Beginner
10 min
0

Provide precise information about the object's speed or direction of movement using H3LIS331DL and PIC18F2685

Accelerometers: The unsung heroes of the tech world

Accel 3 Click with Curiosity HPC

Published Jan 23, 2024

Click board™

Accel 3 Click

Development board

Curiosity HPC

Compiler

NECTO Studio

MCU

PIC18F2685

Accelerometers are fundamental sensors utilized across industries to measure and record changes in velocity or direction, enabling precise motion analysis and control

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Hardware Overview

How does it work?

Accel 3 Click is based on the H3LIS331DL, a low-power, high-g 3-axis digital accelerometer from STMicroelectronics. The proprietary process technology allows the processing of suspended silicon structures, which are attached to the substrate in a few points called anchors, free to move in the direction of the sensed acceleration. When acceleration is applied to the sensor, the proof mass displaces from its nominal position, causing an imbalance in the capacitive half bridge. This imbalance is measured using charge integration in response to a voltage pulse applied to the capacitor. The sensor interface is factory-calibrated for sensitivity and zero-g level. The trim values are stored inside the device in non-volatile memory. Any time the device is turned on,

the trim parameters are downloaded into the registers to be used during active operation, allowing the device to be used without further calibration. The acceleration data of Accel 3 Click is accessed through an I2C or SPI interface, with a 400KHz fast mode frequency for I2C and a 10MHz clock frequency for SPI communication. The selection is made by positioning four SMD jumpers labeled SPI I2C in an appropriate position, with the I2C set by default. Note that all the jumpers' positions must be on the same side, or the Click board™ may become unresponsive. While the I2C interface is selected, the H3LIS331DL allows choosing the least significant bit (LSB) of its I2C slave address using the SMD jumper labeled I2C ADDR (0 set by default). The H3LIS331DL

also possesses two inertial interrupts, both accessible over the INT2 INT1 jumper and INT pin of the mikroBUS™ socket. The user can completely program the functions, threshold, and timing of the two interrupt signals through the selected interface. They signal the host MCU that a motion event has been sensed. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Accel 3 Click top side image
Accel 3 Click bottom side image

Features overview

Development board

Curiosity HPC, standing for Curiosity High Pin Count (HPC) development board, supports 28- and 40-pin 8-bit PIC MCUs specially designed by Microchip for the needs of rapid development of embedded applications. This board has two unique PDIP sockets, surrounded by dual-row expansion headers, allowing connectivity to all pins on the populated PIC MCUs. It also contains a powerful onboard PICkit™ (PKOB), eliminating the need for an external programming/debugging tool, two mikroBUS™ sockets for Click board™ connectivity, a USB connector, a set of indicator LEDs, push button switches and a variable potentiometer. All

these features allow you to combine the strength of Microchip and Mikroe and create custom electronic solutions more efficiently than ever. Each part of the Curiosity HPC development board contains the components necessary for the most efficient operation of the same board. An integrated onboard PICkit™ (PKOB) allows low-voltage programming and in-circuit debugging for all supported devices. When used with the MPLAB® X Integrated Development Environment (IDE, version 3.0 or higher) or MPLAB® Xpress IDE, in-circuit debugging allows users to run, modify, and troubleshoot their custom software and hardware

quickly without the need for additional debugging tools. Besides, it includes a clean and regulated power supply block for the development board via the USB Micro-B connector, alongside all communication methods that mikroBUS™ itself supports. Curiosity HPC development board allows you to create a new application in just a few steps. Natively supported by Microchip software tools, it covers many aspects of prototyping thanks to many number of different Click boards™ (over a thousand boards), the number of which is growing daily.

Curiosity HPC double image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

96

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

3328

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
RA3
CS
SPI Clock
RB1
SCK
SPI Data OUT
RB2
MISO
SPI Data IN
RB3
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Interrupt
RB5
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RC3
SCL
I2C Data
RC4
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

Accel 3 Click Schematic schematic

Step by step

Project assembly

Curiosity HPC front no-mcu image hardware assembly

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

Curiosity HPC front no-mcu image hardware assembly
IR Sense 4 Click front image hardware assembly
MCU DIP 28 hardware assembly
Prog-cut hardware assembly
Curiosity HPC 28pin-DIP - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Necto DIP image step 7 hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for Accel 3 Click driver.

Key functions:

  • accel3_default_cfg - This function select communication mode and executes start initialization

  • accel3_read_data - This function reads Accel data ( X, Y and Z axis ) from the desired Accel registers of the H3LIS331DL module

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 Accel3 Click example
 * 
 * # Description
 * Accel 3 Click represent 3-axis linear accelerometer.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Application Init performs Logger and Click initialization.
 * 
 * ## Application Task  
 * This is an example which demonstrates the usage of Accel 3 Click board.
 * Measured coordinates (X,Y,Z) are being sent to the UART where you can 
 * track their changes. All data logs on USB UART for every 1 sec.
 * 
 * \author Mihajlo Djordjevic
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "accel3.h"

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

static accel3_t accel3;
static log_t logger;

accel3_data_t accel3_data;

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    accel3_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.

    accel3_cfg_setup( &cfg );
    ACCEL3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    accel3_init( &accel3, &cfg );
    
    log_printf( &logger, "--------------------------\r\n\n" );
    log_printf( &logger, " -----  Accel 3 Click  -----\r\n" );
    log_printf( &logger, "--------------------------\r\n\n" );
    Delay_ms ( 1000 );
    
    accel3_default_cfg ( &accel3, &cfg );
    Delay_ms ( 100 );
    
    log_printf( &logger, " -- Initialization  done. --\r\n" );
    log_printf( &logger, "--------------------------\r\n\n" );
    Delay_ms ( 1000 );
}

void application_task ( void )
{
    accel3_read_data( &accel3, &accel3_data );
    Delay_ms ( 100 );
    
    log_printf( &logger, "        Accelerometer       \r\n" );
    log_printf( &logger, "----------------------------\r\n" );
    log_printf( &logger, "        X = %d \r\n", accel3_data.x );
    log_printf( &logger, "        Y = %d \r\n", accel3_data.y );
    log_printf( &logger, "        Z = %d \r\n", accel3_data.z );
    log_printf( &logger, "----------------------------\r\n" );
    
    Delay_ms ( 1000 );
}

void main ( void )
{
    application_init( );

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

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

Additional Support

Resources