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Why does everyone down the MCS-51 family?

Discussion in '8051/8951' started by Jon Wilder, Nov 18, 2011.

  1. Jon Wilder

    Jon Wilder Active Member

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    I mean sure...it's an old architecture but there's a reason why that architecture is still being used in lots of devices and why manufacturers are still making MCS-51 derivatives (such as the Atmel AT89S series). I personally think it's a workhorse uC with lots of good stuff in it.

    I guess what I'm asking is why is it that people tend to talk down a uC based on nothing more than how old its architecture is? IMHO just because something has been around awhile doesn't make it any more or less "good".
     
  2. Sceadwian

    Sceadwian Banned

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    Yes, and it's because there are many old applications that require it specifically automotive. These old applications refuse to change away from their stock chips and designs because of the chronic fear of any kind of change in automotive design, so makers still make compliant versions of them, it's not for any inherent superiority of the design.

    There are better designs and chips out there, if you're starting fresh you wouldn't consider a legacy chip like like the MCS-51 even with it's more modern upgrades (though they help) but start with a more refined modern design such as the more modern AVR or PIC line of controllers (among others)

    Everyone knows how useful a mule is even as they age, but you don't win the Kentucky derby on a mule, and if you're looking to start a new farm you don't by an old mule =) There are many more modern architecture's that are tried and true.

    It depends so highly on the application that I'm not sure who would put down the MCS-51 family, but it does belong in it's place, and new design isn't possibly the best place, unless you happen to have a designer that is very well versed in the chips, it's actually not just industries unwillingness to change but for programmers to continue to use previous designs because they've worked before. Shouldn't detract you from looking at new designs though.
     
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  3. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    I feel that the 'old' 8051/2's were brilliant little devices but now they seem to lack interface's.... I mean very difficult to get one with the kind of peripherals that AVR and PIC provide

    I used a XA51 from phillps.. good chip.. excellent memory connection...made a great datalogging unit for us. But I couldn't use it for anything else.. A0 to 23 and D0 to 7 it felt like a 'semi' microcontroller.
     
  4. dave

    Dave New Member

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  5. WTP Pepper

    WTP Pepper Active Member

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    These days everyone wants to use the latest sexy CPU with all its glory and peripherals. However like the Z80 core, the 8051 core has been around for over thirty years. Its shortcomings are known through extensive use in millions of applications over the years. That makes it a very reliable product. I personally will use anything with a 68000/8051/Z80 core for that reason because they are reliable architectures.
    When the Hubble telescope was last fixed, they used nothing more complicated than an i386 for the same reason. Why gamble on a new all singing processor when the i386 has been used in billions of PCs without any issues.
    The 8051 has been revised a few times to increase instructions/cycle, but the architecture largely remains the same.

    Apart for those pointless electric things, the car engine is much the same as Henry Ford invented and there is a good reason for that.....
     
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  6. nsaspook

    nsaspook Well-Known Member

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    I think the fact you could then buy rad-hard 386 "HUGE 1.5 micron line width" chips might have something to do with it also.

    http://www.cpu-galaxy.at/article/cpu_in_space.htm
     
    Last edited: Jan 28, 2012
  7. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    One of the reasons the 8051 is going strong is that it is (more or less) open source. You can build a 8051/52 in a FPGA or ASIC, add new instructions and not pay a fee. Many silicon houses use 8051s for that reason.

    SI Labs has 8051s that run 100 times faster than my first project. Some of the parts have more memory pointers, hardware multipliers, DSP instructions, and more. All the parts I have used recently have internal PROM, RAM, TIMERS, eepron, ADC, etc. I used one that came in a 2mm by 2mm package.

    Some 8051 hide under other names.
     
  8. Sceadwian

    Sceadwian Banned

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    Not so sure about that, I've seen open source AVR cores out there and I'm sure there are PIC versions as well.
     
  9. WTP Pepper

    WTP Pepper Active Member

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  10. Wond3rboy

    Wond3rboy Member

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    Hi Ian, although i am (very) proud PIC user but this is one option that provides a host of peripherals and other features and uses the 8051 core. Ofcourse cost might be an issue(their buy/sample form is not working for me so i cant get a quote)

    http://www.silabs.com/products/mcu/mixed-signalmcu/Pages/default.aspx
     
    Last edited: Feb 8, 2012
  11. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    Hi Wond3rboy... I totally agree.... A company I use (Ciseco) use a TI CC1101 from Texas Instruments.... It can do more than AVR and PIC (8 bit) put together, however the simulation and debugging facilities, unfortunately, for AVR and Pic, are plentyfull.. I use ISIS and I have the full pic model AND the 8051... No-one is writing for the 8051 so the chips cannot model any of the newer peripherals. This appears to be the case with many, as the PIc and AVR take a real good share..... The boys at Labcenter wouldn't even do me an I2C model on the 51 even though the chip was a current device.

    Its a shame... but there it is.
     
  12. duffy

    duffy New Member

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    I can remember when the 8051 was a step up from my 8049. Then it was the 68HC11. These days I'm using PICs. Reason is because, at some point, everyone winds up writing some little loop routine that needs to spin around madly fast - the faster the better - and it doesn't matter if the instructions are stupid PIC junk or reasonably sensible Intel assembler. The 8051 and the others needed extra cycles to do the same thing, so in a given amount of time the PIC could do more loops where it mattered and that was the main reason it won out.
     
  13. Wond3rboy

    Wond3rboy Member

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    Hi Ian, yeah TI has really gone that extra mile in incorporating the 8051 in to a lot of their devices(i have seen some of their wireless modules having the 8051 inside to make use easier). Their is definitely a bias going on by the simulator makers. I use ISIS too and should say that it has a large device library, but guess they follow industry trends, bet if silabs and other such manufacturers market their product well enough the simulator people will come up with better/more tools.
     

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