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Unlock a new level of flexibility in resistance setting with TPL0501 and PIC18F25K42

Control a voltage with digital signals

DIGI POT 2 Click with EasyPIC v7

Published Nov 01, 2023

Click board™

DIGI POT 2 Click

Development board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18F25K42

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

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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

EasyPIC v7 is the seventh generation of PIC development boards specially designed to develop embedded applications rapidly. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB-B. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyPIC v7 allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of

the EasyPIC v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use various external power sources, including an external 12V power supply, 7-23V AC or 9-32V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B) connector. Communication options such as

USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from PIC10F, PIC12F, PIC16F, PIC16Enh, PIC18F, PIC18FJ, and PIC18FK families. EasyPIC v7 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.

EasyPIC v7 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
SPI Chip Select
RA5
CS
SPI Clock
RC3
SCK
NC
NC
MISO
SPI Data IN
RC5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
2

Take a closer look

Schematic

DIGI POT 2 Click Schematic schematic

Step by step

Project assembly

EasyPIC v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7 as your development board.

EasyPIC v7 front image hardware assembly
LTE IoT 5 Click front image hardware assembly
MCU DIP 28 hardware assembly
LTE IoT 5 Click complete accessories setup image hardware assembly
EasyPIC v7 Access MB 2 - 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 DIP image step 7 hardware assembly
EasyPIC PRO v7a Display Selection Necto Step 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

Resources