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NEW! The Motorola Nitron HC08 Q-Family
Just last week, Motorola introduced the new Nitron HC08 Q-Family. These tiny new chips are well suited for extremely small applications such as remote controls and key fobs. Some of the family's key features include:
You can currently order a promotional development kit from Motorola. For $25, you get a small development board, serial cable, and a fully functional version of Metrowerks CodeWarrior Development Studio for HC08, Special Edition. This special version of CodeWarrior let's you program any HC08 (including the Nitron) with a limit of 4 KB of program size. You can order this development kit on the web at http://motorola.dartmail3.net/cgi-bin3/flo?y=hNfP0Ddm1U0EIe042T0Al.
With the Nitron family, Motorola provides alternatives to the Microchip PIC, Atmel AVR, and Philips LPC51 families. (For reference, look at our review of the Philips LPC51 family at http://www.base2software.com/eiarchives/ie200205.htm.) Nitron microcontrollers come in 8- and 16-pin DIP, SOIC, and TSSOP packages depending upon model and start around $0.70 each (Qty 1K). For more information, check out the Motorola website at http://www.motorola.com/mcu.
Base2 Software Design provides embedded software development services for your product development needs. We support all levels of embedded software including:
Whether you need help finishing a project or if you're just forming a product development team, give us a call at 510/745-7773 or send an e-mail to mailto:email@example.com and see how we can help you bring your product to market.
"Real-time" is a term that is often bandied about in the embedded software industry. When applied to other industries, real-time can mean any number of things. But what does it really mean in an embedded system? How does it affect your software? Your hardware?
Let's start by defining "real-time". Real-time can be defined as the ability to perform a task within a given time constraint.
In embedded systems, there are two types of real-time requirements: hard real-time and soft real-time. Not meeting a hard real-time requirement results in a failure. Not meeting a soft real-time requirement does not result in a failure. The definition of a failure is open to interpretation but generally refers to data loss, damage to equipment, or harming a patient.
Hard real-time requirements can be found in medical devices, cars, aircraft, and even consumer electronics. It's pretty easy to see that if a hard real-time requirement is not met in your car's engine controller, the result could be an undrivable car or even engine damage. Of course, many failures are not that dramatic. If an MP3 player doesn't meet it's real-time requirement to service the audio CODEC on a regular basis, the result is choppy or unintelligible audio.
Soft real-time requirements are commonplace and often refer to human interface elements (e.g. button response and display change rates). That's because people respond so much slower than computers. We simply can't tell the difference between a 100 ms response time and a 200 ms response time.
In most real-time systems, there is a mix of hard and soft real-time requirements. It is very important to identify these requirements early in the design process so that the proper hardware and software are created to meet those requirements. A good way to avoid confusion with hard and soft real-time requirements is by using careful wording. By using words like "must" and "shall", a hard real-time requirement is indicated. Words like "may" and "should be" indicate a soft real-time requirement. Here are just a few examples:
It is important to note that meeting real-time requirements is ultimately tied to a hardware mechanism whether it be interrupts, a timer, or even a super-fast CPU. This is true even with real-time operating systems (RTOSs). For the hardware and firmware designers, the challenge lies in the best way to meet real-time requirements. A good way to look at these requirements is by time ranges:
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