Posted on January 18, 2013 at 04:07I automatically feel stupid asking this question, I feel as if I should know this already. I'm not sure the relation volatile, static and other keywords have with variables that you may access all over the place.
So if I have a variable that I want to be able to read in one function and in another at what point would I want it to be volatile ?
This is what I'm doing I have a var that is a simple char rx from the usart, then in my main i read that char and call the function. I debug and see that the char is in fact 'g' in the interrupt but when i get back around to my main its always 0x00
-- defined in some .h file global to everything
volatile static u8 debugChar; // debug char
-- my int handler, works great !
void USARTx_IRQHANDLER(void)
{
if(USART_GetITStatus(Debug_USART, USART_IT_RXNE) != RESET)
{
debugChar = USART_ReceiveData(Debug_USART);
printf(''\n\rDebug input command: %c\n\r'',debugChar);
USART_ClearITPendingBit(USART2,USART_IT_RXNE);
}
}
-- get back to main after leaving int handler and debugChar is 0
switch(debugChar)
{
case 'g':
testGPIO();
break;
}
I have tried just static, i added volatile to it in an attempt to get it to work thinking volatile was a keyword for ''things that need to change quickly'' but i'm pretty sure thats wrong.
Thanks for reading this far
#declaration-vs-definition
