Beginner's Guide to STM32CubeMX

STM32 CubeMx tutorial

Introduction

Welcome to this STM32 Cube Mx tutorial. You might be wondering what is it all about? Don’t worry you will find the answers here. STM32 Cube Mx is a free software provided by ST Microelectronics who builds the STM32 line of micro controllers. One issue with these devices is that a lot of code needs to be written to initialize the device.

The STM32 Cube Mx is a GUI that makes life much easier. It helps reduce the burden regarding initializing the micro controller. Bear in mind though that it will not write the code regarding the operation you want to make. Lets take an example, suppose I want to use a STM32F100VGT6 and blink an external LED. The STM32 Cube Mx will help me get the micro controller setup and get an output port ready for me. Unfortunately it will not tell the micro controller that I want to blink the led and at what speed I want the LED to blink. I have however given a small glimpse on how to turn switch on an output port at the end of this article.

So how do you get started with this software? Just follow the steps below.

Create an account on ST

First of all you need to go to http://www.st.com. Register for an account with your email address. Without a registered account you cannot dowload any content fom ST. Before going further you need to know that the STM32 Cube comes in two parts:

1) STM32FXXX firmware

2) STM32 Cube Mx application.

Download STM32FXXX firmware

Once registered you need to download a first software which is called the firmware.
The STM32 firmware is what now replaces the standard peripheral library. You must use this firmware as this is the only one that STM32 Cube Mx recognizes. The implementation of the firmware is completely different from the standard peripheral library and code is written differently.

The firmware is also very specific to the STM32 line you are using. If you are using an STM32F103RBT6 for instance, you will need to download the STM32F1XX firmware. Now if you will use several micro controllers, I would advise to download all relevant firmware based on the STM32 models you will be using.

Once downloaded, install the firmware(s) to a folder and note its(their) location. Do not mix all firmware(if you are using several) in a single folder keep them separate.

Downloading and installing STM32CubeMX

Once you have obtained your firmware(s) next you need to download and install STM32 Cube Mx using your ST account.

Launching STM32 Cube

Once the STM32 firmware(s) and the STM32 Cube Mx is installed, launch the software by clicking on the icon below on your start menu. Note that this is the current icon at time of writing and it might change afterwards.

Startup screen and new project

When the STM32 Cube Mx Launches you will get the screen below. You will need to click on New project to begin.

Option1: Selecting your micro controller(ic’s or custom boards)

Next you need to use the type your micro controller model number in the Part Number Search in the top left corner. Enter the full model number, this will make the search more accurate. Once your micro controller is found, select it. Here I am using the STM32F100RB and I will continue with this micro controller till the end of this article.

Option2: Selecting your board(for manufacturer development boards)

In case you are writing code on a specific development board this is the way to go. For example, below I wanted to go for the STM32 Value line board. The advantage of choosing the board is that STM32 Cube Mx knows how the micro controller and the devices on the board are connected together.

IO Configuration

The next step involves defining which ic pins will do what functions. Bear in mind that certain pins are reserved for certain functions. You can make these pins behave as an input/output port or perform their special function only but not both. An example of such a pin is the ADC1 port. You will also notice that some pins are painted yellow, such as VDD, VSS, VSSA below. These are power pins and cannot perform any other function. The pins which are gray have not been configured. To configure a pin click on it to select. The left menu will adjust accordingly. If you want to configure by function, then use the left menu directly.

Configuring for external clock

Lets start configuring one of the most important pins, the external oscillator pins. The reason why I am doing this step is that I want the IC to use an external oscillator. Since this is a functionality, I will go to the left menu and expand RCC. Next I get three options, I will set the following options:

Settings	Value	Reason
High Speed Clock (HSE)	Crystal/Ceramic resonator	This is the type of oscillator which is on my board
Low Speed Clock (LSE)	Disabled	This is normally for 32KHz oscillators which I don’t intend to use
Master Clock Output	Unchecked	This feature outputs the HSE pulses, I don’t require this feature

Once these settings have been defined, the RCC_OSC_IN and the RCC_OSC_OUT will end up becoming green as shown above. The green color is an indication of a configured pin.

Set debugging options

The debug pins need to be set next. These pins are important as they will allow the onboard or and external programmer to write the program that has been written inside the microcontroller. Since this is a built in function the same procedure are for Configuring for external clock has been used below.

Settings	Value	Reason
Debug	Serial wire	I want the microcontroller and the programmer to use serial wire and not JTAG
System Wake-Up	Unchecked	This feature is not required
Timebase source	Systick	This is the default value

Clock configuration tab

Next we need to define the speed at which we want the microcontroller to operate. In order to do so click on the Clock Configuration tab at the top left next to the Pinout tab. Since I want to use the external oscillator on my board I need to select HSE but the one circled in red in the diagram. If you follow its track back to the left, the symbols indicate an external oscillator. Next the PLLMul has been set to X3. The reason behind is that I have an 8MHz external oscillator on my board and my microcontroller can operate at a maximum speed or 24MHz so 3 x 8MHz=24MHz.

Setting IO Pins

To set IO pins, we will go back to the Pinout tab. Next a right click needs to be done on the pin. In my case I want to set port PC8 as an output pin. In that case the GPIO_Output option needs to be selected. The other options displayed are specific to what functions this pin can perform. I have for the purpose of this post chosen to do this in code and the example is provided at the end. None of the less, setting the IO pin as shown will perform similarly.

Configuration tab

The configuration tab is the one next to the Clock Configuration tab. The purpose of this tab is to give a summary of all the functions that have been switched on in the microcontroller. Since the bare minimum has been done this is why most boxes below are empty. Some functions though not activated explicitly will still be displayed such as DMA and NVIC as shown below. The analog box for instead would have filled up if the ADC had been set up.

Power Consumption Calculator Tab

The Power Consumption tab can be checked next. The purpose of this tab is to give a rough estimate, of the power consumption of the microcontroller and the functions that have been activated. This feature is useful when designing battery powered applications. However, note that in real life other components will be connected to the microcontroller. Their power consumption will need to be taken into consideration as well. To use the tab click the + under Step. A new step window will be displayed and the functions that will be switched on in the microcontroller can be ticked on the right. A bottom section named Results will contain a field called Step Consumption that will display the estimated current consumption of the microcontroller.

Once all the required functions have been ticked a graph of power consumption will be displayed as per below. Please note that in our case the graph is flat as we are not doing anything fancy but with certain funtions swithced on power fluctuations could be observed. Again a note of warning here of simulation v/s actual final circuit needs to be taken into consideration.

Project Settings

The project menu contains a Settings option that can be used to configure parameters for the current project.

Once the project settings is chosen, the screen below will be displayed. The sections in this screen are explained below:

Settings	Description
Project Name	Name of the current project
Project Location	Path of the current project
Toolchain Folder location	The folder into which all generated code will be placed
Toolchain/IDE	The target software for which code needs to be generated
MCU Reference	The microcontroller model for which code needs to be generated
Use Default firmware location	Reference is made here more to the path below this option. The path shown is where the STM32FXX firmware is stored. The default path was not used in this example

Generating code

The finals step once everything is complete is to generate the final configuration code. Click on Project and then on Generate code.

A Progress bar will indicate progress of configuration code generation.

Once the configuration code has been completed, a prompt will be displayed proposing the options shown below.

Loading the code into the IDE

If the Open Folder option is chosen the files shown below will be displayed. To load the configuration code in the Ide, which is EWARM in this current example, double click on the Project icon.

The project will load as per below. All the files in the left are those which are required to make our microcontroller ready for the functions that have been chosen. In this current example switching Leds on ports PC8 and PC9.

Checking board schematic

Before the code is written a quick check on the board schematic is required. The leds are connected to port PC8 and PC9 as mentioned previously. The board schematic also indicates that the port needs to be switched high to light up the leds.

Adding Code to Switch on Leds

Below is a short sample code that does three things

1) The highlighted code that says __HAL_RCC_GPIOC_CLK_ENABLE(); is initializing the PORTC clock. If the PORTC clock is not enabled PORTC does not work. This code is present

2) Next comes the section in red below. In a few words these lines of code are setting up PORTC where pins 8 and 9 will be outputs and no internal pull ups will be required.

3) The final section in brown above gives the instruction to set PORTC pin8 to high and same for PORTC pin 9.

Conclusion

I hope that this short article has given to you an idea of how the STM32 cube MX works. Its a bit intimidating at first but once you get used to it you’ll love the software for the time it saves you. I can say by experience that the initialization process has been much more simplified than with the Standard Peripheral Library. Bear in mind though that with the new STM32 Cube library all codes are completely different and you will need to relearn all of these.