Shop OBEX P1 Docs P2 Docs Learn Events
My first stupid question... — Parallax Forums

My first stupid question...

Up2l8Up2l8 Posts: 8
edited 2005-09-24 09:30 in General Discussion
Armed and ready with my new·SX key and an assortment of chips, I am ready to enjoy my SX experience in all of its 75mhz glory!

Being new to the scene I am·sure to have several "stupid" questions... Hey, I'm a pic guy. i need re-educating confused.gif My first stupid question-

The 2k program space has me a tad concerned, I've generally worked with 8-14k pics.
How do·folks work around that?· Can SX chips load external instructions from an eeprom?

I know alot of resonses are likely to be "you would be surprised what you can do with 2k/4k if you program intelligently..."·and I'm sure I would.· But I still would·like to ask my stupid question tongue.gif

Eric

Comments

  • StephenStephen Posts: 53
    edited 2005-09-22 04:20
    There's really no way to execute from external memory directly. The SX doesn't present it's internal buses to the outside world. With an interpreter running on the SX then you can run from external code, but it will be a lot slower. The stamps are an example of that...
  • PJMontyPJMonty Posts: 983
    edited 2005-09-22 06:51
    Eric,

    Most of the time, worrying about too little code space before you start a project is like optimizing code before you finish writing the whole project - usually not necessary. What kinds of projects are you thinking of doing? If you have something that requires a ton of text, you may find a need for external memory to hold the strings. Also, writing in assembly will stretch the 2K of memory quite far.

    Anyway, start working on a project and then see if you run out of memory. If you do, post some specific questions here and I'm sure you'll find there are ways to save memory that you might not have thought of.
      Thanks, PeterM
  • BeanBean Posts: 8,129
    edited 2005-09-22 11:10
    Eric,
    You could also use the SX48/52 Proto boards. The SX48/52 has 4K of code and about twice the RAM of the SX28.

    But you can do alot in 2K for example the SX-Video module uses only the SX28, okay big deal, BUT the character dot patterns are using 896 of the 2K program space. And except for the video generation code, it's written in SX/B.

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "SX-Video·Module" Now available from Parallax for only $28.95

    http://www.parallax.com/detail.asp?product_id=30012
    Product web site: www.sxvm.com
    Available now... SX-Video OSD module $59.95 www.sxvm.com

    "I'm a man, but I can change, if I have to, I guess"
    Red Green
    ·
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2005-09-22 15:48
    Eric,

    have a look at this spec list for a DC motor controller:

    - PWM-control three full H-bridge power drivers for DC motors
    - Allow for reversing the motor's direction of rotation
    - Receive commands, and send status information via I²C
    - Monitor the status of reference and end-position sensors for all three motors
    - Count tacho pulses generated by the motors, and stop them when the requested target position has been reached
    - Check for over-current on the three motor supply lines
    - Check for "blocked" conditions, i.e. a motor is supposed to turn but no tacho pulses are generated
    - Check for "master-timeouts", i.e. no status information requested by the I²C master within a certain period of time
    - Do a "soft start", i.e. slowly increase the motor PWM signal's duty cycle from 0% up to the requested value
    - Drive an LED indicating the current status of the module

    I could implement all these features using an SX28 with its program memory limited to 2 kWords, and the available RAM space. I still have some free memory left for more features. I must admit, this was the most challenging project I ever did with an SX28 but it turned out to work w/o problems. In the meantime, I could produce and sell more than 300 of these controllers to one of my customers.

    I also have some PIC background (Atmel and other controllers as well) but I really like the SX because of its speed and flexibility. I'm pretty sure, you'll like it as well, so welcome to the club smile.gif .

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Greetings from Germany,

    Günther
  • Up2l8Up2l8 Posts: 8
    edited 2005-09-22 20:10
    After I posted I realized that it was indeed a stupid question since as Stephen mentioned the SX internal busses are not ported out.

    Thanks for the replies - usually when I run out of space it is font sets / bitmaps for LCDs and things like that.
    But·can always use·my 512K serial eeproms for that stuff.

    Does anyone know if there is any work being done to flesh out the SX line?· The chips that they have, while versatile, are begging to have brethren [noparse]:D[/noparse]

    Eric
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-09-22 22:09
    http://forums.parallax.com/showthread.php?p=548031

    will answer your question, the die is static.
    Ken Gracey said...
    But whatever we do, there will be no change to the SX silicon. The engineering on this chip is sealed for life and the fabrication process is producing high yield, reliable results.
    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·1+1=10
  • cbmeekscbmeeks Posts: 634
    edited 2005-09-23 18:42
    Guenther Daubach said...
    Eric,

    In the meantime, I could produce and sell more than 300 of these controllers to one of my customers.

    Just curious...how much would a unit cost?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    http://metroidclassic.com

    =========
    DMCA Sucks
    RIAA Sucks
  • Up2l8Up2l8 Posts: 8
    edited 2005-09-23 23:51
    Paul Baker said...
    http://forums.parallax.com/showthread.php?p=548031

    will answer your question, the die is static.
    Oho!· Guess we just need to wait for gen2 chips!

    Eric
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2005-09-24 09:30
    cbmeeks,

    one unit sells for US$ 160.00 + S/H.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Greetings from Germany,

    G
Sign In or Register to comment.