Xilinx UG129 manual Introduction, PicoBlaze Microcontroller Features

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Chapter 1

Introduction

The PicoBlaze™ microcontroller is a compact, capable, and cost-effective fully embedded 8-bit RISC microcontroller core optimized for the Spartan®-3, Virtex®-II, and Virtex-II Pro FPGA families. The PicoBlaze microcontroller provides cost-efficient microcontroller- based control and simple data processing.

The PicoBlaze microcontroller is optimized for efficiency and low deployment cost. It occupies just 96 FPGA slices, or only 12.5% of an XC3S50 FPGA and a miniscule 0.3% of an XC3S5000 FPGA. In typical implementations, a single FPGA block RAM stores up to 1024 program instructions, which are automatically loaded during FPGA configuration. Even with such resource efficiency, the PicoBlaze microcontroller performs a respectable 44 to 100 million instructions per second (MIPS) depending on the target FPGA family and speed grade.

The PicoBlaze microcontroller core is totally embedded within the target FPGA and requires no external resources. The PicoBlaze microcontroller is extremely flexible. The basic functionality is easily extended and enhanced by connecting additional FPGA logic to the microcontroller’s input and output ports.

The PicoBlaze microcontroller provides abundant, flexible I/O at much lower cost than off-the-shelf controllers. Similarly, the PicoBlaze peripheral set can be customized to meet the specific features, function, and cost requirements of the target application. Because the PicoBlaze microcontroller is delivered as synthesizable VHDL source code, the core is future-proof and can be migrated to future FPGA architectures, effectively eliminating product obsolescence fears. Being integrated within the FPGA, the PicoBlaze microcontroller reduces board space, design cost, and inventory.

The PicoBlaze FPC is supported by a suite of development tools including an assembler, a graphical integrated development environment (IDE), a graphical instruction set simulator, and VHDL source code and simulation models. Similarly, the PicoBlaze microcontroller is also supported in the Xilinx System Generator development environment.

The various PicoBlaze code examples throughout this application note are written for the Xilinx KCPSM3 assembler. The Mediatronix pBlazIDE assembler has a code import function that reads the KCPSM3 syntax.

PicoBlaze Microcontroller Features

As shown in the block diagram in Figure 1-1, the PicoBlaze microcontroller supports the following features:

•16 byte-wide general-purpose data registers

•1K instructions of programmable on-chip program store, automatically loaded during FPGA configuration

PicoBlaze 8-bit Embedded Microcontroller www.xilinx.com 11

UG129 (v1.1.2) June 24, 2008