STM32F401RE-Nucleo LED and BUTTON's example - stm32

Question

I am trying to run a simple program on my new Nucleo board,
I made this program in order to turn on and off the green led when I press the user's button (the blue one),
#include "stm32f4xx.h"
#include "stm32f4xx_nucleo.h"
#include "system_stm32f4xx.h"
#include "stm32f4xx_hal_gpio.h"
#include "stm32f4xx_hal_rcc.h"
GPIO_InitTypeDef GPIO_InitStructure;
int main(void) {
HAL_Init();
__GPIOA_CLK_ENABLE();
GPIO_InitStructure.Pin = GPIO_PIN_5;
GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStructure.Pull = GPIO_PULLUP;
GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
HAL_GPIO_Init(GPIOA, &GPIO_InitStructure);
__GPIOC_CLK_ENABLE();
GPIO_InitStructure.Pin = GPIO_PIN_13;
GPIO_InitStructure.Mode = GPIO_MODE_INPUT;
GPIO_InitStructure.Pull = GPIO_PULLDOWN;
GPIO_InitStructure.Speed = GPIO_SPEED_FAST;
HAL_GPIO_Init(GPIOC, &GPIO_InitStructure);
while (1) {
if (HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_13)) {
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_RESET);
} else {
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_SET);
}
}
}
But I am getting wrong result:
when I press the user's button, nothing happen,
when I keep pressing the user's button and I restart (by pressing the black button), I get good result,
It seems like the program checks the state of the blue button only at the first run, I don't know why,
Please help me if you have any ideas of what the problem comes from, or if you have a running program that switch the led on button press.

Answer 1

I had the same issue this is how I solve it:
while (1) {
int stateOfPushButton = HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_13);
if ( stateOfPushButton == 1 ) {
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_RESET);
} else {
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_SET);
}
}

Answer 2

Set your button's GPIO Pull to PULLUP:
#include "stm32f4xx.h"
#include "stm32f4xx_nucleo.h"
#include "system_stm32f4xx.h"
#include "stm32f4xx_hal_gpio.h"
#include "stm32f4xx_hal_rcc.h"
GPIO_InitTypeDef GPIO_InitStructure;
int main(void) {
HAL_Init();
__GPIOA_CLK_ENABLE();
GPIO_InitStructure.Pin = GPIO_PIN_5;
GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStructure.Pull = GPIO_PULLUP;
GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
HAL_GPIO_Init(GPIOA, &GPIO_InitStructure);
__GPIOC_CLK_ENABLE();
GPIO_InitStructure.Pin = GPIO_PIN_13;
GPIO_InitStructure.Mode = GPIO_MODE_INPUT;
GPIO_InitStructure.Pull = GPIO_PULLUP;
GPIO_InitStructure.Speed = GPIO_SPEED_FAST;
HAL_GPIO_Init(GPIOC, &GPIO_InitStructure);
while (1) {
if (HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_13)) {
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_RESET);
} else {
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_SET);
}
}
}

Answer 3

Change the GPIO_PULLDOWN mode to GPIO_FLOATING (or something similar)!

Answer 4

This bit of code is what you want to use if your buttons are of the higher current variety like my mechanical 2 state switches:
GPIO_InitStructure.Pull = GPIO_PULLUP;
and adding an int variable also wouldn't hurt, just make sure to do the initialization of your variables only once before starting the main while function, otherwise you end up with leaky memory.
also i see you are not familiar with functions, try the following:
int main(void) {
/* Configure the system clock */
SystemClock_Config();
/* Initialize all configured peripherals */
MX_GPIO_Init();
HAL_Init();
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* start your stuff*/
/* doping stuff*/
/* end your stuff*/
}
}
/* System Clock Configuration*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct;
RCC_ClkInitTypeDef RCC_ClkInitStruct;
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 8;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 4;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
{
Error_Handler();
}
HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
/* SysTick_IRQn interrupt configuration */
HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
}
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
/*Configure GPIO pins : P_BUT_Pin R_BUT_Pin O_BUT_Pin I_CSW_Pin */
GPIO_InitStruct.Pin = P_BUT_Pin|R_BUT_Pin|O_BUT_Pin|I_CSW_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_PULLUP;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
/*Configure GPIO pins : P_LED_Pin R_LED_Pin O_LED_Pin C_LED_Pin */
GPIO_InitStruct.Pin = P_LED_Pin|R_LED_Pin|O_LED_Pin|C_LED_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_PULLUP;
GPIO_InitStruct.Speed = GPIO_SPEED_FAST;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOD, P_LED_Pin|R_LED_Pin|O_LED_Pin|C_LED_Pin,
GPIO_PIN_RESET);
}
or if you are not confident, consider using a tool such as this:[http://www.st.com/en/development-tools/stm32cubemx.html]

Answer 5

Whenever you download code to your board the micro stays in a RESET mode which is why your code appears to not work. Once you press the BLACK RESET button it will run your code from main() and everything will work fine.
Just remember to RESET every time you flash new code on your micro.

Answer 6

If you using Keil MDK, go to your Target options -> Debug -> Select the debugger you are using and click Settings -> In download functions check 'Reset and Run', so the code resets and runs every time you flash it on your Nucleo board.
Your code and GPIO setup works on CubeMX IDE with my Nucleo-F401RE, you just have to enable 'Reset and Run' in Keil if that's the IDE you are using.