Posted on March 29, 2012 at 22:54
In this case Address is a 32-bit unsigned value.
vu16 is a volatile unsigned short, it's defined in stm32f10x.h
The casting converts the 32-bit number into a pointer to a 16-bit value, and the leading asterisk writes to that.
ie WORD[0x08001000] = 0x1234
Reviewing the library source
/*******************************************************************************
* Function Name : FLASH_ProgramHalfWord
* Description : Programs a half word at a specified address.
* Input : - Address: specifies the address to be programmed.
* - Data: specifies the data to be programmed.
* Output : None
* Return : FLASH Status: The returned value can be: FLASH_BUSY,
* FLASH_ERROR_PG, FLASH_ERROR_WRP, FLASH_COMPLETE or
* FLASH_TIMEOUT.
*******************************************************************************/
FLASH_Status FLASH_ProgramHalfWord(u32 Address, u16 Data)
{
FLASH_Status status = FLASH_COMPLETE;
/* Check the parameters */
assert_param(IS_FLASH_ADDRESS(Address));
/* Wait for last operation to be completed */
status = FLASH_WaitForLastOperation(ProgramTimeout);
if(status == FLASH_COMPLETE)
{
/* if the previous operation is completed, proceed to program the new data */
FLASH->CR |= CR_PG_Set;
*(vu16*)Address = Data;
/* Wait for last operation to be completed */
status = FLASH_WaitForLastOperation(ProgramTimeout);
if(status != FLASH_BUSY)
{
/* if the program operation is completed, disable the PG Bit */
FLASH->CR &= CR_PG_Reset;
}
}
/* Return the Program Status */
return status;
}
One optimization trick is that you don't need to toggle the PG bit for each half word.
I've never seen FLASH_AR used in writing to flash, only the page erase, but I can see how the documentation may lead you to believe otherwise.
