AT89LP51ED2-20MU Atmel, AT89LP51ED2-20MU Datasheet - Page 189

• Manufacturer Part Number: AT89LP51ED2-20MU
• Description: 8-bit Microcontrollers - MCU 64KB 20MHz 2.4V-5.5V
• Manufacturer: Atmel

Specifications of AT89LP51ED2-20MU

• Rohs: yes
• Core: 8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 20 MHz
• Program Memory Size: 64 KB
• Data Ram Size: 256 B
• On-chip Adc: Yes
• Operating Supply Voltage: 2.4 V to 5.5 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: VQFN-44
• Mounting Style: SMD/SMT
• Data Rom Size: 4 KB
• Interface Type: 2-Wire, SPI, UART
• Number Of Programmable I/os: 36
• Number Of Timers: 3
• Processor Series: AT89x
• Program Memory Type: Flash
• Factory Pack Quantity: 360

24.1.1
3714A–MICRO–7/11
User Signature Array
The AT89LP51RD2/ED2/ID2 includes a 512-byte User Signature Array in four 128-byte pages.
The User Signature Array is available for serial numbers, firmware revision information, date
codes or other user parameters. The User Signature Array may only be written by an external
ISP programmer when the User Signature Programming Fuse is enabled. When the fuse is
enabled, Chip Erase will also erase the third page of the array. When the fuse is disabled, none
of the pages are affected by page erase/write commands and only pages one and two will be
erased by Chip Erase.
Array is also disabled by the Lock Bits. However, reading the signature is always allowed and
the array should not be used to store security sensitive information. The User Signature Array
may be modified during execution through the In-Application Programming interface, regardless
of the state of the User Signature Programming fuse or Lock Bits.
Some locations of the User Signature Array have special meaning for the system as shown in
Table
loader” on page
byte is read at power-up to set the frequency of the oscillator. Other bytes in these pages may
be used as additional signature space; however, care should be taken to preserve the parame-
ter values when modifying other bytes in the same page.
Table 24-2.
Note:
Table 24-3.
Notes:
Name
BSB
SBV
SSB
OSCCAL
Page #
24-2. Pages one and two store bytes necessary for bootloader operation (See
0
1
2
3
1. The Oscillator Calibration Byte controls the frequency of the internal RC oscillator. The fre-
1. During ISP, a page erase/write of the user signature is only allowed when the User SIgnature
2. Chip Erase will erase this page only if the User SIgnature Programming Fuse is active.
quency is inversely proportional to the calibration value such that higher values result in lower
frequencies. A copy of the factory-set calibration value is stored at location 0008H of the Atmel
Signature.
Programming Fuse is active.
User Signature Parameter Bytes
User Signature ISP Programming Behavior
200). Page three stores a calibration byte for the internal RC Oscillator. This
Definition
Boot Status Byte
Software Boot Vector
Software Security Byte
Oscillator Calibration
0080–00HFH
0000–007FH
0100–017FH
0180–01FFH
Address
Table 24-3
AT89LP51RD2/ED2/ID2 Preliminary
summarizes this behavior. Programming of the Signature
Chip Erase
By Fuse
YES
YES
NO
(2)
Page Erase
By Fuse
By Fuse
By Fuse
By Fuse
Location
0000H
0001H
0080H
0180H
(1)
(1)
(1)
(1)
Default Value
FCH (or FFH)
Page Write
By Fuse
By Fuse
By Fuse
By Fuse
FFH
FFH
(1)
(1)
(1)
(1)
(1)
“Boot-
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