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Richard Erlacher
06/22/10 22:50
Read: 837 times
Denver, Co
USA


 
#176843 - not a point of disagreement, but you missed it anyway
Responding to: Per Westermark's previous message
Per Westermark said:
richard said:
The real question is not whether or not a thing is possible, but, whether it has been done.

If you want to ask such a question, you better be more specific about exactly what has been done.

Your previous post was about isolating 8 bits at a time, and I did mention 32-bit chips that did 8-bit reads without need for any separate isolation.

Having two indices is good for a 8051. Most 32-bit processors may have 8 or maybe even 32. Sometimes with support for auto-increment or auto-decrement.

You can get an ARM chip for $1, even if most people probably ends up with $3-$10 chips depending on needs.

While it's interesting to note, the previous two comments muddy the water rather than clearing it. Are you saying that a $1 ARM supports auto-inc/dec?

Some of the ARM can handle 8-bit accesses from memory without extra costs. Some can't. The ARM core produces the required info - it's a question of the memory controller glued to the ARM core.

If the ARM core does it in two clocks or five clocks is fun, but at the same time some ARM may do 40MHz and some may do 400MHz. So the length of a clock can vary quite a lot.

A LPC17xx does:
unsigned char *p1,*p2;

*p1++ = *p2++ // 4 clock cycles = 1MB/s at 4MHz or 25MB/s at 100MHz. Some parts do 30MB/s at 120MHz.

The LPC17xx are a bit high-end, resulting in most models costing around $4-$5 in volume.
But you can find much cheaper Cortex-M3 chips too.

If running 100MHz, you get a cycle time of 10ns or 40ns/transfer.
If running 120MHz, you get 33ns/transfer.

Having a PLL means that the same chip can dynamically switch speed, depending on needs.

The cheapest NXP Cortex-M3 seems to be around $1.5 to $2 and manages up to 72MHz.

Richard said:
What do you have in mind as far as your notion that all instructions/operations can be implemented? Is there a core that you'd choose for DIY MCU applications?

No magic hidden in the sentence. Every instruction you can implement in an 8-bit processor can be implemented in a 16-bit or 32-bit processor. So it all comes back to my previous claim. You can't say that 8-bitters are faster for microcontroller work. You can only say that a specific 8-bit processor can win over a specific 32-bit processor when doing a specific task. There is nothing magic in an 8-bit processor that can't exist in a 16-bit or even 84-bit processor.

I don't disagree with anything you've said, Per, but just because it's possible to implement an instruction doesn't mean that it's been done for me. If I want a product, rather than a concept, knowing it's possible doesn't help me.

If you're after a product, knowing its implementation cost is pretty important. In the past, I've always found the ARM's considerably more costly to put on a board. That doesn't mean it's unreasonable to consider ARM, or any other 16/32-bit MCU, but one does have to consider its implementation cost. BTW, are any of those $1 ARM's priced that low in handfuls?

RE



List of 104 messages in thread
TopicAuthorDate
So What Is An 8051/2 Good For?      Andy Neil      06/17/10 16:35      
   thoughts      Erik Malund      06/18/10 04:36      
      The Future of the 805x      Joseph Hebert      06/18/10 08:40      
         PARC      Rob Klein      06/18/10 09:01      
            Bigger Hammers      Joseph Hebert      06/18/10 09:37      
               re: Bigger Hammers      Rob Klein      06/18/10 10:59      
               The opposite problem seems more common here!      Andy Neil      06/18/10 15:50      
         Would Toyota have had the problem if ...      Erik Malund      06/18/10 09:31      
            Toyota: Case in point      Joseph Hebert      06/18/10 09:46      
            RE: Toyota      Andy Neil      06/18/10 10:17      
               It was a mechanical fix ...      Richard Erlacher      06/18/10 22:37      
            Parallel Processing      Justin Fontes      06/18/10 10:35      
               Sometimes the practical reality is of little consequence      Richard Erlacher      06/18/10 22:45      
                  Totally Agree, but I was looking for a magic bullet      Justin Fontes      06/18/10 23:09      
                  RE: "outperform"      Andy Neil      06/19/10 01:10      
                     There are some operations ...      Richard Erlacher      06/19/10 06:19      
                        rephrased      Erik Malund      06/19/10 06:44      
                        Now, you are extrapolating      Per Westermark      06/19/10 06:44      
                           good points, but      Erik Malund      06/19/10 07:12      
                              How many 8051 chips uses 0.13u?      Per Westermark      06/19/10 08:57      
                                 not yet      Erik Malund      06/19/10 13:05      
                           not exactly ...      Richard Erlacher      06/20/10 09:39      
                              Do not get focused on one operation...      Michael Karas      06/20/10 10:20      
                              any 8-bit instruction can exist in a 32-bit processor      Per Westermark      06/20/10 12:14      
                                 Yes, but does it?      Richard Erlacher      06/22/10 07:54      
                                    So have you looked at any other processors?      Per Westermark      06/22/10 09:37      
                                       not a point of disagreement, but you missed it anyway      Richard Erlacher      06/22/10 22:50      
                                          A good point      Justin Fontes      06/22/10 23:10      
                                             beg to differ      Michael Karas      06/22/10 23:23      
                                             Disagree entirely!      Andy Neil      06/23/10 00:45      
                                          Yes, auto-increment/decrement is standard and not "feature"      Per Westermark      06/23/10 00:29      
                                             What I wanted to point out ...      Richard Erlacher      06/23/10 06:07      
                                                Same same all the time. no "one size fits".      Per Westermark      06/23/10 07:46      
                                                   and the most important point is (drumroll) ....      Erik Malund      06/23/10 09:49      
                                                Comparing Apples to Oranges      Andy Neil      06/23/10 08:03      
                                          Prices are comparable      Andy Neil      06/23/10 01:00      
               Parallel processing        Oliver Sedlacek      06/22/10 02:40      
                  Sweeping generalisation!      Andy Neil      06/22/10 03:22      
                     Not a magic silver bullit      Per Westermark      06/22/10 04:20      
                        Fond memories      Oliver Sedlacek      06/22/10 07:58      
                        A magic bullet      Justin Fontes      06/22/10 10:17      
                           Most concepts already exists in the wild      Per Westermark      06/22/10 11:31      
                           Another generalisation        Andy Neil      06/22/10 14:43      
                           Speed vs latency      Oliver Sedlacek      06/22/10 14:47      
                              Why 8051?      Andy Neil      06/22/10 15:08      
                                 Isn't it obvious?      Justin Fontes      06/22/10 23:17      
                                    ARM simpler than 8051      Oliver Sedlacek      06/23/10 00:21      
                                       Generalisation      Andy Neil      06/23/10 01:34      
                                          ARM 'MCUs' have their limitations too!      Valentin Angelovski      06/24/10 07:52      
                                             You normally engineer with a backup plan      Per Westermark      06/24/10 08:20      
                                    No, it's not!      Andy Neil      06/23/10 01:27      
                                       Im just trying to provide an argument      Justin Fontes      06/23/10 10:33      
                                          x bits are just one parameter among many      Per Westermark      06/23/10 11:27      
                                             Avoiding the issue      Justin Fontes      06/23/10 21:09      
                                                Avoiding what issue?      Per Westermark      06/24/10 03:10      
                                          They say it because it's true!      Andy Neil      06/24/10 00:59      
                                          RE: ARM is not the only 32-bitter      Andy Neil      06/24/10 01:15      
                                    Please don'g generalize      Per Westermark      06/23/10 01:28      
                                 Heterogenous multiprocessing widespread      Oliver Sedlacek      06/23/10 00:17      
                  Re: Multicore 8051      Valentin Angelovski      06/24/10 06:48      
                     ALU chaining      Oliver Sedlacek      06/24/10 06:57      
   Well... maybe      Jez Smith      06/18/10 14:47      
      A Linear Accelerator?      Joseph Hebert      06/18/10 15:28      
         Its one of these      Jez Smith      06/18/10 15:51      
      please, repeat      Stefan KAnev      06/19/10 04:56      
         All I was saying was      Jez Smith      06/19/10 10:39      
   So what the '51 are good for...      Jan Waclawek      06/21/10 13:54      
      Not terribly helpful      Andy Neil      06/21/10 14:46      
         Always up to the developers      Per Westermark      06/21/10 15:24      
            RE: The manufacturers tells us...      Andy Neil      06/21/10 15:30      
               Sales - "may be used for" presented as "recommended"      Per Westermark      06/21/10 16:41      
               pretty hot, low-power and small      Maarten Brock      06/22/10 15:17      
                  Automotive...      Andy Neil      06/22/10 15:26      
         but answers your original question (at least the one...      Jan Waclawek      06/22/10 10:19      
         MCS51 still rocking !!!      Kiran V. Sutar      06/23/10 05:14      
            Scale      Andy Neil      06/23/10 06:09      
            Missing the point      Andy Neil      06/23/10 06:21      
               Impossible to generalize into fields      Per Westermark      06/23/10 08:09      
                  An appropriate generalisation...      Andy Neil      06/23/10 10:20      
               You are right..Andy Neil      Kiran V. Sutar      06/24/10 05:27      
                  Cheers!      Andy Neil      06/24/10 05:43      
                     No..only AT89C52 can be used      Kiran V. Sutar      06/24/10 05:56      
                        why do you insist on Atmel?      Erik Malund      06/24/10 06:05      
                        what a strange post      Erik Malund      06/24/10 06:09      
                        Tools?      Andy Neil      06/24/10 07:12      
                           Multiple manufactuers with (almost) identical chips      Per Westermark      06/24/10 07:48      
                              Getting better      Andy Neil      06/24/10 08:52      
                                 Unified interrupt controller is really great      Per Westermark      06/24/10 09:28      
                           Yes, even with free tools for PIC/AVR      Kiran V. Sutar      06/24/10 08:38      
                              I mean no offense, but ...      Richard Erlacher      06/26/10 09:59      
                              Similar difficulties coming to 8051/2?      Andy Neil      06/26/10 10:28      
                                 Same same      Per Westermark      06/26/10 11:18      
                  Is it your purchase price or why so sure AVR or PIC are off?      Per Westermark      06/24/10 05:55      
                     Answer to Per and Erik...      Kiran V. Sutar      06/24/10 06:38      
                  Living in the past      John D. Maniraj      06/24/10 09:44      
                     Thanks John D. Maniraj      Kiran V. Sutar      06/25/10 03:54      
                     locking      Erik Malund      06/25/10 07:20      
                        RE: Locking      Andy Neil      06/25/10 07:32      
                        Agreed, but      John D. Maniraj      06/25/10 11:00      
                           fairly easy      Erik Malund      06/25/10 11:53      
      Don't forget consumer devices      David Good      06/24/10 13:45      
         A perfect application      David Good      06/25/10 10:49      
   8051 vs ARM      Valentin Angelovski      06/24/10 08:34      
   just thought of one case      Erik Malund      06/24/10 12:32      

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