Beginner
10 min

Embrace the future of stretch force measurement using PIC32MZ2048EFM100

From flex to facts

Stretch Click with Curiosity PIC32 MZ EF

Published Jul 22, 2025

Click board™

Stretch Click

Dev. board

Curiosity PIC32 MZ EF

Compiler

NECTO Studio

MCU

PIC32MZ2048EFM100

Revolutionize applications across industries by harnessing conductive rubber cords to accurately measure and optimize stretch forces for enhanced design and performance

A

A

Hardware Overview

How does it work?

Stretch Click is based on the circuitry that allows measuring the stretch forces of the 2mm diameter conductive rubber cord. In a "relaxed" state, the resistance is about 130 ohms per centimeter. The resistance increases as you stretch it out (the particles get further apart); for example, a 15cm piece is proportional to 2.1k ohms (25cm long stretch is 26/15*2.1K = 3.5k ohms). You can stretch the rubber about 50-70% longer than the resting length, so a 15cm piece shouldn't be stretched more than 25cm. Once the force is released, the rubber will shrink back, although it's not very

"fast" and it takes a minute or two to revert to its original length. The resistance of the cord increases when stretched, impacting the reverse voltage on the voltage divider, which can be measured. The Stretch Click allows stretch force readings to be available on an analog AN pin of the mikroBUS™ socket. It's not a true linear sensor, and the resistance may vary from batch to batch, so we consider it a way to measure stretching motion, but it isn't really precise. In addition, this Click board™ features a user-configurable LED1 light-emitting diode that can

visually represent the measured force. This LED1 can be controlled over the PWM pin of the mikroBUS™ socket. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the J1 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.

Stretch Click hardware overview image

Features overview

Development board

Curiosity PIC32 MZ EF development board is a fully integrated 32-bit development platform featuring the high-performance PIC32MZ EF Series (PIC32MZ2048EFM) that has a 2MB Flash, 512KB RAM, integrated FPU, Crypto accelerator, and excellent connectivity options. It includes an integrated programmer and debugger, requiring no additional hardware. Users can expand

functionality through MIKROE mikroBUS™ Click™ adapter boards, add Ethernet connectivity with the Microchip PHY daughter board, add WiFi connectivity capability using the Microchip expansions boards, and add audio input and output capability with Microchip audio daughter boards. These boards are fully integrated into PIC32’s powerful software framework, MPLAB Harmony,

which provides a flexible and modular interface to application development a rich set of inter-operable software stacks (TCP-IP, USB), and easy-to-use features. The Curiosity PIC32 MZ EF development board offers expansion capabilities making it an excellent choice for a rapid prototyping board in Connectivity, IOT, and general-purpose applications.

Curiosity PIC32MZ EF double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC32

MCU Memory (KB)

2048

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

524288

Used MCU Pins

mikroBUS™ mapper

Analog Output
RPB4
AN
NC
NC
RST
SPI Chip Select
RPD4
CS
SPI Clock
RPD1
SCK
SPI Data OUT
RPD14
MISO
SPI Data IN
RPD3
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
External Sync
RPE8
PWM
Interrupt
RF13
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Stretch Click Schematic schematic

Step by step

Project assembly

Curiosity PIC32MZ EF front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity PIC32 MZ EF as your development board.

Curiosity PIC32MZ EF front image hardware assembly
GNSS2 Click front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
Board mapper by product7 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
Curiosity PIC32 MZ EF MCU Step 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

Software Support

Library Description

This library contains API for Stretch Click driver.

Key functions:

  • stretch_cfg_setup - Config Object Initialization function

  • stretch_turn_on_led - Turn on the LED function

  • stretch_turn_off_led -Turn off the LED function

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 Stretch Click example
 * 
 * # Description
 * The application is for stretch measuring 
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver enables GPIO and ADC, turn off the LED and starts write log. 
 * 
 * ## Application Task  
 * This is a example which demonstrates the use of Stretch Click board. Stretch Click reads and display ADC value.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "stretch.h"

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

static stretch_t stretch;
static log_t logger;

// ------------------------------------------------------- ADDITIONAL FUNCTIONS


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

void application_init ( void )
{
    log_cfg_t log_cfg;
    stretch_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.

    stretch_cfg_setup( &cfg );
    STRETCH_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    stretch_init( &stretch, &cfg );

    Delay_100ms();

    log_printf( &logger, "------------------- \r\n" );
    log_printf( &logger, "  Stretch  Click  "  );
    log_printf( &logger, "-------------------\r\n" );

    stretch_turn_off_led( &stretch );
    Delay_100ms( );

    log_printf( &logger, " ADC Initializated " );
    log_printf( &logger, "-------------------" );
}

void application_task ( void )
{
    stretch_data_t tmp;
    
    //  Task implementation.
    
    tmp = stretch_generic_read ( &stretch );
    log_printf( &logger, "** ADC value : [DEC]- %d, [HEX]- 0x%x \r\n", tmp, tmp );
    Delay_ms ( 1000 );

    Delay_100ms( );
    
    if ( tmp < 500 )
    {
        stretch_turn_on_led( &stretch );
    }
        
    else
    {
        stretch_turn_off_led( &stretch );
    }

    log_printf( &logger, " Resistance : %d \r\n", tmp );
    log_printf( &logger, "-------------------\r\n" );
    Delay_1sec( );
}

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

Additional Support

Resources

Love this project?

'Buy This Kit' button takes you directly to the shopping cart where you can easily add or remove products.