Intermediate
30 min

Explore the flexibility of digital potentiometer with AD5175 and STM32F031K6

Experience smooth digital voltage control

DIGI POT 7 Click with Nucleo 32 with STM32F031K6 MCU

Published Oct 01, 2024

Click board™

DIGI POT 7 Click

Dev. board

Nucleo 32 with STM32F031K6 MCU

Compiler

NECTO Studio

MCU

STM32F031K6

Facilitate precise control and adjustment of resistance values in a wide range of applications

A

A

Hardware Overview

How does it work?

DIGI POT 7 Click is based on the AD5175, a single-channel 1024-position digital rheostat, with less than ±1% end-to-end resistor tolerance error and a 50-time programmable (50-TP) wiper memory from Analog Devices. It possesses one RDAC register that determines the resistor Wiper position and acts as a scratchpad register allowing unlimited resistance settings. The RDAC register can be programmed with any position set using the serial interface. When a desirable Wiper position is found, this value can be stored in a 50-TP memory register. Besides, the Wiper position is always restored to that position for subsequent Power-Up. The storing of 50-TP data takes approximately 350 ms, and during this time, the AD5175 is locked and doesn't acknowledge any new command preventing any changes from taking place. The nominal resistance between terminal W and terminal A is 10kΩ with 1024-tap

points accessed by the Wiper terminal, while in the Zero-Scale condition, a total Wiper resistance of 120Ω is present. The 10-bit data inside the RDAC register is decoded to select one of the 1024 possible Wiper settings. The AD5175 also provides the possibility of the Shutdown feature by executing the software shutdown command. This feature places the RDAC register in a Zero-Power-Consumption state where terminal A is disconnected from the Wiper terminal. The AD5175 can be removed from Shutdown Mode by executing Software Shutdown Command or performing the Hardware Reset feature. DIGI POT 7 click communicates with MCU using the standard I2C 2-Wire interface, with a clock frequency up to 100kHz in the Standard and 400kHz in the Fast Mode. Besides, it also allows the choice of the least significant bit (LSB) of its I2C slave address by positioning the SMD jumper

labeled as ADDR SEL to an appropriate position marked as 0 and 1. This Click board™ can be reset via software by calling the Reset command that loads the RDAC register with the contents of the most recently programmed 50-TP memory location. This register loads with mid-scale if no 50-TP memory location has been previously programmed. It also can be reset through the Hardware Reset pin, labeled as RST on the mikroBUS™ socket, by putting this pin in a logic low state. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC 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 7 Click hardware overview image

Features overview

Development board

Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The

board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,

and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.

Nucleo 32 with STM32F031K6 MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

32

Silicon Vendor

STMicroelectronics

Pin count

32

RAM (Bytes)

4096

You complete me!

Accessories

Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.

Click Shield for Nucleo-32 accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Reset
PA11
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PB6
SCL
I2C Data
PB7
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

DIGI POT 7 Click Schematic schematic

Step by step

Project assembly

Click Shield for Nucleo-144 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo 32 with STM32F031K6 MCU as your development board.

Click Shield for Nucleo-144 front image hardware assembly
Nucleo 144 with STM32L4A6ZG MCU front image hardware assembly
Stepper 22 Click front image hardware assembly
Prog-cut hardware assembly
Stepper 22 Click complete accessories setup image hardware assembly
Nucleo-32 with STM32 MCU 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 image step 5 hardware assembly
Necto image step 6 hardware assembly
STM32 M4 Clicker HA MCU/Select 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

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 DIGI POT 7 Click driver.

Key functions:

  • digipot7_hw_reset - Hardware reset function

  • digipot7_read_rdac - The function read a 10-bit RDAC data

  • digipot7_write_rdac - The function writes a 10-bit RDAC data

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 main.c
 * @brief DIGIPOT7 Click example
 *
 * # Description
 * This is an example that demonstrate the use of the DIGI POT 7 click board.
 * 
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization enables I2C, perform a hardware reset, enable write and set to normal operating mode, 
 * also write log.
 *
 * ## Application Task
 * In this example we set different resistance values:
 * 1.024 kOhm, 2.048 kOhm, 4.096 kOhm and 8.192 kOhm.
 * Results are being sent to the Usart Terminal where you can track their changes.
 * All data logs write on USB uart changes approximately for every 5 sec.
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "digipot7.h"

static digipot7_t digipot7;
static log_t logger;

void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    digipot7_cfg_t digipot7_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.
    digipot7_cfg_setup( &digipot7_cfg );
    DIGIPOT7_MAP_MIKROBUS( digipot7_cfg, MIKROBUS_1 );
    err_t init_flag = digipot7_init( &digipot7, &digipot7_cfg );
    if ( I2C_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, " Hardware Reset \r\n" );
    digipot7_hw_reset( &digipot7 );
    Delay_ms( 100 );
    
    log_printf( &logger, "----------------------------\r\n" );
    log_printf( &logger, " Enable Write \r\n" );
    digipot7_enable_write( &digipot7 );
    Delay_ms( 100 );
    
    log_printf( &logger, "----------------------------\r\n" );
    log_printf( &logger, " Set normal operating mode \r\n" );
    digipot7_operating_mode( &digipot7, DIGIPOT7_NORMAL_MODE );
    Delay_ms( 100 );
    
    log_printf( &logger, "----------------------------\r\n" );
    log_info( &logger, " Application Task " );
    log_printf( &logger, "----------------------------\r\n" );
}

void application_task ( void ) {
    log_printf( &logger, " Set Resistance: 1.024 kOhm \r\n" );
    log_printf( &logger, "----------------------------\r\n" );
    digipot7_set_resistance( &digipot7, 1024 );
    Delay_ms( 5000 );
    
    log_printf( &logger, " Set Resistance: 2.048 kOhm \r\n" );
    log_printf( &logger, "----------------------------\r\n" );
    digipot7_set_resistance( &digipot7, 2048 );
    Delay_ms( 5000 );
    
    log_printf( &logger, " Set Resistance: 4.096 kOhm \r\n" );
    log_printf( &logger, "----------------------------\r\n" );
    digipot7_set_resistance( &digipot7, 4096 );
    Delay_ms( 5000 );
    
    log_printf( &logger, " Set Resistance: 8.192 kOhm \r\n" );
    log_printf( &logger, "----------------------------\r\n" );
    digipot7_set_resistance( &digipot7, 8192 );
    Delay_ms( 5000 );
}

void main ( void ) {
    application_init( );

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

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

Additional Support

Resources

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