Xilinx UG129 manual Strengths, Weaknesses

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Chapter 1: Introduction

performance requirements. A completely parallel implementation is faster but consumes more FPGA resources.

A microcontroller embedded within the FPGA provides the best of both worlds. The microcontroller implements non-timing crucial complex control functions while timing- critical or data path functions are best implemented using FPGA logic. For example, a microcontroller cannot respond to events much faster than a few microseconds. The FPGA logic can respond to multiple, simultaneous events in just a few to tens of nanoseconds. Conversely, a microcontroller is cost-effective and simple for performing format or protocol conversions.

Table 1-1:PicoBlaze Microcontroller Embedded within an FPGA Provides the Optimal Balance between

Microcontroller and FPGA Solutions

		PicoBlaze Microcontroller	FPGA Logic
	• Easy to program, excellent for control		• Significantly higher performance
		and state machine applications	• Excellent at parallel operations
Strengths	• Resource requirements remain constant		• Sequential vs. parallel implementation
		with increasing complexity	trade-offs optimize performance or cost
	• Re-uses logic resources, excellent for		• Fast response to multiple, simultaneous
		lower-performance functions	inputs
	•	Executes sequentially	• Control and state machine applications
	• Performance degrades with increasing		more difficult to program
Weaknesses		complexity	• Logic resources grow with increasing
	•	Program memory requirements	complexity
		increase with increasing complexity
	• Slower response to simultaneous inputs

16	www.xilinx.com	PicoBlaze 8-bit Embedded Microcontroller
		UG129 (v1.1.2) June 24, 2008