AS8268 datasheet(84/136 Pages) AMSCO

84 / 136 page

Data Sheet AS8267 / AS8268

Revision 1.0, 19-Jun-07

Page 84 of 136

FLASH Attack Register

If enabled by the ATK_EN bit in the Flash status register, the attack register logs any unauthorized access to the device and

stores it in the Flash memory. After five attacks the device disables the UART1 interface forever.

MSB

LSB

Bit

Symbol

Function

Not used

th attack

rd attack

nd attack

st attack

Whenever the password is not entered correctly and the attack counter is enabled one bit of the attack register

is set and its copy is updated in the Flash memory.

Data Organisation in the FLASH Memory

Program data are stored beginning at address 0000h.

Program data size must not be bigger than 32768 – 16 (0000h – 7FEFh).

The length of the program is stored at the two topmost bytes.

For the 32k Flash memory this means: Length (takes 2 bytes) is stored at 7FFE to 7FFFh.

The 8byte password is stored at 7FF0h to 7FF7h.

Non-volatile Flash status flags are located at 7FF8h to 7FF9h.

Meter data and system parameters are stored in the remaining memory space. The allocation of memory space is totally

up to the MCU program.

The program data will not be protected against overwriting processes from the MCU program.

In case there is no program stored in the Flash (boot loader detects all 0s or all 1s at the program length address) the

boot loader forces the MCU to loop on address 0 (“SJMP $”, Hex code: 80FEh).

FLASH Timing

Parameter

Typ

Unit

Note

Program time

6.75

fclk = 3.58MHz

Erase time

3.39

fclk = 3.58MHz

AS8268 Datasheet(PDF) 84 Page - ams AG