{"id":443,"date":"2025-03-14T17:10:02","date_gmt":"2025-03-14T17:10:02","guid":{"rendered":"https:\/\/alphahex.com.br\/?p=443"},"modified":"2025-03-20T19:52:45","modified_gmt":"2025-03-20T19:52:45","slug":"lendo-coordenadas-gps-direto-da-pagina-nmea-esp32-plataformio","status":"publish","type":"post","link":"https:\/\/alphahex.com.br\/en\/lendo-coordenadas-gps-direto-da-pagina-nmea-esp32-plataformio\/","title":{"rendered":"GPS coordinates directly from the NMEA page with ESP32 and PlataformIO"},"content":{"rendered":"\n

Neste artigo vou demonstrar como coletar coordenadas de GPS direto da p\u00e1gina NMEA<\/strong> (National Marine Electronics Association). Esse formato \u00e9 um padr\u00e3o utilizado para a comunica\u00e7\u00e3o de dados de navega\u00e7\u00e3o e posi\u00e7\u00e3o de sistemas GPS.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Os dados enviados pelo GPS para a porta serial geralmente consistem em v\u00e1rias senten\u00e7as (strings de texto) no formato NMEA, com informa\u00e7\u00f5es sobre a posi\u00e7\u00e3o, hor\u00e1rio, velocidade, dire\u00e7\u00e3o e outros par\u00e2metros. Cada senten\u00e7a NMEA come\u00e7a com um caractere “$”<\/strong> e \u00e9 seguida por informa\u00e7\u00f5es que s\u00e3o separadas por v\u00edrgulas.<\/p>\n\n\n\n

Aqui est\u00e1 um exemplo de uma senten\u00e7a NMEA t\u00edpica enviada por um m\u00f3dulo GPS:<\/p>\n\n\n\n

$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47<\/p>\n\n\n\n

Com o hardware configurado, este simples c\u00f3digo e um m\u00f3dulo GPS conectado ao ESP32, voc\u00ea ver\u00e1 no terminal o mesmo conte\u00fado mostrado na foto acima:<\/p>\n\n\n\n

<\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
void<\/span> <\/span>loop<\/span>() {<\/span><\/span>\n  <\/span>while<\/span> (<\/span>Serial2<\/span>.<\/span>available<\/span>()) {<\/span><\/span>\n    <\/span>char<\/span> c = <\/span>Serial2<\/span>.<\/span>read<\/span>();<\/span><\/span>\n    <\/span>Serial<\/span>.<\/span>print<\/span>(c);<\/span><\/span>\n  }<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
Neste tutorial, vamos criar uma Task em FreeRTOS que realiza a leitura cont\u00ednua de dados selecionados nesta p\u00e1gina, permitindo seu uso em qualquer aplica\u00e7\u00e3o.<\/strong><\/p>\n\n\n\n
Para isso, vamos utilizar um m\u00f3dulo de desenvolvimento ESP32 S3 WROOM -1 e um m\u00f3dulo GPS da Ublox Neo M7. No entanto funciona com qualquer ESP32 e m\u00f3dulo de GPS:<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
    \n
  • VCC do GPS<\/strong> \u2192 3.3V do ESP32-S3<\/strong><\/li>\n\n\n\n
  • GND do GPS<\/strong> \u2192 GND do ESP32-S3<\/strong><\/li>\n\n\n\n
  • TX do GPS<\/strong> \u2192 RX2 (GPIO16) do ESP32-S3<\/strong><\/li>\n\n\n\n
  • RX do GPS<\/strong> \u2192 TX2 (GPIO17) do ESP32-S3<\/strong><\/li>\n<\/ul>\n\n\n\n
    Conectando o ESP ao Note e Criando o Projeto no VS Code<\/strong><\/p>\n\n\n\n
    Ap\u00f3s conectar o ESP32<\/strong> ao GPS<\/strong>, voc\u00ea pode agora conect\u00e1-lo ao seu computador usando um cabo USB<\/strong>.<\/p>\n\n\n\n
    \ud83d\udccc Criando o Projeto no VS Code com PlatformIO<\/h3>\n\n\n\n
    1\ufe0f\u20e3 Abra o VS Code<\/strong> e v\u00e1 at\u00e9 o PlatformIO<\/strong>.
    2\ufe0f\u20e3 Clique em Criar Novo Projeto<\/strong>.
    3\ufe0f\u20e3 Durante a configura\u00e7\u00e3o, selecione:<\/p>\n\n\n\n
      \n
    • Modelo do ESP<\/strong> que est\u00e1 utilizando.<\/li>\n\n\n\n
    • Framework: Arduino<\/strong>.<\/li>\n<\/ul>\n\n\n\n
      Se estiver seguindo este tutorial e usando o mesmo modelo de ESP, seu arquivo platformio.ini<\/strong> ficar\u00e1 assim:<\/p>\n\n\n\n
      [env:esp32-s3-devkitc-1]
      platform = espressif32
      board = esp32-s3-devkitc-1
      framework = arduino
      monitor_speed = 115200
      upload_speed = 921600<\/p>\n\n\n\n
      Conforme mencionado acima o objetivo deste projeto \u00e9 receber as senten\u00e7as NMEA de um receptor GPS e extrair as coordenadas de latitude, longitude, altitude e outros dados relevantes. As coordenadas s\u00e3o armazenadas em uma estrutura de dados e constantemente atualizadas, com a possibilidade de us\u00e1-las em outras fun\u00e7\u00f5es do sistema.<\/p>\n\n\n\n
      Estrutura do Projeto<\/h3>\n\n\n\n
        \n
      1. Coleta das senten\u00e7as GPS NMEA.<\/strong><\/li>\n\n\n\n
      2. Processamento de cada senten\u00e7a para extrair dados como latitude, longitude, velocidade, etc.<\/strong><\/li>\n\n\n\n
      3. Valida\u00e7\u00e3o das senten\u00e7as usando a verifica\u00e7\u00e3o de checksum.<\/strong><\/li>\n\n\n\n
      4. Uso de FreeRTOS para garantir que a coleta de dados seja feita continuamente, sem bloquear a execu\u00e7\u00e3o do c\u00f3digo.<\/strong><\/li>\n<\/ol>\n\n\n\n
        1. Inicialmente vamos declarar as fun\u00e7\u00f5es que ser\u00e3o utilizadas no projeto<\/h2>\n\n\n\n
        <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
        #include<\/span> <\/span><Arduino.h><\/span><\/span>\n<\/span>\n#define<\/span> NUM_SENTENCAS 3<\/span><\/span>\n<\/span>\n\/\/ --- Function Declarations ---<\/span><\/span>\n<\/span>\nString<\/span> <\/span>seqRetData<\/span>(<\/span>String<\/span> <\/span>*<\/span>SEQ<\/span>, <\/span>uint8_t<\/span> <\/span>pos<\/span>);<\/span>      \/\/ Returns the isolated data from the sequence based on the requested position<\/span><\/span>\nbool<\/span> <\/span>gpsSetData<\/span>();<\/span>                                \/\/ GPS Sets GPS data with processed sentences <\/span><\/span>\nvoid<\/span> <\/span>gpsTask<\/span>(<\/span>void<\/span> <\/span>*<\/span>pvParameters<\/span>);<\/span>                 \/\/ Task function to continuously collect GPS sentences<\/span><\/span>\nbool<\/span> <\/span>nmea0183_checksum<\/span>(<\/span>const<\/span> <\/span>char<\/span> <\/span>*<\/span>nmea_data<\/span>);<\/span>    \/\/ Verifies if the checksum of an NMEA0183 sentence is correct<\/span><\/span>\n<\/span>\n\/\/ -----------------------------<\/span><\/span>\n<\/span><\/code><\/pre>
        Expand<\/span><\/div><\/div>\n\n\n\n
        2. Declara\u00e7\u00e3o de Vari\u00e1veis e Estruturas<\/h2>\n\n\n\n
        Na sequ\u00eancia, declaramos uma estrutura Datagps<\/code> que armazenar\u00e1 os dados coletados, como latitude, longitude, n\u00famero de sat\u00e9lites, e outros par\u00e2metros do GPS. Abaixo est\u00e1 a defini\u00e7\u00e3o dessa estrutura:<\/p>\n\n\n\n
        <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
        \/\/ --- GPS Data Structure ---<\/span><\/span>\ntypedef<\/span> <\/span>struct<\/span><\/span>\n{<\/span><\/span>\n  <\/span>float<\/span>     lat;  <\/span><\/span>\n  <\/span>float<\/span>     lon; <\/span><\/span>\n  <\/span>uint8_t<\/span>   fix; <\/span><\/span>\n  <\/span>uint8_t<\/span>   sat; <\/span><\/span>\n  <\/span>float<\/span>     hdop;<\/span><\/span>\n  <\/span>float<\/span>     alt; <\/span><\/span>\n  <\/span>float<\/span>     vel; <\/span><\/span>\n  <\/span>float<\/span>     bea;  <\/span><\/span>\n  <\/span>char<\/span>      <\/span>hor<\/span>[<\/span>7<\/span>];<\/span><\/span>\n  <\/span>char<\/span>      <\/span>date<\/span>[<\/span>7<\/span>]; <\/span><\/span>\n  <\/span>char<\/span>      <\/span>isfix<\/span>[<\/span>2<\/span>];<\/span><\/span>\n  <\/span>bool<\/span>      isnew = <\/span>false<\/span>;   <\/span><\/span>\n  <\/span>bool<\/span>      isvalid = <\/span>false<\/span>; <\/span><\/span>\n}  <\/span>Datagps<\/span>;<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
        3. Vari\u00e1veis Globais<\/h2>\n\n\n\n
        Aqui, temos vari\u00e1veis que armazenam os dados das senten\u00e7as GPS e da estrutura Datagps<\/code> que mant\u00e9m os dados atualizados. Observe que \u00e9 na vari\u00e1vel “sentenca” que declaramos de quais senten\u00e7as da p\u00e1gina NMEA vamos retirar as informa\u00e7\u00f5es.<\/p>\n\n\n\n
        <\/p>\n\n\n\n
        <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
        \/\/ --- Global Variables ---<\/span><\/span>\n<\/span>\nDatagps gps;<\/span>  \/\/ GPS Data<\/span><\/span>\n<\/span>\nString <\/span>sentenca<\/span>[NUM_SENTENCAS] = {<\/span>"$GPGGA"<\/span>, <\/span>"$GPVTG"<\/span>, <\/span>"$GPRMC"<\/span>};<\/span><\/span>\nString <\/span>sentData<\/span>[NUM_SENTENCAS];<\/span>                               \/\/ Data for each sentence<\/span><\/span>\nbool<\/span> <\/span>sentencaValida<\/span>[NUM_SENTENCAS] = {<\/span>false<\/span>, <\/span>false<\/span>, <\/span>false<\/span>};<\/span>   \/\/ Flag to validate if the sentence was received and is correct<\/span><\/span>\n<\/span>\n\/\/ --------------------------------------------------------------<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
        4. Configura\u00e7\u00e3o Inicial do Setup()<\/code><\/h2>\n\n\n\n
        A fun\u00e7\u00e3o setup()<\/code> \u00e9 respons\u00e1vel pela inicializa\u00e7\u00e3o do sistema, configura\u00e7\u00e3o da comunica\u00e7\u00e3o serial e pela cria\u00e7\u00e3o da tarefa FreeRTOS<\/strong> para ler continuamente as senten\u00e7as GPS.<\/p>\n\n\n\n
        <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
        void<\/span> <\/span>setup<\/span>() {<\/span><\/span>\n  <\/span>Serial<\/span>.<\/span>begin<\/span>(<\/span>115200<\/span>);<\/span><\/span>\n  <\/span>delay<\/span>(<\/span>100<\/span>);<\/span><\/span>\n  <\/span>Serial2<\/span>.<\/span>begin<\/span>(<\/span>9600<\/span>, SERIAL_8N1, <\/span>16<\/span>, <\/span>17<\/span>);<\/span><\/span>\n  <\/span>delay<\/span>(<\/span>100<\/span>);<\/span><\/span>\n  <\/span>Serial<\/span>.<\/span>println<\/span>(<\/span>"NMEA GPS Sentence Example v1.0"<\/span>);  <\/span><\/span>\n<\/span>\n  <\/span>xTaskCreate<\/span>(gpsTask, <\/span>"GPS Task"<\/span>, <\/span>2048<\/span>, <\/span>NULL<\/span>, <\/span>1<\/span>, <\/span>NULL<\/span>);<\/span>   \/\/ Adjust stack size as needed<\/span><\/span>\n<\/span>\n  \/\/ Set to get new data<\/span><\/span>\n  <\/span>gps<\/span>.<\/span>isnew<\/span> = <\/span>false<\/span>;<\/span><\/span>\n  <\/span>gps<\/span>.<\/span>isvalid<\/span> = <\/span>false<\/span>;<\/span><\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
        Aqui, configuramos a comunica\u00e7\u00e3o serial tanto para o debug do ESP32 quanto para o receptor GPS conectado ao pino Serial2.<\/p>\n\n\n\n
        5. Loop Principal <\/h2>\n\n\n\n
        Dentro da fun\u00e7\u00e3o loop()<\/code>, chamamos a fun\u00e7\u00e3o gpsSetData()<\/code> que \u00e9 respons\u00e1vel por verificar se h\u00e1 novos dados e armazen\u00e1-los na estrutura Datagps<\/code>.<\/p>\n\n\n\n
        <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
        void<\/span> <\/span>loop<\/span>() {<\/span><\/span>\n<\/span>\n  \/\/ Get GPS data from NMEA sentences<\/span><\/span>\n  <\/span>gpsSetData<\/span>();<\/span><\/span>\n  <\/span>delay<\/span>(<\/span>1000<\/span>);<\/span><\/span>\n<\/span>\n}<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
        6. Tarefa FreeRTOS <\/h2>\n\n\n\n
        A fun\u00e7\u00e3o gpsTask()<\/code> \u00e9 uma tarefa criada pelo FreeRTOS para continuamente coletar os dados do GPS sem bloquear o fluxo principal do programa. Nela, monitoramos a comunica\u00e7\u00e3o serial, lemos e isolamos os dados enviados pelo GPS, e verificamos se a senten\u00e7a recebida \u00e9 v\u00e1lida utilizando a fun\u00e7\u00e3o de checksum<\/strong>. <\/p>\n\n\n\n
        Lembrando que l\u00e1 no in\u00edcio do c\u00f3digo selecionamos as senten\u00e7as que queremos isolar na p\u00e1gina NMEA atrav\u00e9s da declara\u00e7\u00e3o da seguinte vari\u00e1vel:<\/p>\n\n\n\n
        <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
        String <\/span>sentenca<\/span>[NUM_SENTENCAS] = {<\/span>"$GPGGA"<\/span>, <\/span>"$GPVTG"<\/span>, <\/span>"$GPRMC"<\/span>};<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
        Fun\u00e7\u00e3o da Task FreeRtos:<\/h3>\n\n\n\n
        <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
        \/\/ --- Task function to continuously collect GPS sentences ---<\/span><\/span>\nvoid<\/span> <\/span>gpsTask<\/span>(<\/span>void<\/span> <\/span>*<\/span>pvParameters<\/span>) {<\/span><\/span>\n  <\/span>char<\/span> <\/span>buffer<\/span>[<\/span>512<\/span>];<\/span>             \/\/ Buffer for serial reading<\/span><\/span>\n  <\/span>int<\/span> bufferIndex = <\/span>0<\/span>;<\/span>          \/\/ Buffer index<\/span><\/span>\n  String tempBuffer = <\/span>""<\/span>;<\/span>       \/\/ Accumulator for serial data<\/span><\/span>\n  String currentSentence = <\/span>""<\/span>;<\/span>  \/\/ Current sentence being read<\/span><\/span>\n<\/span>\n<\/span>\n  \/\/ Initialize with sentences not validated<\/span><\/span>\n  <\/span>for<\/span> (<\/span>int<\/span> i = <\/span>0<\/span>; i < <\/span>3<\/span>; i++) {<\/span><\/span>\n    <\/span>sentencaValida<\/span>[i] = <\/span>false<\/span>;<\/span><\/span>\n  }<\/span><\/span>\n<\/span>\n  <\/span>while<\/span> (<\/span>true<\/span>) {<\/span><\/span>\n    \/\/ If there is data available on the serial<\/span><\/span>\n    <\/span>if<\/span> (<\/span>Serial2<\/span>.<\/span>available<\/span>() > <\/span>0<\/span>) {<\/span><\/span>\n      \/\/ Continuous reading of serial data<\/span><\/span>\n      <\/span>while<\/span> (<\/span>Serial2<\/span>.<\/span>available<\/span>()) {<\/span><\/span>\n        <\/span>char<\/span> incomingByte = <\/span>Serial2<\/span>.<\/span>read<\/span>();<\/span>  \/\/ Reads the next byte<\/span><\/span>\n        tempBuffer += incomingByte;<\/span>   \/\/ Accumulates the read bytes<\/span><\/span>\n        \/\/ If we find the end of a sentence, like '\\n'<\/span><\/span>\n        <\/span>if<\/span> (incomingByte == <\/span>'<\/span>\\n<\/span>'<\/span>) {          <\/span><\/span>\n          \/\/ Serial.println(tempBuffer);<\/span><\/span>\n          \/\/ For each requested sentence, check if it was found in the buffer<\/span><\/span>\n          <\/span>for<\/span> (<\/span>int<\/span> i = <\/span>0<\/span>; i < <\/span>3<\/span>; i++) {<\/span><\/span>\n            \/\/ Check if the sentence was found<\/span><\/span>\n            <\/span>if<\/span> (<\/span>tempBuffer<\/span>.<\/span>startsWith<\/span>(<\/span>sentenca<\/span>[i]) && !<\/span>sentencaValida<\/span>[i]) {<\/span><\/span>\n              \/\/ Stores the validated sentence<\/span><\/span>\n              <\/span>if<\/span> (<\/span>nmea0183_checksum<\/span>(<\/span>tempBuffer<\/span>.<\/span>c_str<\/span>())) {<\/span><\/span>\n                <\/span>sentData<\/span>[i] = tempBuffer;<\/span>  \/\/ Stores the complete sentence<\/span><\/span>\n                <\/span>sentencaValida<\/span>[i] = <\/span>true<\/span>;<\/span>  \/\/ Marks as valid<\/span><\/span>\n                <\/span>Serial<\/span>.<\/span>print<\/span>(<\/span>"Senten\u00e7a "<\/span> + <\/span>sentenca<\/span>[i] + <\/span>" v\u00e1lida recebida: "<\/span> + tempBuffer);<\/span><\/span>\n              } <\/span>else<\/span> {<\/span><\/span>\n                <\/span>Serial<\/span>.<\/span>println<\/span>(<\/span>"Erro de checksum na senten\u00e7a: "<\/span> + <\/span>sentenca<\/span>[i]);<\/span><\/span>\n              }<\/span><\/span>\n            }<\/span><\/span>\n          }<\/span><\/span>\n          tempBuffer = <\/span>""<\/span>;<\/span>  \/\/ Clears the buffer after processing<\/span><\/span>\n        }<\/span><\/span>\n      }<\/span><\/span>\n    }<\/span><\/span>\n    <\/span><\/span>\n    \/\/ Check if all sentences were received<\/span><\/span>\n    <\/span>bool<\/span> allValid = <\/span>true<\/span>;<\/span><\/span>\n    <\/span>for<\/span> (<\/span>int<\/span> i = <\/span>0<\/span>; i < <\/span>3<\/span>; i++) {<\/span><\/span>\n      <\/span>if<\/span> (!<\/span>sentencaValida<\/span>[i]) {<\/span><\/span>\n        allValid = <\/span>false<\/span>;<\/span><\/span>\n        <\/span>break<\/span>;<\/span><\/span>\n      }<\/span><\/span>\n    }<\/span><\/span>\n<\/span>\n    \/\/ If all sentences are valid, restart reading<\/span><\/span>\n    <\/span>if<\/span> (allValid) {<\/span><\/span>\n      \/\/ Serial.println("Todas as senten\u00e7as v\u00e1lidas foram recebidas!");<\/span><\/span>\n      <\/span>gps<\/span>.<\/span>isnew<\/span> = <\/span>true<\/span>;<\/span><\/span>\n      \/\/ Reset variables if necessary<\/span><\/span>\n      <\/span>for<\/span> (<\/span>int<\/span> i = <\/span>0<\/span>; i < <\/span>3<\/span>; i++) {<\/span><\/span>\n        <\/span>sentencaValida<\/span>[i] = <\/span>false<\/span>;<\/span><\/span>\n      }<\/span><\/span>\n    }<\/span><\/span>\n    <\/span><\/span>\n    <\/span>vTaskDelay<\/span>(<\/span>100<\/span> \/ portTICK_PERIOD_MS);<\/span> \/\/ Delay to avoid processor overload<\/span><\/span>\n  }<\/span><\/span>\n}<\/span> \/\/ --- END Task function to continuously collect GPS sentences ---<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
        Explica\u00e7\u00e3o da L\u00f3gica<\/h2>\n\n\n\n