flash locking sequence for erase & program

babidesai123 · ‎2004-02-16

Posted on February 16, 2004 at 14:35

babidesai123 · ‎2011-05-17

Posted on May 17, 2011 at 11:58

hi,

i wanted to more about flash locking & unlocking sequece during dflashh erase & programming.

Doubts:

1. what i have observed is during flash byte program, we are programming the flash byte FLASH_COMMON_X555 with 0xaa in order to un lock the main flash.

Can we prorgram the same byte after unlocking it?

Say

In code it is defined as:

#define FLASH_COMMON_XAAA (volatile unsigned char xdata *) 0xaAAA

#define FLASH_COMMON_X555 (volatile unsigned char xdata *) 0xa555

So, can we program the location 0xa555.

Purvi

joseph2399 · ‎2011-05-17

Posted on May 17, 2011 at 11:58

Yes, you can write to any location within the flash sector that you have just selected and unlocked. the unlocking sequence of writing AAh to X555h then 55h to XAAAh only writes to the internal state machine, and not to the physical flash memory locations.