signedness using tilde

Hi

I'm a beginner and as a beginner, I start with simple code....

#include "stm32f4xx.h" // Device header
void delayMs(int delay);

int main(void)
	{
		RCC->AHB1ENR |=1;									//ENABLE GPIOA clock
		GPIOA->MODER |= 0x00000400;						// ob 0000 0000 0000 0000 0000 0100 0000 0000
		
		while(1)
			{
				GPIOA->ODR = 0x00000020;
				delayMs(500);
				GPIOA->ODR &=~0x20;
				delayMs(500);
				
			}
		}
	
void delayMs(int delay)
	{
		int i=0;
		
		for(;delay>0;){
				delay --;
				for (i=0;3195;i++);
			}
	}

Kiel does not like tilde at the line GPIOA->ODR &=~0x20;

with the warning: main.c(15): warning: implicit conversion changes signedness: 'int' to 'unsigned int' [-Wsign-conversion].

Without that line, I could switch on the LED connected, but once I add this line, the LED is always on.

Any idea?

Thanks in advance

Fausto Tromba

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