Beginner
10 min

Integrate a rotary knob and visual indication into electronic projects with TLC5925 and PIC18F25K80

User-friendly and visually informative input interface

Rotary B 2 Click with EasyPIC v8

Published Nov 01, 2023

Click board™

Rotary B 2 Click

Dev. board

EasyPIC v8

Compiler

NECTO Studio

MCU

PIC18F25K80

Make your projects easier to use by adding a simple knob and clear visuals for better interaction

A

A

Hardware Overview

How does it work?

Rotary B 2 Click is based on the TLC5925, a low-power 16-channel constant-current LED sink driver from Texas Instruments that, combined with a high-quality rotary encoder from ALPS, the EC12D1564402, allows you to add a precision input knob to your design. The EC12D1564402 incremental rotary encoder is surrounded by a ring of 16 blue LEDs where a single rotation is divided into 15 discrete steps (in contrast to a potentiometer, a rotary encoder can be spun around continuously). The driver can control each LED individually, allowing various lighting effects to be programmed. The encoder outputs A and B signals (out of phase to each other) on the two mikroBUS™ lines, alongside the knob

push-button feature, which outputs through the interrupt line. The EC12D1564402 is a 15-pulse incremental rotary encoder with a push button. This encoder has unique mechanical specifications (debouncing time for its internal switches goes down to 2ms), and it can withstand a huge number of switching cycles, up to 30.000. The supporting debouncing circuitry allows contacts to settle before the output is triggered fully. Rotary B 2 Click uses a standard 4-wire SPI serial interface of the TLC5925 LED driver to communicate with the host MCU supporting clock frequency of up to 30MHz. Rotating the encoder, it outputs A and B signals (out of phase to each other) on the two mikroBUS™ lines, ENA and ENB

pins of the mikroBUS™ socket, alongside the push-button contact, which outputs through the SW pin (interrupt line) of the mikroBUS™ socket. Two SN74LVC1T45 single-bit dual-supply bus transceivers from Texas Instruments are used for logic-level translation. 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.

Rotary B 2 Click hardware overview image

Features overview

Development board

EasyPIC v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports many high pin count 8-bit PIC microcontrollers from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer. 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, EasyPIC v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the EasyPIC v8 development board contains the components necessary for the most efficient operation of the same board. In addition to the advanced integrated CODEGRIP programmer/debugger module, which offers many valuable programming/debugging options and seamless integration with the Mikroe software environment, the board 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 DEVICE, and CAN are also included, including the well-established mikroBUS™ standard, two display options (graphical and character-based LCD), and several different DIP sockets. These sockets cover a wide range of 8-bit PIC MCUs, from the smallest PIC MCU devices with only eight up to forty pins. EasyPIC 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.

EasyPIC v8 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

3648

Used MCU Pins

mikroBUS™ mapper

Encode Output B
RA3
AN
ID SEL
RA0
RST
SPI Select / ID COMM
RA5
CS
SPI Clock
RC3
SCK
SPI Data OUT
RC4
MISO
SPI Data IN
RC5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Encoder Output A
RC1
PWM
Switch Output
RB1
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

Click board™ Schematic

Rotary B 2 Click Schematic schematic

Step by step

Project assembly

EasyPIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v8 as your development board.

EasyPIC v8 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 v8 28pin-DIP Access - 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
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

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 Rotary B 2 Click driver.

Key functions:

  • rotaryb2_set_led_pos - This function turns on the LED for the selected LED position.

  • rotaryb2_set_led_data - This function, using SPI serial interface, writes a desired 16-bit data.

  • rotaryb2_get_state_switch - This function return rotary encoder switch signal, states of the SW(INT).

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 Rotary B 2 Click example
 *
 * # Description
 * This library contains the API for the Rotary B 2 Click driver 
 * to control LEDs states and a rotary encoder position readings.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization of SPI module and log UART.
 * After the driver init, the app executes a default configuration and turn off all LEDs.
 *
 * ## Application Task
 * This example demonstrates the use of the Rotary B 2 Click board.
 * The demo example shows the functionality of a rotary encoder used to control LEDs.
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "rotaryb2.h"

#define ROTARYB2_ONE_LED          ROTARYB2_SET_LED_DATA_1
#define ROTARYB2_TWO_LED          ROTARYB2_SET_LED_DATA_1  | ROTARYB2_SET_LED_DATA_9
#define ROTARYB2_FOUR_LED         ROTARYB2_SET_LED_DATA_1  | ROTARYB2_SET_LED_DATA_5  | \
                                  ROTARYB2_SET_LED_DATA_9  | ROTARYB2_SET_LED_DATA_13 
#define ROTARYB2_EIGHT_LED        ROTARYB2_SET_LED_DATA_1  | ROTARYB2_SET_LED_DATA_3  | \
                                  ROTARYB2_SET_LED_DATA_5  | ROTARYB2_SET_LED_DATA_7  | \
                                  ROTARYB2_SET_LED_DATA_9  | ROTARYB2_SET_LED_DATA_11 | \
                                  ROTARYB2_SET_LED_DATA_13 | ROTARYB2_SET_LED_DATA_15
#define ROTARYB2_EIGHT_LED_INV    ROTARYB2_SET_LED_DATA_2  | ROTARYB2_SET_LED_DATA_4  | \
                                  ROTARYB2_SET_LED_DATA_6  | ROTARYB2_SET_LED_DATA_8  | \
                                  ROTARYB2_SET_LED_DATA_10 | ROTARYB2_SET_LED_DATA_12 | \
                                  ROTARYB2_SET_LED_DATA_14 | ROTARYB2_SET_LED_DATA_16

static rotaryb2_t rotaryb2;
static log_t logger;

static uint8_t start_rot_status = 0;
static uint8_t led_demo_state = 0;
static uint8_t old_state = 0;
static uint8_t new_state = 1;
static uint8_t old_rot_state = 0;
static uint8_t new_rot_state = 1;
static uint16_t led_data = 1;

/**
 * @brief Rotary B 2 select LED demo data function.
 * @details This function selects one of the four LED demo data 
 * based on the current state of the LED demo.
 * @return LED demo data:
 *         @li @c 0x0001 (ROTARYB2_ONE_LED)   - Turn ON LED[1],
 *         @li @c 0x0101 (ROTARYB2_TWO_LED)   - Turn ON LED[1,9],
 *         @li @c 0x0101 (ROTARYB2_FOUR_LED)  - Turn ON LED[1,5,9,13],
 *         @li @c 0x5555 (ROTARYB2_EIGHT_LED) - Turn ON LED[1,3,5,7,9,11,13,15].
 */
static uint16_t rotaryb2_sel_led_demo_data ( uint8_t led_demo_state );

/**
 * @brief Rotary B 2 switch detection function.
 * @details This function is used for the switch state detection.
 * @return Nothing.
 */
static void rotaryb2_switch_detection ( void );

/**
 * @brief Rotary B 2 encoder mechanism function.
 * @details This function is used to control the state of the LEDs 
 * by detecting the rotation direction of the rotary encoder.
 * @return Nothing.
 */
static void rotaryb2_encoder_mechanism ( void );

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    rotaryb2_cfg_t rotaryb2_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.
    rotaryb2_cfg_setup( &rotaryb2_cfg );
    ROTARYB2_MAP_MIKROBUS( rotaryb2_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == rotaryb2_init( &rotaryb2, &rotaryb2_cfg ) )
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( ROTARYB2_ERROR == rotaryb2_default_cfg ( &rotaryb2 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void )
{
    if ( ROTARYB2_OK == rotaryb2_set_led_data( &rotaryb2, led_data ) )
    {
        rotaryb2_switch_detection( );
        rotaryb2_encoder_mechanism( );
    }
}

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

    return 0;
}

static uint16_t rotaryb2_sel_led_demo_data ( uint8_t led_demo_state ) 
{
    switch ( led_demo_state ) 
    {
        case 0: 
        {
            return ROTARYB2_ONE_LED;
            break;
        }
        case 1: 
        {
            return ROTARYB2_TWO_LED;
            break;
        }
        case 2: 
        {
            return ROTARYB2_FOUR_LED;
            break;
        }
        case 3: 
        {
            return ROTARYB2_EIGHT_LED;
            break;
        }
        default: 
        {
            return ROTARYB2_ONE_LED;
            break;
        }
    }
}

static void rotaryb2_switch_detection ( void )
{
    if ( rotaryb2_get_state_switch( &rotaryb2 ) ) 
    {
        new_state = 1;
        if ( (  1 == new_state ) && ( 0 == old_state ) ) 
        {
            old_state = 1;
            led_demo_state = ( led_demo_state + 1 ) % 5;
            if ( 4 == led_demo_state ) 
            {
                for ( uint8_t n_cnt = 0; n_cnt < 10; n_cnt++ )
                {
                    rotaryb2_set_led_data( &rotaryb2, ROTARYB2_EIGHT_LED_INV );
                    Delay_ms( 100 );
                    rotaryb2_set_led_data( &rotaryb2, ROTARYB2_EIGHT_LED );
                    Delay_ms( 100 );
                }
                
                for ( uint8_t led_p = ROTARYB2_SET_LED_POS_1; led_p <= ROTARYB2_SET_LED_POS_16; led_p++ ) 
                {
                    rotaryb2_set_led_pos( &rotaryb2, led_p );
                    Delay_ms( 100 );
                }
                
                led_demo_state = 0;
                led_data = rotaryb2_sel_led_demo_data( led_demo_state );
            }
            else 
            {
                led_data = rotaryb2_sel_led_demo_data( led_demo_state );
            }
        }
    }
    else 
    {
        old_state = 0;
    }
}

static void rotaryb2_encoder_mechanism ( void )
{
    if ( rotaryb2_get_state_ena( &rotaryb2 ) == rotaryb2_get_state_enb( &rotaryb2 ) ) 
    {
        old_rot_state = 0;
        start_rot_status = rotaryb2_get_state_ena( &rotaryb2 ) && rotaryb2_get_state_enb( &rotaryb2 );
    }
    else 
    {
        new_rot_state = 1;
        if ( new_rot_state != old_rot_state ) 
        {
            old_rot_state = 1;
            if ( start_rot_status != rotaryb2_get_state_ena( &rotaryb2 ) ) 
            {
                led_data = ( led_data << 1 ) | ( led_data >> 15 );
            }
            else 
            {
                led_data = ( led_data >> 1 ) | ( led_data << 15 );
            }
        }
    }
}

// ------------------------------------------------------------------------ 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.