AT89C51RE2 Atmel Corporation, AT89C51RE2 Datasheet - Page 63

• 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

Write commands
FLASH
CONFIGURATION
SECURITY
7663E–8051–10/08
The following table summarizes the memory spaces for which the write command can be
applied.
Table 36. Memory space & Select page
In case of write command to other area, nothing is done.
The bootloader returns a Write protection (‘P’) if the SECURITY do not allow any write operation
from the bootloader.
The program/data Flash memory area can be programmed by the bootloader by data pages of
up to 128bytes.
If the Flash memory security level is at least ‘2’ (FLB2:0 = ‘110’), no write operation can be per-
formed through the bootloader.
Table 37. Flash Write Authorization Summary
The FCB configuration byte can always be written, whatever are the security levels.
The Security byte can always be written with a value that enables a protection higher than the
previous one.
If attempting to write a lower security, no action is performed and the bootloader returns a pro-
tection error code (‘P’)
Table 38. Security Write Authorization Summary
FLASH
SECURITY
CONFIGURATION
Write
111
110
101
011
Memory/Information Family
Command
write from
FLB2:0
Allowed
Allowed
Forbidden
Forbidden
Forbidden
111
111
Forbidden
Allowed
Allowed
Forbidden
Forbidden
110
110
Security level (HSB)
Security level (HSB)
only a higher level can be write
to FLB2:0
need security level check
Comments/Restriction
FLB2:0
Forbidden
Allowed
Allowed
Allowed
Forbidden
AT89C51RE2
101
101
Forbidden
Allowed
Allowed
Allowed
Allowed
011
011
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