The use of microcontrollers in all kinds of systems is growing by leaps and bounds, says Sanghi--especially as replacements for mechanical control.
Design News: Microcontrollers are used in "embedded" control. What does that term mean?
Sanghi: The literal meaning of "embedded" is "hidden." It's a hidden control. Most end users are usually not aware that there's a microcontroller at work. A microprocessor is essentially a high-performance CPU engine used to manage and control data. A microcontroller, on the other hand, manages events such as turning switches on and off, controlling functions, or reacting to changes in a system.
Q: What are the advantages of replacing an electromechanical system with a microcontroller?
A: There are significant advantages. The first is reliability. Mechanical components on the average have an order of magnitude less reliability than electronics. The chips we make will work for 20 to 50 years. You can also dramatically increase system performance and ease of control, and create competitive differentiation by adding features with the help of a microcontroller. For example, a purely mechanical system would be a coffee maker. But you can add a microcontroller to it, and now you can make the coffee maker keep the coffee at a given temperature, have it turn on right before you wake up, and have it shut off after a certain time.
Q: What types of features do microcontrollers enable?
A: Microcontrollers extend a product's feature set and add the ability to have more pushbutton controls. An average automobile today has about 25 microcontrollers. A high-end car has in excess of 50. They're all adding to a driver's comfort, safety, or convenience. You can have a simple mechanical carburetor control, but the electronic control is more efficient, better for fuel ignition, better for the environment. You could have a totally mechanical thermostat that you have to adjust when the car is too hot or too cold. But many cars today have electronic microcontroller-based thermostat controls. In my car you can set the temperature to, say 72 degrees. I don't have to adjust fan speed or turn off the heater to turn on the air conditioning--it happens automatically.
Q: Any drawbacks or reasons not to use a microcontroller in such an application?
A: If the electromechanical application is too simple in scope, then there would be little benefit in using a microcontroller. Take a seat belt or turning on your automobile headlights--that's the same routine application that has to be executed in a simple manner all the time. There is no decision to be made. A microcontroller is good when there is a decision to be made based on sensing the environment.
Q: How difficult or easy is it for someone trained as a mechanical engineer to design in an 8-bit microcontroller?
A: A dramatic number of mechanical systems are going to electronic, solid-state embedded control. As a result, mechanical engineers are constantly coming across the issue of how to integrate a microcontroller. The mechanical engineers should look at this trend and prepare to stay competitive in the industry by acquiring some electrical engineering skills or hiring some electrical engineers or building relationships with electrical engineering consultants. When migrating a design from an electromechanical to a microcontroller solution, using an electrical engineer is wise to do the job right.
Q: What are the advantages of field-programmable microcontrollers?
A: Microchip pioneered cost-effective field programmability. After you write the code for a product, you can simply buy field-programmable microcontrollers and program the code in a part within a matter of minutes and start to use it. For traditional microcontrollers, you have to wait 10 to 12 weeks to order mask ROM-based parts. That slows down the development process and makes it frustrating for an engineer who's not used to writing code because if he makes an error, there's a very costly cycle to fix that error.
Q: What do design engineers need to know about microcontrollers?
A: Microcontrollers are really quite easy to learn as long as the engineer understands the basic concept of programming. Engineers also need to learn about the various microcontroller peripherals and how to apply them to the application. Most microcontrollers are differentiated by the peripheral set. You could take one microcontroller architecture and do 20 to 30 devices by altering the peripheral set.