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Letter to the editor: 8-bit horsepower

Chuck Mauro
6/26/2009 04:00 AM EDT

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YibbidyYob
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re: Letter to the editor: 8-bit horsepower
YibbidyYob   7/30/2009 10:24:28 AM
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Great letter Chuck. Some manufacturers are making it really easy to pick the best of both worlds for the application at hand. We've recently switched from an ARM based micro to the Freescale Flexis where you pick the core - 8 or 32 bits. The peripheral set and footprints are identical for the HC08 or the Coldfire V1 cores! Do you want horsepower or low current consumption? Check the right box on the compiler and away you go. Want to change cores, check the other box and recompile, it's that easy. For some applications we found that using the 32 bit ARM and throttling the clock back to reduce power consumption increased the latency for critical routines. These routines are much better handled by an 8 bit processor at a higher clock, and at a lower current consumption. I agree, 8 bitters will be around for a long time.

YevgeniT
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re: Letter to the editor: 8-bit horsepower
YevgeniT   7/30/2009 7:15:56 AM
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I guess, that those (traditional) embedded applications, which have intensive I/O with physical sensors and actuators, together with relative simple control algorithms and entry-level networking - are perfectly implemented with 8-bit microcontrollers. Such kind of applications don't need many on-chip resources, except variable peripheral controllers. But, those applications, which demand DSP ,large memory, sophisticated networking - are more convenient to implement with 32-bit microcontroller. It is well known, that the major part of a silicon real estate is occupied by the memory. For my understanding, cost of manufacturing of 32-bit microcontroller vs 8-bit microcontroller is almost equal - for the same set of peripherals, memory size, package, etc. The really big difference between 8-bit and 32-bit architectures is the software development tools. For 32-bit architectures, the tools are much more powerful, flexible, and convenient, than for 8-bit architectures. It greatly influences cost of the software development. I mean those applications, which could be implemented with any core architecture.

mkellett
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re: Letter to the editor: 8-bit horsepower
mkellett   7/30/2009 7:03:25 AM
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For a great many of the jobs that I take on an 8 bit micro might well be capable but I still use a 32 bit part - why - because my customers get better value if I use a more expensive part but deliver the solution quicker, with lower development costs. In low to medium volumes the cost of the processor core is a very minor part of the total project cost. Annother factor which is pushing the balance in favour of 32 bitters is the increasing demand for ethernet and TCP/IP support in even quite small systems. While you can just about squeeze this into an 8 bit processor your choice of 32 bit (mainly ARM based) parts with on chip ehternet support is greater and the performance is MUCH better. When you compare an 8 bit and a 32 bit device with 64k of RAM, 256k of flash, CAN, USB and ethernet all on chip you find that the price difference is rather small because the peripherals cost much more than the core. This pushes up the volume at which the total cost of ownership crosses over.

csmaurojr
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re: Letter to the editor: 8-bit horsepower
csmaurojr   7/1/2009 2:50:49 PM
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Hi Ray, Thanks for your kind words and great feedback. I agree with you: the smart engineer knows how to pick the right tool for the right job, and uses a bit-width scaled to the job's requirements. It's been my experience that 8 bits is more than enough for the lion's share of embedded applications I've worked on, from computer mice to industrial control to platform stress testing. Chuck Mauro

Ray Keefe
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re: Letter to the editor: 8-bit horsepower
Ray Keefe   7/1/2009 6:20:12 AM
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Hi Chuck, you make a lot of excellent points. We still do extensive work with 8 bit microcontrollers and love the Atmel AVR range. We see a solid forward market for 8 bit because of the ease of use, power management and cost benefits. We also work with 16 bit and 32 bit microcontrollers and these also have their place. It is about picking the best tool for the job. Ray Keefe http://www.successful.com.au

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