Get started with STM32Cube HAL and Nucleo-F401RE: debugging and unit testing

The goal of this tutorial is to demonstrate how simple it is to use PlatformIO IDE for Atom to develop, run and debug a basic blink project with STM32Cube framework for STM32 Nucleo-F401RE board.

  • Level: Intermediate
  • Platforms: Windows, Mac OS X, Linux
Requirements:

Setting Up the Project

There are two ways how to create a new project in PlatformIO IDE: using “New Project” button menu on Home Page or using Menu: PlatformIO > Initialize or Update PlatformIO Project:

../../_images/stm32cube-debugging-unit-testing-1.png

On the next step we choose the desired board (in our case it’s ST Nucleo-F401RE) and also select a directory for our project:

../../_images/stm32cube-debugging-unit-testing-2.png

After processing the selected options (PlatformIO IDE will download and install all required packages, thus the first installation may take some amount of time), we should now have the new project created with the following folder structure:

../../_images/stm32cube-debugging-unit-testing-3.png

The default framework used with ST Nucleo-F401RE board is mbed, but since we decided to use STM32Cube we need to change the framework parameter in Project Configuration File platformio.ini to the next one:

[env:nucleo_f401re]
platform = ststm32
board = nucleo_f401re
framework = stm32cube

After these steps, we have a fully configured project that is ready for developing code with STM32Cube framework.

Adding Code to the Generated Project

Let’s add some actual code to the project. Firstly, we create two main files main.c and main.h in the src_dir folder. Right click on the src in the project window:

../../_images/stm32cube-debugging-unit-testing-4.png

Add next content to main.h:

#ifndef MAIN_H
#define MAIN_H

#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()

#endif // MAIN_H

Add this code to main.c:

#include "main.h"

void LED_Init();

int main(void) {
  HAL_Init();
  LED_Init();

  while (1)
  {
    HAL_GPIO_TogglePin(LED_GPIO_PORT, LED_PIN);
    HAL_Delay(1000);
  }
}

void LED_Init() {
  LED_GPIO_CLK_ENABLE();
  GPIO_InitTypeDef GPIO_InitStruct;
  GPIO_InitStruct.Pin = LED_PIN;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_PULLUP;
  GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
  HAL_GPIO_Init(LED_GPIO_PORT, &GPIO_InitStruct);
}

void SysTick_Handler(void) {
  HAL_IncTick();
}

After this step, we created a basic blink project that is ready for compiling and uploading.

Compiling and Uploading the Firmware

Now we can build the project. To compile firmware we can use three options: Using Build button on PlatformIO Toolbar, using Menu: PlatformIO > Build option from top menu, using targets list in bottom left corner or via hotkeys cmd-alt-b / ctrl-alt-b / f9:

../../_images/stm32cube-debugging-unit-testing-5.png

If everything went well, we should see successful result in the terminal window:

../../_images/stm32cube-debugging-unit-testing-6.png

Now we can upload firmware to the board: Using Build button on PlatformIO Toolbar, using Menu: PlatformIO > Upload from top menu, using targets list in bottom left corner or via hotkeys cmd-alt-u / ctrl-alt-u

../../_images/stm32cube-debugging-unit-testing-7.png

After successful uploading, the green LED2 should start blinking.

Debugging the Firmware

PIO Unified Debugger offers the easiest way to debug your board. Just click Debug button on PlatformIO Toolbar or use Menu: PlatformIO > Debug > Start new debug session:

../../_images/stm32cube-debugging-unit-testing-8.png

We need to wait some time while PlatformIO is initializing debug session and when the first line after the main function is highlighted we are ready to debug:

../../_images/stm32cube-debugging-unit-testing-9.png

We can walk through the code using control buttons, set breakpoints, add variables to Watch window:

../../_images/stm32cube-debugging-unit-testing-10.png

Writing Unit Tests

Now let’s write some tests using PIO Unit Testing feature that can help us test code directly on the target board. PIO Unit Testing engine by default supports only three frameworks: Arduino, Energia and mbed. Since we decided to use STM32Cube we need to implement a custom test_transport to print testing results and specify that condition in Project Configuration File platformio.ini:

[env:nucleo_f401re]
platform = ststm32
board = nucleo_f401re
framework = stm32cube
test_transport = custom
../../_images/stm32cube-debugging-unit-testing-11.png

We will use USART2 on ST Nucleo-F401RE board because it’s directly connected to the STLink debug interface and in OS it can be visible as a Virtual Com Port, so we don’t need any additional USB-UART converter. To implement the custom test_transport we need to create two files unittest_transport.h and unittest_transport.c and put them in the test_dir in the root folder of our project. In these files we need to implement next four functions:

void unittest_uart_begin();
void unittest_uart_putchar(char c);
void unittest_uart_flush();
void unittest_uart_end();

Implementation of unittest_transport.h:

#ifndef UNITEST_TRANSPORT_H
#define UNITEST_TRANSPORT_H

#ifdef __cplusplus
extern "C" {
#endif

void unittest_uart_begin();
void unittest_uart_putchar(char c);
void unittest_uart_flush();
void unittest_uart_end();

#ifdef __cplusplus
}
#endif

#endif // UNITEST_TRANSPORT_H

Implementation of unittest_transport.c:

#include "unittest_transport.h"
#include "stm32f4xx_hal.h"

#define USARTx                           USART2
#define USARTx_CLK_ENABLE()              __HAL_RCC_USART2_CLK_ENABLE()
#define USARTx_CLK_DISABLE()             __HAL_RCC_USART2_CLK_DISABLE()
#define USARTx_RX_GPIO_CLK_ENABLE()      __HAL_RCC_GPIOA_CLK_ENABLE()
#define USARTx_TX_GPIO_CLK_ENABLE()      __HAL_RCC_GPIOA_CLK_ENABLE()
#define USARTx_RX_GPIO_CLK_DISABLE()     __HAL_RCC_GPIOA_CLK_DISABLE()
#define USARTx_TX_GPIO_CLK_DISABLE()     __HAL_RCC_GPIOA_CLK_DISABLE()

#define USARTx_FORCE_RESET()             __HAL_RCC_USART2_FORCE_RESET()
#define USARTx_RELEASE_RESET()           __HAL_RCC_USART2_RELEASE_RESET()

#define USARTx_TX_PIN                    GPIO_PIN_2
#define USARTx_TX_GPIO_PORT              GPIOA
#define USARTx_TX_AF                     GPIO_AF7_USART2
#define USARTx_RX_PIN                    GPIO_PIN_3
#define USARTx_RX_GPIO_PORT              GPIOA
#define USARTx_RX_AF                     GPIO_AF7_USART2

static UART_HandleTypeDef UartHandle;

void unittest_uart_begin()
{
   GPIO_InitTypeDef  GPIO_InitStruct;

  USARTx_TX_GPIO_CLK_ENABLE();
  USARTx_RX_GPIO_CLK_ENABLE();

  USARTx_CLK_ENABLE();

  GPIO_InitStruct.Pin       = USARTx_TX_PIN;
  GPIO_InitStruct.Mode      = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull      = GPIO_PULLUP;
  GPIO_InitStruct.Speed     = GPIO_SPEED_FAST;
  GPIO_InitStruct.Alternate = USARTx_TX_AF;

  HAL_GPIO_Init(USARTx_TX_GPIO_PORT, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = USARTx_RX_PIN;
  GPIO_InitStruct.Alternate = USARTx_RX_AF;

  HAL_GPIO_Init(USARTx_RX_GPIO_PORT, &GPIO_InitStruct);
  UartHandle.Instance          = USARTx;

  UartHandle.Init.BaudRate     = 9600;
  UartHandle.Init.WordLength   = UART_WORDLENGTH_8B;
  UartHandle.Init.StopBits     = UART_STOPBITS_1;
  UartHandle.Init.Parity       = UART_PARITY_NONE;
  UartHandle.Init.HwFlowCtl    = UART_HWCONTROL_NONE;
  UartHandle.Init.Mode         = UART_MODE_TX_RX;
  UartHandle.Init.OverSampling = UART_OVERSAMPLING_16;

  if(HAL_UART_Init(&UartHandle) != HAL_OK) {
    while(1){}
  }

}

void unittest_uart_putchar(char c)
{
    HAL_UART_Transmit(&UartHandle, (uint8_t*)(&c), 1, 1000);
}

void unittest_uart_flush(){}

void unittest_uart_end() {
  USARTx_CLK_DISABLE();
  USARTx_RX_GPIO_CLK_DISABLE();
  USARTx_TX_GPIO_CLK_DISABLE();
}

Now we need to add some test cases. Tests can be added to a single C file that may include multiple tests. First of all, in this file we need to add three default functions: setUp, tearDown and main. setUp and tearDown are used to initialize and finalize test conditions. Implementations of these functions are not required for running tests but if you need to initialize some variables before you run a test, you use the setUp function and if you need to clean up variables you use tearDown function. In our example we will use these functions to accordingly initialize and deinitialize LED. main function acts as a simple program where we describe our test plan.

Let’s implement some basic tests for blinking routine:

#include <main.h>
#include <unity.h>

#ifdef UNIT_TEST

void setUp(void) {
    HAL_Init();

    LED_GPIO_CLK_ENABLE();

    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.Pin = LED_PIN;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_PULLUP;
    GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
    HAL_GPIO_Init(LED_GPIO_PORT, &GPIO_InitStruct);
}

void tearDown(void) {
    HAL_GPIO_DeInit(LED_GPIO_PORT, LED_PIN);
}

void test_led_builtin_pin_number(void) {
    TEST_ASSERT_EQUAL(LED_PIN, GPIO_PIN_5);
}

void test_led_state_high(void) {
    HAL_GPIO_WritePin(LED_GPIO_PORT, LED_PIN, GPIO_PIN_SET);
    TEST_ASSERT_EQUAL(HAL_GPIO_ReadPin(LED_GPIO_PORT, LED_PIN), GPIO_PIN_SET);
}

void test_led_state_low(void) {
    HAL_GPIO_WritePin(LED_GPIO_PORT, LED_PIN, GPIO_PIN_RESET);
    TEST_ASSERT_EQUAL(HAL_GPIO_ReadPin(LED_GPIO_PORT, LED_PIN), GPIO_PIN_RESET);
}

int main() {
    UNITY_BEGIN();
    RUN_TEST(test_led_builtin_pin_number);

    for (unsigned int i = 0; i < 5; i++)
    {
        RUN_TEST(test_led_state_high);
        HAL_Delay(500);
        RUN_TEST(test_led_state_low);
        HAL_Delay(500);
    }

    UNITY_END(); // stop unit testing

    while(1){}
}

#endif

Also, we need to wrap the main function in our application:

#ifndef UNIT_TEST
int main(void)
#else
int app_main(void)
#endif
{
  HAL_Init();
  LED_Init();

  while (1)
  {
    HAL_GPIO_TogglePin(LED_GPIO_PORT, LED_PIN);
    HAL_Delay(1000);
  }
}

Now we are ready to upload tests to the board. To do this we can use Menu: PlatformIO > Test (Unit Testing) from top menu or targets list in bottom left corner:

../../_images/stm32cube-debugging-unit-testing-12.png

After processing we should see a detailed report about testing results:

../../_images/stm32cube-debugging-unit-testing-13.png

Congratulations! As we can see from the report, all our tests went successfully!

Conclusion

Now we have a decent template that we can improve for our next more complex projects.