Intermediate
30 min

Ensure reliable and consistent movement data in your motion tracking and control systems with TCUT1800X01 and PIC18F47K42

A new era in rotation encoding

Opto Encoder 3 Click with EasyPIC v8

Published Sep 23, 2023

Click board™

Opto Encoder 3 Click

Dev. board

EasyPIC v8

Compiler

NECTO Studio

MCU

PIC18F47K42

Experience the benefits of real-time, high-resolution motion feedback

A

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Hardware Overview

How does it work?

Opto Encoder 3 Click is based on the TCUT1800X01, a tall dome quad channel transmissive optical sensor with phototransistor outputs from Vishay Semiconductor. This sensor is equipped with one infrared LED with the wavelength of 950nm, and four phototransistors. These phototransistors are positioned behind small slits on the sensor, on the opposite side of the LED. They form four separate channels. When the transistors get illuminated by the LED, they become conductive. The collectors of these transistors are connected to the same pin, while their emitters are routed to separate output pins of the TCUT1800X01 - E1, E2 E3, and E4. This allows the activity on each channel to be detected by the host MCU separately. Since the signals of these output channels are not enough to drive pins on a

host MCU, the Click board™ features two additional buffer IC – the SN74LVC125A, from texas instruments. E1, E2, E3, and E4 pins are routed to the input pins od the buffer IC. These pins are pulled to a LOW logic level by the pull-down resistors, to avoid floating. The output pins of the buffer are routed to the mikroBUS™ AN, RST, INT, and PWM pins respectively. Signal encoding itself is done by the host MCU. Having four optical sensing channels, Opto Encoder 3 click has the ability of both speed and direction encoding. The most common usage is encoding of the step motor position: a cylinder with slits is physically mounted above the sensor so that the LED can illuminate the phototransistors only through these slits. By rotating this cylinder, the light beam will be blocked periodically. The single sensor output

will be a pulse train, while the cylinder is rotating. Having two photo sensors physically distanced by a small amount, allows the pulse signal of the first sensor to be either delayed or expedited with respect to the pulse on the second sensor, depending on the rotational direction. By adding two more sensors, the resolution and reliability of the position reading are further increased. This Click board™ can be operated only with a 5V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Opto Encoder 3 Click top side image
Opto Encoder 3 Click bottom side 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

PIC18F47K42

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

8192

Used MCU Pins

mikroBUS™ mapper

Encoder Output 1
RA2
AN
Encoder Output 2
RE1
RST
Enable
RE0
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Encoder Output 4
RC0
PWM
Encoder Output 3
RB0
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Opto Encoder 3 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
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
EasyPIC v8 Access DIPMB 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 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 Opto Encoder 3 Click driver.

Key functions:

  • optoencoder3_cnt - Functions for reading number of swipes

  • optoencoder3_enable - Sets state of click

  • optoencoder3_read_all_pins - Sets state of all pins

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 Opto Encoder 3 Click example
 * 
 * # Description
 * The demo application displays the counter value or displays the status of each O pins.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Configures the driver and logger, and selects the demo application mode.
 * 
 * ## Application Task  
 * Depending on the demo application mode set in the application init it:
 *    - Measures and displays the value of the counter - DEMO_CNT mode; or
 *    - Draws the status of each O pin - DEMO_GRAPH mode.
 * 
 * \author Luka Filipovic
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "optoencoder3.h"

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

static optoencoder3_t optoencoder3;
static log_t logger;

optoencoder3_pins_t pins;
static uint8_t example_setter;
static uint8_t old_state = 0xFF;
static uint8_t state = 0;

// ------------------------------------------------------------------ MACRO

#define DEMO_CNT    1
#define DEMO_GRAPH  2

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

void draw_pins_status( void )
{
    optoencoder3_read_all_pins( &optoencoder3, &pins );

    state = pins.pin_o1 | ( pins.pin_o2 << 1 ) | ( pins.pin_o3 << 2 ) | ( pins.pin_o4 << 3 );
    
    if ( old_state != state )
    {
        log_printf( &logger, "-Pins status:\r\n" );
        
        if ( pins.pin_o1 == OPTOENCODER3_PIN_ACTIVE )
        {
            log_printf( &logger, "*  " );
        }
        else
        {
            log_printf( &logger, "o  " );
        }

        if ( pins.pin_o3 == OPTOENCODER3_PIN_ACTIVE )
        {
            log_printf( &logger, "*\r\n" );
        }
        else
        {
            log_printf( &logger, "o\r\n" );
        }

        if ( pins.pin_o2 == OPTOENCODER3_PIN_ACTIVE )
        {
            log_printf( &logger, "*  " );
        }
        else
        {
            log_printf( &logger, "o  " );
        }

        if ( pins.pin_o4 == OPTOENCODER3_PIN_ACTIVE )
        {
            log_printf( &logger, "*" );
        }
        else
        {
            log_printf( &logger, "o" );
        }

        log_printf( &logger, "\r\n" );
    }
    
    old_state = state;
}

void view_counters ( void )
{
    uint8_t cnt;
    int8_t swipe_cnt;
    
    cnt = optoencoder3_cnt( &optoencoder3 );
    swipe_cnt = optoencoder3_dir_cnt( &optoencoder3 );
    
    if ( old_state != cnt )
    {
        log_printf( &logger, "---Counter number of swipes and direction counter:\r\n" );
        log_printf( &logger, "* Counter : %d \r\n", ( uint16_t ) cnt );
        log_printf( &logger, "* Direction counter : %d \r\n", ( int16_t ) swipe_cnt );
        log_printf( &logger, " _________________________________\r\n\r\n\r\n" );
    }
    
    old_state = cnt;
}

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    optoencoder3_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.

    optoencoder3_cfg_setup( &cfg );
    OPTOENCODER3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    optoencoder3_init( &optoencoder3, &cfg );

    optoencoder3_enable ( &optoencoder3, OPTOENCODER3_ENABLE );
    
    example_setter = DEMO_CNT;
}

void application_task ( void )
{
    if ( example_setter == DEMO_GRAPH )
    {
        draw_pins_status(  );
    }
    else if ( example_setter == DEMO_CNT )
    {
        view_counters(  );
    }
}

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

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