RAM comparison -- SX28, BS2, and the Propeller 1

LoopyBytelooseLoopyByteloose Posts: 12,537
edited 2014-12-21 - 18:25:19 in Microcontrollers
Just for everyone's info.

BS2 - Has 32 bytes for variable, pretty much the same as RAM space
SX28 - Has 136 bytes of RAM registers
Propeller 1 - Has 32K byte of HubRAM for combined use of program images and variables.

Advantages on the Propeller 1 are that one can creat huge lookup tables (such as to generate a specific motion cycle on a stepper motor). Or one can create a Forth Dictionary (which seems to need at least 16K bytes to get started)

The SXes, when programed in ASM are certainly more useful than the BS2. But the Propeller 1 runs circles around both the BS2 and SX chips.
Hwang Xian Shen, Puddleby-on-the-Marsh.
All things considered, I can live and thrive without Microsoft products. LINUX is just fine.

Comments

  • 4x5n4x5n Posts: 716
    edited 2014-12-13 - 16:04:37
    Just for everyone's info.

    BS2 - Has 32 bytes for variable, pretty much the same as RAM space
    SX28 - Has 136 bytes of RAM registers
    Propeller 1 - Has 32K byte of HubRAM for combined use of program images and variables.

    Advantages on the Propeller 1 are that one can creat huge lookup tables (such as to generate a specific motion cycle on a stepper motor). Or one can create a Forth Dictionary (which seems to need at least 16K bytes to get started)

    The SXes, when programed in ASM are certainly more useful than the BS2. But the Propeller 1 runs circles around both the BS2 and SX chips.

    I do disagree a bit with you about the Propeller1 running circles around the SX or that it's even more useful than a basic stamp. I'm not being contrarian <SP> here. Over the years I've become more and more convinced that different problems are best solved with different solutions.

    Over the years I've used a lot of SX processors in projects that were better solved with an SX than a propeller. For other projects I used a propeller and couldn't have done it with a single (or multiple) SX procs. The fact is that the SX procs are cheap and runs at 50mips!
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-12-13 - 21:08:51
    Yes they run at 50mips and maybe even 75mips. But the faster you go, the hotter they run. And the more power they drain.

    I'd say the big drawback with the Propeller is that you either have to go to a surface mount construction or live with a 40 Pin DIP for small projects. For a small project that needs a small footprint, the SX does offer advantages. For a project that needs all 5VDC, the SX offers advantages.

    My main reason for comparison is some people new to all three are not aware of the big difference in RAM resources.

    Personally, I am fond of all three - the BS2, the SXes, and the Propeller.

    But the Propeller can provide full-duplex serial at higher baud rates. 136 bytes is not much when you require buffers for fast burst of speed.

    And if you desire IR remote control, you pretty much have to locate a Sony 12-bit device for the SX and BS2; whereas the Propeller will accept any IR device with data as wide at 32-bits (This is what is on the market for an Arduino solution, an NEC 32bit device.)
    Hwang Xian Shen, Puddleby-on-the-Marsh.
    All things considered, I can live and thrive without Microsoft products. LINUX is just fine.
  • User NameUser Name Posts: 1,451
    edited 2014-12-20 - 22:08:08
    4x5n wrote: »
    The fact is that the SX procs are cheap and runs at 50mips!

    Absolutely. Whenever starting a new project, the SX is the first chip I consider. Small, fast, cheap, one-cycle interrupt latency, simple architecture and instruction set - all make it very desirable. Usually it is word size that ultimately decides the direction I go: Some jobs are miserable to implement in eight bit chunks. The Propeller is wonderful in such cases.

    BTW, I'm delighted there's an SX forum again. :)
    Platåberget
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-12-21 - 00:03:05
    I am also happy that the SX forum is where it can be seen.

    I just revived an SX-28 project that I have long wanted to complete.

    I am taking an 8X8 Red LED matrix and attempting to use it as a touch sensor to provide an alternative to an actual joystick. This requires a cycle that polls all 64 LEDs in a mode where they generate light.

    And then, the data can be sent at 19200baud *N1 in an 8 byte packet via RS422 or RS232 to regular computer or a Propeller to observe and use. I figure I will use 20Mhz as I don't need 50Mhz.

    If the device works well, it could be adapted to be an input device for a Propeller or just about anywhere a joystick might be required (if there is adequate ambient light).
    Hwang Xian Shen, Puddleby-on-the-Marsh.
    All things considered, I can live and thrive without Microsoft products. LINUX is just fine.
  • PublisonPublison Posts: 10,790
    edited 2014-12-21 - 08:08:42
    User Name wrote: »
    Absolutely. Whenever starting a new project, the SX is the first chip I consider. Small, fast, cheap, one-cycle interrupt latency, simple architecture and instruction set - all make it very desirable. Usually it is word size that ultimately decides the direction I go: Some jobs are miserable to implement in eight bit chunks. The Propeller is wonderful in such cases.

    BTW, I'm delighted there's an SX forum again. :)

    The SX forum never went away. Maybe it was buried in some sub forum.
    Infernal Machine
  • 4x5n4x5n Posts: 716
    edited 2014-12-21 - 18:25:19
    User Name wrote: »
    Absolutely. Whenever starting a new project, the SX is the first chip I consider. Small, fast, cheap, one-cycle interrupt latency, simple architecture and instruction set - all make it very desirable. Usually it is word size that ultimately decides the direction I go: Some jobs are miserable to implement in eight bit chunks. The Propeller is wonderful in such cases.

    BTW, I'm delighted there's an SX forum again. :)

    The SX may have been discontinued but it's far from being obsolete! It has a number of very important advantages to a lot of chips. It's very fast and has a reasonable number of IO pins. Use it as the PIC that it was designed to be and it does a great job.
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