AT89C51RE2 Atmel Corporation, AT89C51RE2 Datasheet - Page 52

• Manufacturer Part Number: AT89C51RE2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RE2

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Spi: 1
• Uart: 2
• Sram (kbytes): 8.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART/OCD
• Watchdog: Yes

Flash Protection from Parallel Programming
52
AT89C51RE2
The three lock bits in Hardware Security Byte (see "In-System Programming" section) are pro-
grammed according to Table 32 provide different level of protection for the on-chip flash memory
FM0.
They are set by default to level 4
Table 32. Program Lock Bit FLB2-0
Program Lock bits
U: unprogrammed
P: programmed
WARNING: Security level 2 and 3 should only be programmed after verification.
Security
level
1
2
3
4
Program Lock Bits
FLB0
U
U
U
P
FLB1
U
U
P
U
FLB2
U
U
U
P
Protection Description
No program lock features enabled.
MOVC instruction executed from external program memory are disabled from
fetching code bytes from internal memory, EA is sampled and latched on reset,
and further parallel programming of the Flash is disabled.
ISP allows only flash verification (no write operations are allowed) but IAP from
internal code still allowed.
Same as 2, also verify through parallel programming interface is disabled and
ISP read operation not allowed.
Same as 3, also external execution is disabled (external bank not accessible)
7663E–8051–10/08