700 offers a detailed guide for flashing the OTP, while Angle 2 click offers an external power supply (PSU) connector, implemented as the standard 2.54mm 1x2 header. The OTP flashing requires a separate PSU of 4V to be used. The SPI communication consists of the read/write (R/W) command, an address of the register, and the data. The R/W command and the address are two 4-bit values, while the data is a single 8-bit value. The MA700 datasheet contains the detailed information on all the commands, however, Angle 2 click comes with the library that contains very simplified angle reading functions, as well as the functions used for an easy configuring of the Angle 2 click. The MA700 SPI pins are routed to the respective pins of the mikroBUS™, allowing easy and reliable interfacing with the host MCU.

Features overview

Development board

Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an

ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the

first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.

Microcontroller Overview

MCU Card / MCU

Architecture

AVR

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

2048

You complete me!

Accessories

Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P 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 Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Used MCU Pins

mikroBUS™ mapper

RST

SPI Chip Select

PB2

SPI Clock

PB5

SCK

SPI Data OUT

PB4

MISO

SPI Data IN

PB3

MOSI

Power Supply

3.3V

Ground

GND

PWM

INT

SCL

SDA

Ground

GND

Take a closer look

Click board™ Schematic

Step by step

Project assembly

Click Shield for Arduino UNO front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.

Arduino UNO Rev3 front image hardware assembly

Barometer 13 Click front image hardware assembly

Arduino UNO Rev3 MB 1 - upright/background hardware assembly

Necto No Display image step 8 hardware assembly

Debug Image Necto Step hardware assembly

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 Angle 2 Click driver.

Key functions:

angle2_get_angle - This function reads angle data from the click module
angle2_get_angle_with_time_index - This function reads angle and time index data from the click module
angle2_set_zero_scale - This function sets the zero scale 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 Angle2 Click example
 * 
 * # Description
 * This example showcases how to configure and use the Angle 2 click. This click senses
 * the magnetic field along the horizontal plane using an array of Hal effect sensors.
 * The module uses advanced Spinaxis technology based on a direct angle sampling app-
 * roach in order to provide reliable data quickly.                                         
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * This function initializes and configures the click and logger modules. Additional con-
 * figuring is done in the default_cfg(...) function.
 * 
 * ## Application Task  
 * This function reads angle data from the click module and displays that data using the
 * UART console every 200 miliseconds.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "angle2.h"

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

static angle2_t angle2;
static log_t logger;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( )
{
    log_cfg_t log_cfg;
    angle2_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.

    angle2_cfg_setup( &cfg );
    ANGLE2_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    angle2_init( &angle2, &cfg );

    Delay_ms( 300 );
    angle2_default_cfg( &angle2 );
    Delay_ms( 200 );

    log_printf( &logger, " * Angle 2 initialized * \r\n" );
}

void application_task ( )
{
    double angle;

    angle = angle2_get_angle( &angle2 );

    log_printf( &logger, " Angle: %.2f deg\r\n", angle );

    Delay_ms( 200 );
}

void main ( )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}

// ------------------------------------------------------------------------ END