How to reverse std::string using std::reverse (C++)

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main(int argc, char** argv) {
    std::string s = "My string";
    // This reverses s in-place.
    std::reverse(std::begin(s), std::end(s));
    // Prints "gnirts yM"
    cout << s << endl;


Posted by Uli Köhler in C/C++

re2 C++ replace (GlobalReplace) minimal example

This minimal example shows how to replace strings using the re2 GlobalReplace() function:

#include <re2/re2.h>
#include <iostream>
#include <string>

using namespace re2;
using namespace std;

// Pre-compiled regex
RE2 myRegex("\\$[^\\$]+\\$");

int main(int argc, char** argv) {
    string myString = "This string $abc123$ contains two formulas $123 != 456$.";
    // NOTE: This will modify myString!
    RE2::GlobalReplace(&myString, myRegex, "FORMULA");
    // Prints "This string FORMULA contains two formulas FORMULA."
    cout << myString << endl;


Posted by Uli Köhler in C/C++

cpp-httplib: How to get query parameters

This example shows how to get a query parameter in cpp-httplib. See the cpp-httplib hello example for the full source code:

svr.Get("/hi", [](const httplib::Request& req, httplib::Response& res) {
    std::string id = req.get_param_value("id");
    res.set_content("id=" + id, "text/plain");

Access it at http://localhost:8080/hi?id=myid

and it will show you


id will be empty (== "") if no such parameter is given.

Posted by Uli Köhler in C/C++

How to fix Paho MQTT undefined reference to `SHA1_Init’


When trying to build your C++ application using Paho MQTT, you see a bunch of undefined reference error messages:

MQTTAsync.c:(.text+0x3482): undefined reference to `OpenSSL_version'
/usr/bin/ld: MQTTAsync.c:(.text+0x34a1): undefined reference to `OpenSSL_version'
/usr/bin/ld: MQTTAsync.c:(.text+0x34c0): undefined reference to `OpenSSL_version'
/usr/bin/ld: MQTTAsync.c:(.text+0x34df): undefined reference to `OpenSSL_version'
/usr/bin/ld: MQTTAsync.c:(.text+0x34fe): undefined reference to `OpenSSL_version'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(MQTTAsyncUtils.c.o): in function `MQTTAsync_closeOnly':
MQTTAsyncUtils.c:(.text+0x9b6): undefined reference to `SSL_SESSION_free'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(MQTTAsyncUtils.c.o): in function `MQTTAsync_receiveThread':
MQTTAsyncUtils.c:(.text+0x463b): undefined reference to `SSL_set_session'
/usr/bin/ld: MQTTAsyncUtils.c:(.text+0x5255): undefined reference to `SSL_get1_session'
/usr/bin/ld: MQTTAsyncUtils.c:(.text+0x55bb): undefined reference to `SSL_get1_session'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `call_ssl_psk_cb':
SSLSocket.c:(.text+0x11b): undefined reference to `SSL_get_SSL_CTX'
/usr/bin/ld: SSLSocket.c:(.text+0x129): undefined reference to `SSL_CTX_get_ex_data'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_error':
SSLSocket.c:(.text+0x1fa): undefined reference to `SSL_get_error'
/usr/bin/ld: SSLSocket.c:(.text+0x22d): undefined reference to `ERR_print_errors_cb'
/usr/bin/ld: SSLSocket.c:(.text+0x2f1): undefined reference to `ERR_get_error'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSL_CTX_info_callback':
SSLSocket.c:(.text+0x376): undefined reference to `SSL_alert_desc_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x381): undefined reference to `SSL_alert_type_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x3bc): undefined reference to `SSL_get_verify_result'
/usr/bin/ld: SSLSocket.c:(.text+0x411): undefined reference to `SSL_state_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x461): undefined reference to `SSL_get_current_cipher'
/usr/bin/ld: SSLSocket.c:(.text+0x469): undefined reference to `SSL_CIPHER_get_name'
/usr/bin/ld: SSLSocket.c:(.text+0x474): undefined reference to `SSL_state_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x4d1): undefined reference to `SSL_alert_desc_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x4dc): undefined reference to `SSL_alert_type_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x4e7): undefined reference to `SSL_state_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x503): undefined reference to `SSL_alert_desc_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x50e): undefined reference to `SSL_alert_type_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x541): undefined reference to `SSL_alert_desc_string_long'
/usr/bin/ld: SSLSocket.c:(.text+0x54c): undefined reference to `SSL_alert_type_string_long'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_initialize':
SSLSocket.c:(.text+0x8ee): undefined reference to `OPENSSL_init_ssl'
/usr/bin/ld: SSLSocket.c:(.text+0x90a): undefined reference to `OPENSSL_init_crypto'
/usr/bin/ld: SSLSocket.c:(.text+0x916): undefined reference to `OPENSSL_init_ssl'
/usr/bin/ld: SSLSocket.c:(.text+0x922): undefined reference to `OPENSSL_init_crypto'
/usr/bin/ld: SSLSocket.c:(.text+0xa11): undefined reference to `CRYPTO_get_ex_new_index'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_createContext':
SSLSocket.c:(.text+0xbee): undefined reference to `SSL_CTX_use_certificate_chain_file'
/usr/bin/ld: SSLSocket.c:(.text+0xc48): undefined reference to `SSL_CTX_set_default_passwd_cb'
/usr/bin/ld: SSLSocket.c:(.text+0xc55): undefined reference to `SSL_CTX_set_default_passwd_cb_userdata'
/usr/bin/ld: SSLSocket.c:(.text+0xc67): undefined reference to `SSL_CTX_use_PrivateKey_file'
/usr/bin/ld: SSLSocket.c:(.text+0xc9a): undefined reference to `SSL_CTX_load_verify_locations'
/usr/bin/ld: SSLSocket.c:(.text+0xce5): undefined reference to `SSL_CTX_set_default_verify_paths'
/usr/bin/ld: SSLSocket.c:(.text+0xd2e): undefined reference to `SSL_CTX_set_cipher_list'
/usr/bin/ld: SSLSocket.c:(.text+0xd56): undefined reference to `SSL_CTX_set_ex_data'
/usr/bin/ld: SSLSocket.c:(.text+0xd66): undefined reference to `SSL_CTX_set_psk_client_callback'
/usr/bin/ld: SSLSocket.c:(.text+0xd8f): undefined reference to `SSL_CTX_ctrl'
/usr/bin/ld: SSLSocket.c:(.text+0xdc5): undefined reference to `SSL_CTX_free'
/usr/bin/ld: SSLSocket.c:(.text+0xe51): undefined reference to `SSL_CTX_set_alpn_protos'
/usr/bin/ld: SSLSocket.c:(.text+0xeb9): undefined reference to `TLS_client_method'
/usr/bin/ld: SSLSocket.c:(.text+0xec1): undefined reference to `SSL_CTX_new'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_setSocketForSSL':
SSLSocket.c:(.text+0x1046): undefined reference to `SSL_CTX_set_info_callback'
/usr/bin/ld: SSLSocket.c:(.text+0x1056): undefined reference to `SSL_CTX_set_msg_callback'
/usr/bin/ld: SSLSocket.c:(.text+0x1075): undefined reference to `SSL_new'
/usr/bin/ld: SSLSocket.c:(.text+0x10ab): undefined reference to `SSL_get_cipher_list'
/usr/bin/ld: SSLSocket.c:(.text+0x10be): undefined reference to `SSL_set_fd'
/usr/bin/ld: SSLSocket.c:(.text+0x113b): undefined reference to `SSL_ctrl'
/usr/bin/ld: SSLSocket.c:(.text+0x121c): undefined reference to `SSL_CTX_set_verify'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_connect':
SSLSocket.c:(.text+0x12b7): undefined reference to `ERR_clear_error'
/usr/bin/ld: SSLSocket.c:(.text+0x12bf): undefined reference to `SSL_connect'
/usr/bin/ld: SSLSocket.c:(.text+0x135d): undefined reference to `SSL_get_peer_certificate'
/usr/bin/ld: SSLSocket.c:(.text+0x138c): undefined reference to `X509_check_host'
/usr/bin/ld: SSLSocket.c:(.text+0x13d4): undefined reference to `CRYPTO_free'
/usr/bin/ld: SSLSocket.c:(.text+0x13f6): undefined reference to `X509_free'
/usr/bin/ld: SSLSocket.c:(.text+0x144d): undefined reference to `X509_check_ip_asc'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_getch':
SSLSocket.c:(.text+0x1569): undefined reference to `ERR_clear_error'
/usr/bin/ld: SSLSocket.c:(.text+0x1579): undefined reference to `SSL_read'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_destroyContext':
SSLSocket.c:(.text+0x1630): undefined reference to `SSL_CTX_free'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_close':
SSLSocket.c:(.text+0x16b8): undefined reference to `ERR_clear_error'
/usr/bin/ld: SSLSocket.c:(.text+0x16c1): undefined reference to `SSL_shutdown'
/usr/bin/ld: SSLSocket.c:(.text+0x16ce): undefined reference to `SSL_free'
/usr/bin/ld: SSLSocket.c:(.text+0x16fd): undefined reference to `SSL_CTX_free'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_putdatas':
SSLSocket.c:(.text+0x191f): undefined reference to `ERR_clear_error'
/usr/bin/ld: SSLSocket.c:(.text+0x1930): undefined reference to `SSL_write'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_getdata':
SSLSocket.c:(.text+0x1ca5): undefined reference to `ERR_clear_error'
/usr/bin/ld: SSLSocket.c:(.text+0x1cb8): undefined reference to `SSL_read'
/usr/bin/ld: SSLSocket.c:(.text+0x1d7f): undefined reference to `SSL_pending'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(SSLSocket.c.o): in function `SSLSocket_continueWrite':
SSLSocket.c:(.text+0x1e2f): undefined reference to `ERR_clear_error'
/usr/bin/ld: SSLSocket.c:(.text+0x1e3f): undefined reference to `SSL_write'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(Base64.c.o): in function `Base64_encodeDecode.part.0':
Base64.c:(.text+0x1f): undefined reference to `BIO_f_base64'
/usr/bin/ld: Base64.c:(.text+0x27): undefined reference to `BIO_new'
/usr/bin/ld: Base64.c:(.text+0x2f): undefined reference to `BIO_s_mem'
/usr/bin/ld: Base64.c:(.text+0x37): undefined reference to `BIO_new'
/usr/bin/ld: Base64.c:(.text+0x45): undefined reference to `BIO_push'
/usr/bin/ld: Base64.c:(.text+0x55): undefined reference to `BIO_set_flags'
/usr/bin/ld: Base64.c:(.text+0x78): undefined reference to `BIO_write'
/usr/bin/ld: Base64.c:(.text+0x8e): undefined reference to `BIO_ctrl'
/usr/bin/ld: Base64.c:(.text+0x9e): undefined reference to `BIO_free_all'
/usr/bin/ld: Base64.c:(.text+0xc1): undefined reference to `BIO_read'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `WebSocket_buildFrame.constprop.0':
WebSocket.c:(.text+0x441): undefined reference to `RAND_bytes'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `uuid_generate':
WebSocket.c:(.text+0x721): undefined reference to `RAND_bytes'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `WebSocket_connect':
WebSocket.c:(.text+0x929): undefined reference to `RAND_bytes'
/usr/bin/ld: /home/uli/.conan/data/paho-mqtt-c/1.3.9/_/_/package/6fbd1993993594bd3f9451023a96c5ec2eef0e19/lib/libpaho-mqtt3as.a(WebSocket.c.o): in function `WebSocket_upgrade':
WebSocket.c:(.text+0x1dd9): undefined reference to `SHA1_Init'
/usr/bin/ld: WebSocket.c:(.text+0x1def): undefined reference to `SHA1_Update'
/usr/bin/ld: WebSocket.c:(.text+0x1dff): undefined reference to `SHA1_Final'
collect2: error: ld returned 1 exit status


In addition to linking the Paho MQTT libraries, you also need to link OpenSSL, i.e. the ssl and crypto libraries. You can link them, for example using

target_link_libraries(myexecutable ssl crypto)

in CMake or by adding these linker flags for GCC:

-lssl -lcrypto


Posted by Uli Köhler in C/C++

How to initialize new C++ executable project using conan

In the directory where you want to create the project, run (obviously, replace mypackageby the name of everywhere in our code!)

conan new mypackage/1.0.0 -s

-s is important here. It tells conan that the source is available in the project directory and it should not be pulled using git etc.

This will initialize a shared library project, which we will now modify to build an executable.

First, open src/CMakeLists.txt and change add_library() to add_executable(), for example

add_library(mypackage mypackage.cpp)


add_executable(mypackage mypackage.cpp)

Now we shall modify conanfile.py to properly build & install the executable:

    def package(self):
        self.copy("*.h", dst="include", src="src")
        self.copy("*.lib", dst="lib", keep_path=False)
        self.copy("*.dll", dst="bin", keep_path=False)
        self.copy("*.dylib*", dst="lib", keep_path=False)
        self.copy("*.so", dst="lib", keep_path=False)
        self.copy("*.a", dst="lib", keep_path=False)
    def package_info(self):
        self.cpp_info.libs = ["NoxecoDB"]


    def package(self):
        self.copy("mypackage", src="bin", dst="bin", keep_path=False)

    def package_info(self):
        self.env_info.PATH = os.path.join(self.package_folder, "bin")

    def deploy(self):
        self.copy("mypackage", dst="bin", src="bin")

and add

import os.path

to the top of the file

Now let’s add a main() function to  src/mypackage.cpp. Replace the file’s content with

#include <iostream>

int main(int argc, char** argv) {
    std::cout << "Hello World!" <<std::endl;

Now it’s time to install the dependencies & build the project using

conan install . && conan build .

The executable will be in


You can run it using


which will print

Hello World!

I also recommend to add this .gitignore:



Posted by Uli Köhler in C/C++, Conan

How to split strings in C++ using boost::algorithm::split() – a minimal example

#include <boost/algorithm/string/split.hpp> // boost::algorithm::split
#include <boost/algorithm/string/classification.hpp> // boost::is_any_of
#include <string>
#include <iostream>
#include <vector>

int main() {
    std::string mystr = "foo-bar-x";
    // Split by "-"
    std::vector<std::string> splitResult;
    boost::algorithm::split(splitResult, mystr, boost::is_any_of("-"));
    // Print results, one line at a time
    // Prints:
    // foo
    // bar
    // x
    for(const std::string& s : splitResult) {
        std::cout << s << std::endl;


Posted by Uli Köhler in Boost, C/C++

How to fix ModuleNotFoundError: No module named ‘conans’


When running conanfile.py or other Python scripts, you see an error message like

Traceback (most recent call last):
  File "/home/myuser/myproject/conanfile.py", line 1, in <module>
    from conans import ConanFile, CMake
ModuleNotFoundError: No module named 'conans'


Install conan using one of the recommended methods such as the recommended install via pip

sudo pip3 install conan
Posted by Uli Köhler in C/C++, Python

How to fix ArduinoJSON: error: ‘DynamicJSONDocument’ was not declared in this scope


While trying to compile your project, you see an error message like

error: 'DynamicJSONDocument' was not declared in this scope


The Json in DynamicJsonDocument must be spelled camel case: Json, not JSON! The correct spelling is DynamicJsonDocument.

If that does not help, ensure

#include <ArduinoJson.h>

is at the top of the file where the error occurs.

Posted by Uli Köhler in C/C++

FreeRTOS task queue minimal example

This is how you create and use a task queue in FreeRTOS:

Global declaration

Declare the structure of a task (I recommend to use a task type enum class in order to keep the flexibility of using multiple task types:

#include <freertos/queue.h>

enum class I2CTaskType : uint8_t {
    MyTaskType = 0

struct I2CTask {
    I2CTaskType type;
    // Parameters
    int16_t value;
static QueueHandle_t i2cTaskQueue;

Initialization code

Call this once, before using it:

// Create task queue
i2cTaskQueue = xQueueCreate(8 /* Number of queue slots */, sizeof(I2CTask));

In the thread processing the queue

if (xQueueReceive(i2cTaskQueue, (void *)&task, portMAX_DELAY /* Wait infinitely for new tasks */) == pdTRUE) {
    if(task.type == I2CTaskType::MyTaskType) {
        // TODO process task
        Serial.printf("My task type: %d\r\n", task.value);

How to add a task to the queue

void AddTask(int16_t val) {
    I2CTask task;
    task.type = I2CTaskType::MyTaskType;
    task.value = val;
    xQueueSend(i2cTaskQueue, (void*)&task, 10 / portTICK_PERIOD_MS /* timeout */);


Posted by Uli Köhler in C/C++, Embedded, FreeRTOS, PlatformIO

How to fix Arduino error: ‘size_t’ has not been declared


In Arduino, you see an error message like

src/main.cpp:7:48: error: 'size_t' has not been declared
void MyFunction(size_t size);


Include stddef.h where size_t is declared:

#include <stddef.h>

Add this line to the top of the file where the error occured.

Posted by Uli Köhler in Arduino, C/C++, Embedded, PlatformIO

How to fix Arduino I2C Wire error: call of overloaded ‘begin(const int&, const int&, int)’ is ambiguous


You are trying to call Wire.begin() for I2C using

Wire.begin(Pin_I2C_SDA, Pin_I2C_SCL, 400000);

but you see an error message like

src/MyI2C.cpp: In function 'void MyInitI2C()':
src/NyI2C.cpp:139:47: error: call of overloaded 'begin(const int&, const int&, int)' is ambiguous
     Wire.begin(Pin_I2C_SDA,Pin_I2C_SCL, 400000);
In file included from include/MyIO.hpp:2:0,
                 from src/MyI2C.cpp:2:
/home/uli/.platformio/packages/framework-arduinoespressif32/libraries/Wire/src/Wire.h:79:10: note: candidate: bool TwoWire::begin(int, int, uint32_t)
     bool begin(int sda=-1, int scl=-1, uint32_t frequency=0); // returns true, if successful init of i2c bus
/home/uli/.platformio/packages/framework-arduinoespressif32/libraries/Wire/src/Wire.h:80:10: note: candidate: bool TwoWire::begin(uint8_t, int, int, uint32_t)
     bool begin(uint8_t slaveAddr, int sda=-1, int scl=-1, uint32_t frequency=0);


This happens with specific versions of the Arduino framework. For me it happened specifically when upgrading to arduino-esp32 version 2.0.1.

You need to explicitly cast the third argument (400000) to uint32_t in order to tell the compiler which of the two functions you want to call:

Wire.begin(Pin_I2C_SDA, Pin_I2C_SCL, 400000);
Posted by Uli Köhler in Arduino, C/C++, Embedded, PlatformIO

Example of how to do std::enable_if<...> with multiple conditions

Simply use && like this:

std::enable_if<CONDITION1::value && CONDITION2::value, T>

Full example:

template<class T, class I>
constexpr typename std::enable_if<std::is_enum<T>::value && std::is_integral<I>::value, I>::type operator|(T lhs, I rhs) 
    return static_cast<typename std::underlying_type<T>::type>(lhs) | rhs;
Posted by Uli Köhler in C/C++

How to add preprocessor build flags in PlatformIO

In order to define a preprocessor build flag in PlatformIO, add it to build_flags in platformio.ini, prefixing it with -D:


or, in order to define it to a specific value, use




Posted by Uli Köhler in C/C++, PlatformIO

How to add FreeRTOS task (“thread”) to any PlatformIO project

Most PlatformIO default configurations already have FreeRTOS enabled – they just don’t use it.

In order to start a new FreeRTOS “thread” (called task in FreeRTOS-speak), first add these includes:

#include <freertos/FreeRTOS.h>
#include <freertos/task.h>

Now add the task function and handle:

TaskHandle_t myTaskHandle;
void MyTask( void * parameter )
       // TODO Task code goes here
    // if you ever exit the loop, this is here to clean up the resources
    vTaskDelete( NULL );

then start the task using this code once, for example in your main function:

// Start MyTask thread
    MyTask, // Task function
    "MyTask", // Name
    10000, // Stack size
    NULL, // Parameter
    1, // Priority


Posted by Uli Köhler in C/C++, Electronics, Embedded, FreeRTOS, PlatformIO