at89c5131 ATMEL Corporation, at89c5131 Datasheet - Page 40

• Manufacturer Part Number: at89c5131
• Description: 8-bit Flash Microcontroller With Full Speed Usb Device At89c5131
• Manufacturer: ATMEL Corporation

Flash Memory Status
Figure 19. Flash Memory Possible Contents
Memory Organization
4136C–USB–04/05
0000h
7FFFh AT89C5131A
3FFFh AT89C5130A
Default
Virgin
After ISP
Application
The two lock bits provide different levels of protection for the on-chip code and data,
when programmed as shown to Table 41.
Table 41. Program Lock Bits of the SSB
Notes:
AT89C5131 parts are delivered with the ISP boot in the Flash memory. After ISP or par-
allel programming, the possible contents of the Flash memory are summarized in Figure
19:
In the AT89C5131, the lowest 16K or 32K of the 64 Kbyte program memory address
space is filled by internal Flash.
When the EA is pin high, the processor fetches instructions from internal program Flash.
Bus expansion for accessing program memory from 16K or 32K upward is automatic
since external instruction fetches occur automatically when the program counter
exceeds 3FFFh (16K) or 7FFFh (32K). If the EA pin is tied low, all program memory
fetches are from external memory. If all storage is on chip, then byte location 3FFFh
(16K) or 7FFFh (32K) should be left vacant to prevent and undesired pre-fetch from
external program memory address 4000h (16K) or 8000h (32K).
Security
Level
Program Lock Bits
1
2
3
1. U: unprogrammed or "one" level.
2. P: programmed or “zero” level.
3. X: don’t care
4. WARNING: Security level 2 and 3 should only be programmed after Flash and code
verification.
LB0
U
P
X
Dedicated
ISP
After ISP
Application
Virgin
LB1
U
U
P
or
Protection Description
No program lock features enabled.
ISP programming of the Flash is disabled.
Same as 2, also verify through ISP programming interface is disabled.
After parallel
programming
Application
After parallel
programming
Application
Dedicated
ISP
Virgin
or
After parallel
programming
Application
AT89C5131
Virgin
or
39