Re: Accessing 20-bit memory range - issues with indirect addressing mode

2014-05-04 22:04 GMT+02:00 Tomek Lorek <[email protected]>:
> 1. Possibly the main reason my code did not work was using
> __asm__ __volatile__ ("movx #0, @%0"::"r"(flash));
> instead of
> __asm__ __volatile__ ("movx.b %1, @%0":"=r"(flash):"m"(Byte));
>
> But I don't understand why the latter works and the first doesn't (the
> 1st one causes "tilib: MSP430_State: Internal error (error = 68)" in
> mspdebug right after stopping the program execution.

Just checked the flashdump diff right before and after executing the
program - "movx #0, @%0"::"r"(flash))" variant messed up the flash
bank A from where I was running the code and it erased 0xc400 instead
of 0x1c400.
Do you have any idea why?

The code is:
unsigned long flash_addr = 0x1c400;
unsigned int flash;
unsigned int sr;

FCTL3 = FWKEY; // Clear Lock bit
while (FCTL3 & BUSY) ;
FCTL1 = FWKEY + MERAS; // Set MERAS bit

__asm__ __volatile__ ("mov r2,%0":"=r"(sr):);
_DINT();
__asm__ __volatile__ ("movx.a %1,%0":"=r"(flash):"m"(flash_addr));
__asm__ __volatile__ ("movx #0, @%0"::"r"(flash));               // <-
the line that is under discussion

__asm__ __volatile__ ("mov r2,%0":"=r"(sr):); // save SR before disabling IRQ
__dint();

while (FCTL3 & BUSY) ; // test busy
FCTL1 = FWKEY; // Clear MERAS bit
FCTL3 = FWKEY + LOCK; // Set LOCK bit

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