DS5000FP

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DESCRIPTION

The DS5000FP Soft Microprocessor Chip is an 8051-compatible processor based on NV RAM

technology. It is substantially more flexible than a standard 8051, yet provides full compatibility with the

8051 instruction set, timers, serial port, and parallel I/O ports. By using NV RAM instead of ROM, the

user can program and then reprogram the microcontroller while in-system. The application software can

even change its own operation, which allows frequent software upgrades, adaptive programs, customized

systems, etc. In addition, by using NV SRAM, the DS5000FP is ideal for data-logging applications and it

connects easily to a Dallas real-time clock for time stamp and date.

The DS5000FP provides the benefits of NV RAM without using I/O resources. It uses a nonmultiplexed

byte-wide address and data bus for memory access. This bus can perform all memory access and provides

decoded chip enables for SRAM. This leaves the 32 I/O port pins free for application use. The DS5000FP

uses ordinary SRAM and battery backs the memory contents with a user’s external lithium cell. Data is

maintained for over 10 years with a very small lithium cell. A DS5000FP also provides crash-proof

operation in portable systems or systems with unreliable power. These features include the ability to save

the operating state, Power-fail Reset, Power-fail Interrupt, and Watchdog Timer.

A user loads programs into the DS5000FP via its on-chip Serial Bootstrap Loader. This function

supervises the loading of code into NV RAM, validates it, and then becomes transparent to the user.

Software can be stored in an 8-kbyte or 32-kbyte CMOS SRAM. Using its internal Partitioning, the

DS5000FP will divide this common RAM into user programmable code and data segments. This

Partition can be selected at program loading time, but can be modified anytime later. It will decode

memory access to the SRAM, communicate via its byte-wide bus and write-protect the memory portion

designated as ROM. Combining program and data storage in one device saves board space and cost. The

DS5000FP can also access a second 32 kbytes of NV RAM but this area is restricted to data memory. The

DS2250(T) and DS5000(T) are available for a user who wants a pre-constructed module using the

DS5000FP, RAM, lithium cell, and optional real-time clock. Each device is described in separate data

sheets, available on our website at www.maxim-ic.com/microcontrollers. More details are contained in

the Secure Microcontroller User’s Guide.