AT89C51RE2 Atmel Corporation, AT89C51RE2 Datasheet - Page 40

• 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

Launching flash
commands (activation
sequence)
40
AT89C51RE2
FPL3:0 bits in FCON register are used to secure the launch of programming. A specific
sequence must be written in these bits to unlock the write protection and to launch the operation.
This sequence is 5xh followed by Axh. Table 26 summarizes the memory spaces to program
according to FMOD2:0 bits.
Table 26.
Note:
Erase FM0
Reserved
Reserved
Latches
Column
Reset
FM0
FM0
FM0
HSB
FCB
XAF
1. The sequence 5xh and Axh must be executed without instructions between them otherwise
2. The sequence 5xh and Axh can be executed with the different FMOD0, FMOD1 values, the
3. When the FMOD2 bit is set (corresponding to the serial number field code) no write operation
4. Only the bits corresponding to the previously “full erase” memory space can be written to one.
FM0
the programming is not executed (see flash status register).
last FMOD1:0 value latches the destination target.
can be performed.
FPL3:0
5
A
5
A
5
A
5
A
5
A
5
A
5
A
5
A
Programming Sequences
FPS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Write to FCON
FMOD2
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
FMOD1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
FMOD0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Operation
No action
Write the column latches in FM0
No action
Write the column latches in FM0
extra row space
No action
Full erase FM0 memory area
No action
Reset the FM0 column latches
No action
Write the hardware Security byte
(HSB) See
No action
Write the Fuse Configuration Byte
(FCB)
No action
(4)
7663E–8051–10/08