Beginner
10 min

Make a unique navigation solution with L80 and PIC18LF4458

Easily chart your course with utmost simplicity

GPS3 Click with EasyPIC v7

Published Nov 01, 2023

Click board™

GPS3 Click

Dev. board

EasyPIC v7

Compiler

NECTO Studio

MCU

PIC18LF4458

Unleash the boundless potential of navigation technology, revolutionizing the way people explore and navigate

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Hardware Overview

How does it work?

GPS3 Click is based on the L80, a GPS receiver module with a patch antenna equipped with an MTK positioning engine from Quectel. With an embedded LNA at a nominal frequency of 1575.42MHz, the L80 receives an L1 band signal from the GPS satellites. This module uses 66 search channels and 22 simultaneous tracking channels, making it possible to track and find satellites within the shortest time, even when the signal is in a signal-challenging environment. The embedded flash memory stores useful navigation data and performs updates. The L80 communicates with the host MUC using the UART interface with commonly used UART RX and TX

pins as its communication protocol operating at 9600bps. In addition, there is an RST pin for resetting the device. The GPS 3 Click also features a VBAT connector for connecting a battery for the RTC domain, which helps lower the power consumption. Regarding battery usage, the VCC-BCKP solder jumper should be removed. While the current date and time are transmitted in NMEA sentences (UTC), a precise and accurate timing signal is provided and indicated using a red LED indicator marked as PPS. The GPS 3 Click also features the u.FL connector for connecting the appropriate active antenna offered by MIKROE for improved range and received signal strength.

The antenna detection and switching functions will handle the connecting source without a hassle while keeping positioning. The detection result, notification, and statuses of the antennas will also be included in the NMEA message. This Click board™ can only be operated from a 3.3V logic voltage level. Therefore, the board must perform appropriate logic voltage conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

GPS3 Click hardware overview 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)

24

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

2048

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Reset
RE1
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
UART TX
RC6
TX
UART RX
RC7
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

GPS3 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
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
EasyPIC v7 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 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

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 GPS3 Click driver.

Key functions:

  • gps3_generic_read - This function reads a desired number of data bytes by using UART serial interface

  • gps3_clear_ring_buffers - This function clears UART TX and RX ring buffers

  • gps3_parse_gpgga - This function parses the GPGGA data from the read response buffer

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 GPS 3 Click Example.
 *
 * # Description
 * This example demonstrates the use of GPS 3 Click by reading and displaying
 * the GPS coordinates.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and logger.
 *
 * ## Application Task
 * Reads the received data, parses the GPGGA info from it, and once it receives the position fix
 * it will start displaying the coordinates on the USB UART.
 *
 * ## Additional Function
 * - static void gps3_clear_app_buf ( void )
 * - static err_t gps3_process ( gps3_t *ctx )
 * - static void gps3_parser_application ( char *rsp )
 * 
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "gps3.h"
#include "string.h"

#define PROCESS_BUFFER_SIZE 200

static gps3_t gps3;
static log_t logger;

static char app_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;

/**
 * @brief GPS 3 clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @return None.
 * @note None.
 */
static void gps3_clear_app_buf ( void );

/**
 * @brief GPS 3 data reading function.
 * @details This function reads data from device and concatenates data to application buffer.
 * @param[in] ctx : Click context object.
 * See #gps3_t object definition for detailed explanation.
 * @return @li @c  0 - Read some data.
 *         @li @c -1 - Nothing is read.
 * See #err_t definition for detailed explanation.
 * @note None.
 */
static err_t gps3_process ( gps3_t *ctx );

/**
 * @brief GPS 3 parser application function.
 * @details This function parses GNSS data and logs it on the USB UART. It clears app and ring buffers
 * after successfully parsing data.
 * @param[in] ctx : Click context object.
 * See #gps3_t object definition for detailed explanation.
 * @param[in] rsp Response buffer.
 * @return None.
 * @note None.
 */
static void gps3_parser_application ( gps3_t *ctx, char *rsp );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    gps3_cfg_t gps3_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.
    gps3_cfg_setup( &gps3_cfg );
    GPS3_MAP_MIKROBUS( gps3_cfg, MIKROBUS_1 );
    if ( UART_ERROR == gps3_init( &gps3, &gps3_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    if ( GPS3_OK == gps3_process( &gps3 ) )
    {
        if ( PROCESS_BUFFER_SIZE == app_buf_len )
        {
            gps3_parser_application( &gps3, app_buf );
        }
    }
}

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;
}

static void gps3_clear_app_buf ( void ) 
{
    memset( app_buf, 0, app_buf_len );
    app_buf_len = 0;
}

static err_t gps3_process ( gps3_t *ctx ) 
{
    char rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t rx_size = 0;
    rx_size = gps3_generic_read( ctx, rx_buf, PROCESS_BUFFER_SIZE );
    if ( rx_size > 0 ) 
    {
        int32_t buf_cnt = app_buf_len;
        if ( ( ( app_buf_len + rx_size ) > PROCESS_BUFFER_SIZE ) && ( app_buf_len > 0 ) ) 
        {
            buf_cnt = PROCESS_BUFFER_SIZE - ( ( app_buf_len + rx_size ) - PROCESS_BUFFER_SIZE );
            memmove ( app_buf, &app_buf[ PROCESS_BUFFER_SIZE - buf_cnt ], buf_cnt );
        }
        for ( int32_t rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) 
        {
            if ( rx_buf[ rx_cnt ] ) 
            {
                app_buf[ buf_cnt++ ] = rx_buf[ rx_cnt ];
                if ( app_buf_len < PROCESS_BUFFER_SIZE )
                {
                    app_buf_len++;
                }
            }
        }
        return GPS3_OK;
    }
    return GPS3_ERROR;
}

static void gps3_parser_application ( gps3_t *ctx, char *rsp )
{
    char element_buf[ 100 ] = { 0 };
    if ( GPS3_OK == gps3_parse_gpgga( rsp, GPS3_GPGGA_LATITUDE, element_buf ) )
    {
        static uint8_t wait_for_fix_cnt = 0;
        if ( strlen( element_buf ) > 0 )
        {
            log_printf( &logger, "\r\n Latitude: %.2s degrees, %s minutes \r\n", element_buf, &element_buf[ 2 ] );
            gps3_parse_gpgga( rsp, GPS3_GPGGA_LONGITUDE, element_buf );
            log_printf( &logger, " Longitude: %.3s degrees, %s minutes \r\n", element_buf, &element_buf[ 3 ] );
            memset( element_buf, 0, sizeof( element_buf ) );
            gps3_parse_gpgga( rsp, GPS3_GPGGA_ALTITUDE, element_buf );
            log_printf( &logger, " Altitude: %s m \r\n", element_buf );
            wait_for_fix_cnt = 0;
        }
        else
        {
            if ( wait_for_fix_cnt % 5 == 0 )
            {
                log_printf( &logger, " Waiting for the position fix...\r\n\n" );
                wait_for_fix_cnt = 0;
            }
            wait_for_fix_cnt++;
        }
        gps3_clear_ring_buffers( ctx );
        gps3_clear_app_buf( );
    }
}

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

Additional Support

Resources

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