Writing the program to the FLASH

Embedded Devices NET+OS
1

I am attempting to write a program update to the FLASH from my program. I have it successfully downloaded into a 1MB array, then when I attempt to copy it to FLASH using NAFlashWrite() it says that it worked, but when I reboot I just get the 9-1-1 error.

  1. I am using NAAppOffsetInFlash to determine the start sector (7).
  2. I am using NAFlashGetSectorSizes() to determine how much to write. (10 sectors)
  3. I use NAFlashErase() before writing.
  4. NAFlashWrite() is really slow (5 seconds a sector) - is this an indication of a problem?

Anyone who has done this before have any ideas?

-Erik

2

For those interested, I got it to work. It turns out that the attribute ((packed)) doesn’t work very well.

-Erik

3

Erik (All interested),

Per the ARM - Architecture Reference Manual (pg. A2-26, 2001, Issue E) can be UNPREDICTABLE and should therefore be avoided.

*** From the aforementioned document:

The architecturally defined behavior of a load/store instruction which generates an unaligned access is one of the following:

  • It is UNPREDICTABLE
  • It ignores the low-order address bits that make the access unaligned. This means it effectively uses teh formula (address AND 0xFFFFFFFE) for a halfword access, and uses the formula (address AND 0xFFFFFFFC) for a word access.
  • It ignores the low-order address bits that make the access unaligned for the memory access itself, but then uses those low-order bits to control a rotation of the loaded data. (This behavior applies only to the LDR and SWP instructions).

Which of these three options applies to a load/store instruction depends on which instruction it is, and is documented on the instruction pages.

*** End

Essentially, avoid packing structures like the plague. The common reason for packing that I have come across is when implementing a protocol. In such a case it would be best to leave the structure unpacked and manually create the outgoing buffer in its packed form (the reverse would be necessary for incoming buffers).

Cameron

4

That is exactly what I did. :wink: