Datasheet
Table Of Contents
- Features
- Description
- Block Diagram
- SFR Mapping
- Pin Configurations
- Oscillators
- Enhanced Features
- Dual Data Pointer Register DPTR
- Expanded RAM (XRAM)
- Reset
- Power Monitor
- Timer 2
- Programmable Counter Array PCA
- Serial I/O Port
- Interrupt System
- Power Management
- Keyboard Interface
- 2-wire Interface (TWI)
- Serial Port Interface (SPI)
- Hardware Watchdog Timer
- ONCE(TM) Mode (ON Chip Emulation)
- Power-off Flag
- EEPROM Data Memory
- Reduced EMI Mode
- Flash Memory
- Electrical Characteristics
- Absolute Maximum Ratings
- DC Parameters
- AC Parameters
- Explanation of the AC Symbols
- External Program Memory Characteristics
- External Program Memory Read Cycle
- External Data Memory Characteristics
- External Data Memory Write Cycle
- External Data Memory Read Cycle
- Serial Port Timing - Shift Register Mode
- Shift Register Timing Waveforms
- External Clock Drive Waveforms
- AC Testing Input/Output Waveforms
- Float Waveforms
- Clock Waveforms
- Ordering Information
- Packaging Information
- Table of Contents
120
AT89C51ID2
4289C–8051–11/05
Table 93. Program Lock bits of the SSB
Note: U: unprogrammed or "one" level.
P: programmed or "zero" level.
X: do not care
WARNING: Security level 2 and 3 should only be programmed after Flash and code
verification.
Flash Memory Status AT89C51ID2 parts are delivered in standard with the ISP rom bootloader.
After ISP or parallel programming, the possible contents of the Flash memory are sum-
marized on the figure below:
Figure 45. Flash memory possible contents
Memory Organization
When the EA pin high, the processor fetches instructions from internal program Flash. .
If the EA
pin is tied low, all program memory fetches are from external memory.
Program Lock Bits
Protection description
Security
level
LB0 LB1
1 U U No program lock features enabled.
2 P U ISP programming of the Flash is disabled.
3 X P Same as 2, also verify through ISP programming interface is disabled.
0000h
Virgin
Default
After ISP
After parallel
programming
After parallel
programming
After parallel
programming
ApplicationApplication
Virgin
After ISP
or
Dedicated
ISP
Dedicated
ISP
application
Virgin
or
application
Virgin
or
application
FFFFh