10 min

Unlock a new level of flexibility in resistance setting with TPL0501 and STM32F439ZG

Control a voltage with digital signals

DIGI POT 2 Click with Fusion for ARM v8

Published Aug 21, 2023

Click board™

DIGI POT 2 Click

Development board

Fusion for ARM v8


NECTO Studio



Enhance signal conditioning and gain control with our digital potentiometer, ensuring accurate and rapid adjustments in a digitally connected world



Hardware Overview

How does it work?

DIGI POT 2 Click is based on the TPL0501, a 256-taps, single-channel, digital potentiometer with an SPI interface from Texas Instruments. The TPL0501 can be used as a three-terminal potentiometer or a two-terminal rheostat. It has four screw terminals: A High terminal (H), a Low terminal (L), and two Wiper terminals (W), internally connected. The H and L terminals do not have polarity restrictions; H can be a higher voltage than L and vice-versa. The position of the wiper (W) terminal is controlled by the value in the 8-bit wiper resistance register. There are two functional

modes for the DIGI POT 2 Click. When all three terminals are used, the TPL0501 generates a voltage divider, where the voltage divider at wiper-to-H and wiper-to-L is proportional to the input voltage at H to L. It operates in rheostat mode as a variable resistor when only two terminals are used. Depending on the polarity, the variable resistance can be anywhere between the H and L terminals. In this case, the nominal resistance between H and L terminals is 10KΩ, and the TPL0501 has 256 tap positions of the wiper. DIGI POT 2 Click communicates with the host MCU using the

3-wire SPI serial interface as a write-only. The SCK timing frequency maximum is 25MHz. 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.

DIGI POT 2 Click top side image
DIGI POT 2 Click bottom side image

Features overview

Development board

Fusion for ARM 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 ARM® Cortex®-M based 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, Fusion for ARM v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the Fusion for ARM 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. Fusion for ARM 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.

Fusion for ARM v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

SPI Chip Select
SPI Clock
Power Supply
Power Supply

Take a closer look


DIGI POT 2 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 Fusion for ARM v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN Access 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 DIGI POT 2 Click driver.

Key functions:

  • digipot2_set_wiper_positions - The function sets 8-bit wiper positions data

  • digipot2_convert_output - The function convert 10-bit ADC value to volatage reference

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 main.c
 * @brief DigiPot2 Click example
 * # Description
 * The demo application changes the resistance using DIGI POT 2 Click.
 * The demo application is composed of two sections :
 * ## Application Init
 * Initializes SPI and LOG modules.
 * ## Application Task
 * This is an example which demonstrates the use of DIGI POT 2 Click board.
 * Increments the wiper position by 10 positions every 5 seconds.
 * @author Stefan Ilic

#include "board.h"
#include "log.h"
#include "digipot2.h"

static digipot2_t digipot2;
static log_t logger;

uint8_t wiper_pos;

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    digipot2_cfg_t digipot2_cfg;  /**< Click config object. */

     * 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.

    digipot2_cfg_setup( &digipot2_cfg );
    DIGIPOT2_MAP_MIKROBUS( digipot2_cfg, MIKROBUS_1 );
    err_t init_flag  = digipot2_init( &digipot2, &digipot2_cfg );
    if ( SPI_MASTER_ERROR == init_flag ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );

    log_printf( &logger, "----------------\r\n" );
    log_printf( &logger, " DIGI POT 2 Click\r\n" );
    log_printf( &logger, "----------------\r\n" );

void application_task ( void ) {
    for ( uint16_t n_cnt = 127; n_cnt < 255; n_cnt += 10 ) {
        wiper_pos = ( uint8_t ) n_cnt;
        digipot2_set_wiper_positions( &digipot2, wiper_pos );
        Delay_ms( 5000 );

void main ( void ) {
    application_init( );

    for ( ; ; ) {
        application_task( );

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

Additional Support