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Provide accurate positioning information with EVA-M8M-0 and PIC18F4682

Explore with confidence: Key to the most reliable location services

GNSS 11 Click with EasyPIC v7a

Published Nov 01, 2023

Click board™

GNSS 11 Click

Dev.Board

EasyPIC v7a

Compiler

NECTO Studio

MCU

PIC18F4682

Receive signals from satellites in space to determine their precise location on Earth

A

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Hardware Overview

How does it work?

GNSS 11 Click is based on the EVA-M8M, a concurrent GNSS module from u-blox. It can process up to three GNSS and be configured for a single GNSS operation using GPS, GLONASS, or BeiDou and disable QZSS and SBAS. The module can be configured to receive any single GNSS constellation or any set of permissible combinations according to the table from the datasheet. Galileo is not enabled as the default configuration. There are several features that EVA-M8M brings to you, such as assisted GNSS (AssistNow™ online/offline/autonomous), augmentation systems (SBAS), Differential GPS, odometer, data logging, geofencing, spoofing detection, and more. GNSS 11 Click can use the SPI, I2C, or UART interface to communicate with the host MCU, which can be selected over the five COMM SEL jumpers. By default, UART and I2C are selected. The I2C is actually a DDC interface (I2C compliant) and can be operated in slave mode only, supporting a clock frequency of up to 400kHz. If you choose an SPI interface, you can count on 125kbps and 5.5MHz of clock frequency. There are several pins on the mikroBUS™ socket that you can also use. The module can be reset over the RST pin. The antenna can be turned on over the ANT pin, which enables the TPS2041B, a current-limited power distribution switch

from Texas Instruments. This switch feeds the power to an antenna, and if the output load exceeds the current-limit threshold or a short is present, the switch will limit the output current and notify the host MCU over the OC pin. The EVA-M8M module also provides an SQI interface for optional external flash for future firmware upgrades and improved A-GNSS performance. This flash can be used for the AssitNowTM Offline feature to store the orbit data, for data logging, and more. Worth mentioning is that without the external flash, only GPS satellites are used, and the prediction time decreases to three days. The SQI flash can be connected over the SQI header. This Click board™ comes equipped with a USB type C connector (2.0 FS), which can be used for communication as an alternative to the UART. In addition, thanks to the additional electronics on the board, this Click can also work in a standalone configuration, where the appropriate power supply voltage is provided by USB. The u-blox USB (CDC-ACM) driver supports Windows 7 and 8 operating systems, while for Windows 10, it is not required as it has a built-in USB serial driver. However, plugging initially into an internet-connected Windows 10 PC will download the u-blox combined sensor and VCP driver package. The interrupt INT pin can be used to control the

receiver or for aid. GNSS 11 Click possesses the SMA antenna connector with an impedance of 50Ω, which can connect the appropriate active antenna for improved range and received signal strength. The EVA-M8M module has a backup supply option on this Click board™ available as an onboard VCC input or over the coin battery. You can choose the backup source over the V BCKP switch. The time output pulse is available as a PPS LED indication. There are also several test pads on GNSS 11 Click. The EVA-M8M supports an active antenna supervisor, which enables the receiver to detect short circuits at the active antenna and antenna presence detection. The pads ANT_OFF, ANT_OK, and ANT_DET serve for testing purposes of this feature. The SAFEBOOT pad allows you to test the state of the module while entering the Safe Boot Mode, which is used for programming the flash memory in production or recovering a corrupted flash memory. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. 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.

GNSS 11 Click  hardware overview image

Features overview

Development board

EasyPIC v7a is the seventh generation of PIC development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 8-bit PIC microcontrollers from Microchip and has a broad set of unique functions, such as the first-ever embedded debugger/programmer over USB-C. 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 v7a allows you to connect accessory boards, sensors, and custom electronics more efficiently than ever. Each part of the EasyPIC v7a 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 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-C (USB-C) 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 v7a 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 v7a double side image

Microcontroller Overview

MCU Card / MCU

PIC18F4682

Architecture

PIC

MCU Memory (KB)

80

Silicon Vendor

Microchip

Pin count

40

RAM (Bytes)

3328

You complete me!

Accessories

GNSS Active External Antenna is a unique multi-band type of antenna coming from u-blox that is the perfect selection for high precision GNSS applications, which require highly accurate location abilities such as RTK. The ANN-MB-00 is a multi-band (L1, L2/E5b/B2I) active GNSS antenna with a 5m cable and SMA connector. The antenna supports GPS, GLONASS, Galileo, and BeiDou and includes a high-performance multi-band RHCP dual-feed patch antenna element, a built-in high-gain LNA with SAW pre-filtering, and a 5 m antenna cable with SMA connector, and is waterproof.

GNSS 11 Click accessories image

Used MCU Pins

mikroBUS™ mapper

Overcurrent Output
RA2
AN
Reset / ID SEL
RE1
RST
SPI Select / ID COMM
RE0
CS
SPI Clock
RC3
SCK
SPI Data OUT
RC4
MISO
SPI Data IN
RC5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Antenna Enable
RC0
PWM
Interrupt
RB0
INT
UART TX
RC6
TX
UART RX
RC7
RX
I2C Clock
RC3
SCL
I2C Data
RC4
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

GNSS 11 Click Schematic schematic

Step by step

Project assembly

EasyPIC v7a front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyPIC v7a as your development board.

EasyPIC v7a front image hardware assembly
GNSS2 Click front image hardware assembly
MCU DIP 40 hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
EasyPIC v7a 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

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 GNSS 11 Click driver.

Key functions:

  • gnss11_reset_device - This function resets the device by toggling the RST and ANT_ON pins.

  • gnss11_generic_read - This function reads a desired number of data bytes by using UART serial interface.

  • gnss11_parse_gga - This function parses the GGA data from the read response buffer.

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 GNSS 11 Click Example.
 *
 * # Description
 * This example demonstrates the use of GNSS 11 click by reading and displaying
 * the GNSS coordinates.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and resets the click board.
 *
 * ## Application Task
 * Reads the received data, parses the NMEA GGA info from it, and once it receives 
 * the position fix it will start displaying the coordinates on the USB UART.
 *
 * ## Additional Function
 * - static void gnss11_clear_app_buf ( void )
 * - static void gnss11_log_app_buf ( void )
 * - static err_t gnss11_process ( gnss11_t *ctx )
 * - static void gnss11_parser_application ( uint8_t *rsp )
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "gnss11.h"

// Application buffer size
#define APP_BUFFER_SIZE             500
#define PROCESS_BUFFER_SIZE         200

static gnss11_t gnss11;
static log_t logger;

static uint8_t app_buf[ APP_BUFFER_SIZE ] = { 0 };
static int32_t app_buf_len = 0;

/**
 * @brief GNSS 11 clearing application buffer.
 * @details This function clears memory of application buffer and reset its length.
 * @note None.
 */
static void gnss11_clear_app_buf ( void );

/**
 * @brief GNSS 11 log application buffer.
 * @details This function logs data from application buffer to USB UART.
 * @note None.
 */
static void gnss11_log_app_buf ( void );

/**
 * @brief GNSS 11 data reading function.
 * @details This function reads data from device and concatenates data to application buffer. 
 * @param[in] ctx : Click context object.
 * See #gnss11_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 gnss11_process ( gnss11_t *ctx );

/**
 * @brief GNSS 11 parser application.
 * @param[in] rsp Response buffer.
 * @details This function logs GNSS data on the USB UART.
 * @return None.
 * @note None.
 */
static void gnss11_parser_application ( uint8_t *rsp );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    gnss11_cfg_t gnss11_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.
    gnss11_cfg_setup( &gnss11_cfg );
    GNSS11_MAP_MIKROBUS( gnss11_cfg, MIKROBUS_1 );
    if ( GNSS11_OK != gnss11_init( &gnss11, &gnss11_cfg ) )
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    gnss11_reset_device ( &gnss11 );
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    gnss11_process( &gnss11 );
    if ( app_buf_len > ( sizeof ( GNSS11_RSP_GGA ) + GNSS11_GGA_ELEMENT_SIZE ) ) 
    {
        gnss11_parser_application( app_buf );
    }
}

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

    return 0;
}

static void gnss11_clear_app_buf ( void ) 
{
    memset( app_buf, 0, app_buf_len );
    app_buf_len = 0;
}

static void gnss11_log_app_buf ( void )
{
    for ( int32_t buf_cnt = 0; buf_cnt < app_buf_len; buf_cnt++ )
    {
        log_printf( &logger, "%c", app_buf[ buf_cnt ] );
    }
}

static err_t gnss11_process ( gnss11_t *ctx ) 
{
    uint8_t rx_buf[ PROCESS_BUFFER_SIZE ] = { 0 };
    int32_t overflow_bytes = 0;
    int32_t rx_cnt = 0;
    int32_t rx_size = 0;
    if ( GNSS11_DRV_SEL_UART == ctx->drv_sel )
    {
        rx_size = gnss11_generic_read( ctx, rx_buf, PROCESS_BUFFER_SIZE );
    }
    else if ( ( GNSS11_DRV_SEL_I2C == ctx->drv_sel ) || ( GNSS11_DRV_SEL_SPI == ctx->drv_sel ) )
    {
        if ( GNSS11_OK == gnss11_generic_read( ctx, rx_buf, 1 ) )
        {
            if ( GNSS11_DUMMY != rx_buf[ 0 ] )
            {
                rx_size = 1;
            }
        }
    }
    if ( ( rx_size > 0 ) && ( rx_size <= APP_BUFFER_SIZE ) ) 
    {
        if ( ( app_buf_len + rx_size ) > APP_BUFFER_SIZE ) 
        {
            overflow_bytes = ( app_buf_len + rx_size ) - APP_BUFFER_SIZE;
            app_buf_len = APP_BUFFER_SIZE - rx_size;
            memmove ( app_buf, &app_buf[ overflow_bytes ], app_buf_len );
            memset ( &app_buf[ app_buf_len ], 0, overflow_bytes );
        }
        for ( rx_cnt = 0; rx_cnt < rx_size; rx_cnt++ ) 
        {
            if ( rx_buf[ rx_cnt ] ) 
            {
                app_buf[ app_buf_len++ ] = rx_buf[ rx_cnt ];
            }
        }
        return GNSS11_OK;
    }
    return GNSS11_ERROR;
}

static void gnss11_parser_application ( uint8_t *rsp )
{
    uint8_t element_buf[ 100 ] = { 0 };
    if ( GNSS11_OK == gnss11_parse_gga( rsp, GNSS11_GGA_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 ] );
            memset( element_buf, 0, sizeof( element_buf ) );
            gnss11_parse_gga( rsp, GNSS11_GGA_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 ) );
            gnss11_parse_gga( rsp, GNSS11_GGA_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++;
        }
        gnss11_clear_app_buf(  );
    }
}

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

Additional Support

Resources