Using STM32 with the built-in IDE on Simuli Virtual Lab

First, log in to your Simuli account and navigate to the Simuli Virtual Lab. Here we will create a new emulated instance of the STM32. Click on the Launch button under STM32 to get started.

This will open the configuration menu. First, provide a name for the project. Then, we will add the SHT2X Temperature and Humidity Sensor by selecting it from the list of available components. Finally, review that the name for the project and the selected sensors are correct and click on the Launch button.

Once we have clicked on the Launch button, a new instance of the STM32 will be created. It can take a few minutes, so be patient. Once the new instance is ready, an Open button will be visible. Click on this button to open and start working with our STM32.

A new tab with the development environment opens upon clicking Open. On the left side, we have the code editor window along with the terminal at the bottom. On the right side, we have our STM32 Nucleo board with a terminal for interacting with the board and the SHT2X sensor.

Let's work on our first program called blink. This is the equivalent of a 'Hello World' program for Embedded programming. We will write a program that turns an LED on and off in a loop.

The STM32 instances come with support for Platform IO Core (CLI). We will be using it for working on our projects. To know more about Platform IO Core (CLI) and the different commands go to the Platform IO documentation.

First, we need to initialise a new project using Platform IO. Let's create a new folder called STM32-blink which will hold all our code related to the project. You can right-click anywhere in the File Explorer pane, select New Folder, name the folder and click on OK. Now that our Folder is ready, let's go to the terminal and open the newly created folder. Use the following command:

cd /workspace/STM32-blink/

Now we will initialise a new project using Platform IO. Type the following command in the terminal:

pio project init --board nucleo_f411re --project-option "framework=stm32cube"

The pio project init command is used to initialise the project. Then we need to specify the board which we want to use with the --board flag. Finally, Platform IO supports multiple different frameworks for the STM32 like STM32Cube, Arduino, Mbed and others. For a full list of supported frameworks, go here. For this project, we are using the STM32Cube framework.

Once the project init command has run successfully, we will see some new folders inside the STM32-blink folder. We will store the files related to the project in the src folder.

After running the project init command, if you can't see the new files, you may have to reload the project files by clicking on PROJECT in the File Explorer pane.

Create a new file called main.c inside the src folder. This file will hold the code for the blink program. Click on the main.c file to open it up in our code editor. Now, paste the following code inside the main.c file.

#include "stm32f4xx_hal.h"

#define LED_PIN                                GPIO_PIN_5
#define LED_GPIO_PORT                          GPIOA
#define LED_GPIO_CLK_ENABLE()                  __HAL_RCC_GPIOA_CLK_ENABLE()

int main(void)
  GPIO_InitTypeDef GPIO_InitStruct;
  GPIO_InitStruct.Pin = LED_PIN;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  HAL_GPIO_Init(LED_GPIO_PORT, &GPIO_InitStruct); 

  while (1)

void SysTick_Handler(void)

Save the main.c file. Now we need to compile this code. We will use Platform IO for the same. Go to your terminal and type the following command.

pio run

The first time this command is run, Platform IO will download and install the relevant framework and toolchains required for the STM32. This process will take a few seconds.

Now Platform IO will compile our code and output a firmware.bin file. We need to copy this firmware file from the .pio/build/nucleo_f411re to /workspace. Usually you would need to use the cp command, but we have created a custom command called load-firmware for ease of use. Just write the following command and the firmware.bin file will be copied to the workspace folder.


Once we have copied the firmware.bin file, all we need to do is to reset the STM32 by pressing the red button above the STM32. The new firmware will now be loaded and the LED at GPIO 5 will start blinking.

For working with Arduino based programs right in the online IDE, set the framework as arduino in the pio project init command. The Arduino sketches will go into the src folder and the rest of the workflow is the same. Use pio run for compiling the sketches and load-firmware for moving the firmware file to /workspace.

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