DS2252T View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated
Part Name
Description
Manufacturer
DS2252T Datasheet PDF : 14 Pages
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DS2252T
PIN
35, 37
39
2
24
20
DESCRIPTION
XTAL2, XTAL1. Used to connect an external crystal to the internal oscillator. XTAL1 is the
input to an inverting amplifier and XTAL2 is the output.
GND – Logic ground.
VCC – +5V.
PROG – Invokes the Bootstrap loader on a falling edge. This signal should be debounced so
that only one edge is detected. If connected to ground, the microcontroller will enter Boot-
strap loading on power up. This signal is pulled up internally.
SDI – Self Destruct Input. A logic 1 applied to this input causes a hardware unlock. This
involves the destruction of Encryption Keys, Vector RAM, and the momentary removal of
power from VCCO. This pin should be grounded if not used.
INSTRUCTION SET
The DS2252T executes an instruction set that is object
code compatible with the industry standard 8051 micro-
controller. As a result, software development packages
such as assemblers and compilers that have been writ-
ten for the 8051 are compatible with the DS2252T. A
complete description of the instruction set and operation
are provided in the User’s Guide section of the Secure
Microcontroller Data Book.
MEMORY ORGANIZATION
Figure 2 illustrates the memory map accessed by the
DS2252T. The entire 64K of program and 64K of data
are available to the Byte–wide bus. This preserves the
I/O ports for application use. An alternate configuration
allows dynamic Partitioning of a 64K space as shown in
Figure 3. Any data area not mapped into the NVRAM is
reached via the Expanded bus on Ports 0 and 2. Off–
board program memory is not available for security rea-
sons. Selecting PES=1 provides access to the Real–
time Clock as shown in Figure 4. These selections are
made using Special Function Registers. The memory
map and its controls are covered in detail in the User’s
Guide section of the Secure Microcontroller Data Book.
121395 5/14
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