STM32 HAL GPIO Read Pin (GPIO Input Example)

In this tutorial, we’ll create an STM32 HAL GPIO Read Pin Example project. You’ll learn all the steps to configure the STM32 GPIO Input Pin Read Example in STM32CubeMX, flash the code from STM32CubeIDE to the blue pill STM32F103C8T6 board, and start testing with a push button & LED. Without further ado, let’s get right into it!

Table of Contents

  1. STM32 HAL GPIO Read Pin Example (hal_gpio_readpin)
  2. STM32 HAL GPIO Read Pin Example (CubeMX Configurations)
  3. STM32 HAL GPIO Read Pin Example Code Explained
  4. STM32 GPIO Input Example Testing
  5. Wrap Up

STM32 HAL GPIO Read Pin Example (hal_gpio_readpin)

Objectives of This STM32 HAL GPIO Read Pin Example Project:

  • Configure GPIO Input & Output Pins Within CubeMX Tool
  • Use HAL_GPIO_ReadPin() To Read The Input Push Button State
  • Use HAL_GPIO_WritePin() To Change The Output Pin State

STM32 HAL GPIO Read Pin Example (CubeMX Configurations)

Step #1

Open STM32CubeMX, create a new project, and select the STM32F103C8T6 target microcontroller. Note that the STM32 BluePill board has two common target microcontrollers (STM32F103C8T6 & STM32F103C6T6). So you need to select the exact target microcontroller on your hardware board.

This example project should work flawlessly on any STM32 target microcontroller, you just need to select the target MCU that matches your hardware board.

Step #2

Go to the RCC clock configuration page and enable the HSE external crystal oscillator input.

Push Button Pin: Click on the PA9 GPIO pin and select it to be in GPIO_Input mode. Note: you can use any other pin you want instead.

LED Pin: Click on the PA8 GPIO pin in the “Pinout View” and select it to be in GPIO_Output mode. Note: you can use any other pin you want instead.

STM32 RCC External Clock Selection CubeMX

Step #3

Go to the clock configurations page, and select the HSE as a clock source, PLL output, and type in 72MHz for the desired output system frequency. Hit the “ Enter” key, and let the application solve for the required PLL dividers/multipliers to achieve the desired clock rate.

The reason behind this: using the external onboard oscillator on the BluePill board provides a more accurate and stable clock, and using a 72MHz as a system clock pushes the microcontroller to its limits, so we get the maximum performance out of it. As long as we don’t care about the application’s power consumption.


Step #4

Finally, go to the Project Manager, give your project a name, select the toolchain/IDE to be STM32CubeIDE, and click on the Generate Code button.

The STM32CubeMX tool will generate the initialization code & the project main files and it’ll prompt you to open the project in STM32CubeIDE. Select, open project, and let’s move to the next step.

STM32 GPIO HAL Pin Read Push Button CubeMX

Then, open the project in the IDE you’re using. And head over to the main.c file. So we can start writing the application code and have a look at the initialization code generated by the STM32 CubeMX tool.

Step #5

Copy the code below into your main.c file replacing the auto-generated code from the beginning of the fill till the main function. You should leave everything else under the main() function in the main.c file as is.

STM32 HAL GPIO Read Pin Example Code (HAL_GPIO_ReadPin)

STM32 HAL GPIO Read Pin Example Code Explained

The CubeMX tool has generated the initialization C-Code for us. There is nothing special about it except the GPIO init function shown down below.

As you can see, the input pin (A9) is set to Hi-Z or High-Impedance mode, it’s called no-pull (no pull-up or down). You can, however, set the pin to pull-up or pull-down depending on your preference.

We’ll head over again to the HAL documentation and search for the GPIO chapter, where we’ll find this listing for the available APIs. The APIs are hyperlinked in the documentation file, so you can click the name of the function to go directly to its detailed description.


So, let’s take a closer look at the HAL_GPIO_ReadPin() function.

HAL GPIO Pin Read Function Description

In this STM32 GPIO Read Input Pin Example, we’ve read the pin state for the push button (A9) and used it to drive the LED pin (A8) High or Low depending on the push button input pin state. It’s a very simple application and you can modify it as you want to meet your application’s needs. Let’s now move to the testing of this example project on a real STM32 blue pill board.

STM32 GPIO Input Example Testing

Step #1

Refer To The Blue Pill Board Schematic & Pinout

Blue pill pinout

Step #2

Connect The ST-Link To The USB Port & SWD Pins On Board

STM32 GPIO HAL Led Blinking

Step #3

Click The Debug Button To Compile The Code & Flash It To The Board & Start A Debugging Session


❕ Note

If the debugger GDB server returns an error to you over and over. Then, don’t try starting the debug session again. Until you move the BOOT0 pin jumper from 0 to logic 1. Then try debugging again, it should work just as fine. But don’t forget to set the BOOT0 pin back to 0 so it starts your application on start-up after restarting the microcontroller.

Step #4

You Can Stop The Debugging Session Or Keep It Going. But You Need To Restart The MCU Once To Run The New Application At The Booting Process.

Required Parts For STM32 Examples

All the example Code/LABs/Projects in this STM32 Series of Tutorials are done using the Dev boards & Electronic Parts Below:

QTY.Component NameAmazon.comAliExpresseBay
1STM32-F103 BluePill Board (ARM Cortex-M3 @ 72MHz)AmazonAliExpresseBay
1Nucleo-L432KC (ARM Cortex-M4 @ 80MHz)AmazonAliExpresseBay
1ST-Link V2 DebuggerAmazonAliExpresseBay
1LEDs KitAmazonAmazonAliExpresseBay
1Resistors KitAmazonAmazonAliExpresseBay
1Capacitors KitAmazonAmazonAliExpress & AliExpresseBay & eBay
1Jumper Wires PackAmazonAmazonAliExpress & AliExpresseBay & eBay
1Push ButtonsAmazonAmazonAliExpresseBay
1Micro USB CableAmazonAliExpresseBay

★ Check The Links Below For The Full Course Kit List & LAB Test Equipment Required For Debugging ★

Download Attachments

You can download all attachment files for this Article/Tutorial (project files, schematics, code, etc..) using the link below. Please consider supporting our work through the various support options listed in the link down below. Every small donation helps to keep this website up and running and ultimately supports the whole community.

Wrap Up

In conclusion, it was quite easy to create an STM32 GPIO input pin read example project to read a push button with the HAL_GPIO_ReadPin() function. You can play with different settings like adding multiple IO pins, and so on.

If you’re just getting started with STM32, you need to check out the STM32 Getting Started Tutorial here.

Follow this STM32 Series of Tutorials to learn more about STM32 Microcontrollers Programming.

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Khaled Magdy
Embedded systems engineer with several years of experience in embedded software and hardware design. I work as an embedded SW engineer in the Automotive & e-Mobility industry. However, I still do Hardware design and SW development for DSP, Control Systems, Robotics, AI/ML, and other fields I'm passionate about.
I love reading, writing, creating projects, and teaching. A reader by day and a writer by night, it's my lifestyle. I believe that the combination of brilliant minds, bold ideas, and a complete disregard for what is possible, can and will change the world! I will be there when it happens, will you?

2 thoughts on “STM32 HAL GPIO Read Pin (GPIO Input Example)”

  1. your tutorials are so nice. i have learned pic microcontrollers and now focusing on stm32.

    it helps alot.

    you should make youtube videos on these tutorials. that will be very helpful

    thank you very much


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