10 min

Detect the presence or lack of motion with ADXL345 and PIC18F85K22

Measure acceleration in three different directions

Accel Click with UNI-DS v8

Published Nov 14, 2023

Click board™

Accel Click

Development board



NECTO Studio



Enhance your projects with accurate motion detection, capturing its speed and direction with precision



Hardware Overview

How does it work?

Accel Click is based on the ADXL345, a complete 3-axis acceleration measurement system that operates at low power consumption levels from Analog Devices. It measures both dynamic accelerations, resulting from motion or shock, and static acceleration, such as gravity, and allows selectable full-scale acceleration measurements in ranges of ±2g, ±4g, ±8g, or ±16g with a resolution of 4mg/LSB on the ±2g range. Acceleration is reported digitally, communicating via the SPI or the I2C protocol and providing 16-bit output resolution. Its high resolution also enables the measurement of inclination changes less than 1.0°. The ADXL345 supports several special sensing functions. Activity and inactivity sensing detect the presence or lack

of motion by comparing the acceleration on any axis with user-set thresholds, while tap sensing detects single and double taps in any direction. Besides, a free-fall sensing feature detects if the device is falling. All these functions can be mapped to the interrupt pin routed on the INT pin of the mikroBUS™ socket. Accel Click allows the use of both I2C and SPI interfaces. The selection can be made by positioning SMD jumpers labeled as COMM SEL in an appropriate position. 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 ADXL345 allows choosing the least significant bit (LSB) of its I2C slave address using the SMD jumper labeled ADDR

SEL. An integrated memory management system with a 32-level first in, first out (FIFO) buffer can store data to minimize host processor activity and lower overall system power consumption. Low power modes enable intelligent motion-based power management with threshold sensing and active acceleration measurement at low power dissipation. 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 Click hardware overview image

Features overview

Development board

UNI-DS v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR MCUs regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. 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, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it 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

HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. UNI-DS 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.

UNI-DS v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation



MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

SPI Select / ID COMM
SPI Clock
Power Supply
I2C Clock
I2C Data

Take a closer look


Accel Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI-DS v8 as your development board.

Fusion for PIC v8 front image hardware assembly
Buck 22 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
v8 SiBRAIN MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Accel Click driver.

Key functions:

  • accel_read_x_axis - This function reads X axis value from Accel

  • accel_read_y_axis - This function reads Y axis value from Accel

  • accel_read_z_axis - This function reads Z axis value from Accel

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 Accel Click example
 * # Description
 * This example demonstrates the use of Accel click board by reading and
 * displaying the accelerometer data (X, Y, and Z axis).
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes SPI/I2C driver and settings data read format,
 * power mode, FIFO control and baud rate ( 100Hz default ).
 * ## Application Task
 * Reads X, Y and Z axis and logs on usbuart every 100 ms.
 * \author Jovan Stajkovic
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "accel.h"

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

static accel_t accel;
static log_t logger;

static uint8_t tmp;
static int16_t val_x;
static int16_t val_y;
static int16_t val_z;

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

void application_init ( void )
    log_cfg_t log_cfg;
    accel_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 " );

    accel_cfg_setup( &cfg );
    accel_init( &accel, &cfg );

    accel_generic_read( &accel, ACCEL_REG_DEVID, &tmp, 1 );

    if ( tmp == ACCEL_DEVID )
        log_printf( &logger, "---- Comunication OK!!! ----\r\n" );
        log_printf( &logger, "---- Comunication ERROR!!! ----\r\n" );
        for ( ; ; );
    accel_default_cfg ( &accel );

void application_task ( void )
    val_x = accel_read_x_axis( &accel );
    log_printf( &logger, "Axis X : %.3f g\r\n", val_x / ACCEL_DATA_RES_LSB_PER_G );

    val_y = accel_read_y_axis( &accel );
    log_printf( &logger, "Axis Y : %.3f g\r\n", val_y / ACCEL_DATA_RES_LSB_PER_G );

    val_z = accel_read_z_axis( &accel );
    log_printf( &logger, "Axis Z : %.3f g\r\n", val_z / ACCEL_DATA_RES_LSB_PER_G );

    log_printf( &logger, "-------------------\r\n" );
    Delay_ms( 100 );

int main ( void ) 
    application_init( );
    for ( ; ; ) 
        application_task( );

    return 0;

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

Additional Support