Microcontroller: A mostly self-contained microprocessor with the focus on I/O processing rather than advanced mathmatics.

PIC: A brandname for MicroChip microcontrollers. The name, I belived was coined when General Instruments had the line. PICs are often referrred as the basic end of microcontrollers due to their small size, inexpense pricing, and small capability.

I2C: A Protocol. Its referred to in print as I2C though its artually I-squared C as in "IIC". Its a two-wire interface created by Signetics in the 80's now owned by Philips. Its common in serial EEProms and REal Time CLocks (RTC). It has the advantage over another protocol called SPI and other things, in that it uses a software addressing scheme so you can attach several devices to the same two wires and it won't require additional microcontroller input/output pins.

FPGA: Field Programmable Gate Array. My distiction here may be subject to correction. I believe this is similar to the ASIC but rather than having the chip burned in permanently, these devices are often serially loaded upon initialization to configure the universal matrix of circuitry inside for its intended purpose. This makes them less expensive because the manufacturer can turn out generic parts.

ASIC: Devices for giving heart-attackes to engineers and management staffs. These are high density programmable devices that require a lot of complexity, money, expertise, money, and computer power (and stillmore money) to design and program. They are expensive chips but are considered the ultimate solution in chip count reduction. They usually appear on circuit boards as square chips. You'll probably see two on a current 56K modem.

PLD: Programmable Logic Device. Sometimes call PAL for Programmable Array Logic. These are simple devices that have a standardized matrix of simple logic gates and you can program them to do simple logic funtions. This saves space when compared to designing the equivalent circuit in simple 7400 series logic gates of the type small-scale integration (SSI) or medium-scale integration (MSI). These are the simplest programmable device to work with, though it usually takes a little programming and a PROM type burner to program them. They are inexpensive.

THE QUESTION AND THE ANSWER:

The simple answer to your final question, How am I supposed to know which to use? is:

You won't be using an ASIC nor a FPGA *if* you don't already know what they are. Usually there cost involve such funds that the designer must get it approved by upper management.

PLDs are logic-glue usually for systems that require more logic. We are basically a microcontroller (MCU) forum here are are biased to solutions that require either the 8051 MCU for mid-range application or the PIC for low end applications.

To find out which without knowing how to choose, this forum can assist. We have experts in the field that never get enough thanks from their bosses and love to come here to assist thankful associates. :)

Tell us what you want to do... and you'll get some advice you could never afford. :)

aka J