Shop OBEX P1 Docs P2 Docs Learn Events
SX52 75MHz — Parallax Forums

SX52 75MHz

RsadeikaRsadeika Posts: 3,837
edited 2005-12-09 02:56 in General Discussion
Testing out my SX52 proto board, I ran into a weird situation. In stand-alone, when I run my LED on/off program, which has a·PAUSE 1000 command,·freq set at 4MHz, and 50MHz, the program runs as expected. When I run it at 75MHz (using a Parallax brand oscillator), the LED never turns off. The PAUSE command has no affect, or something else is happening. Anybody else run into a problem like this. Any ideas as to what is going on?

Thanks

Comments

  • Ken GraceyKen Gracey Posts: 7,401
    edited 2005-12-07 21:50
    Rsadeika,

    You know what you're going to get for a reply - "post your code, please"!
    • I wonder if SX/B handles the PAUSE timing adjustments·at 75MHz.
    • Pretty certain you're not in a DEBUG mode and letting the clock cycles count in an endless loop?
    • How about the directive at the top of your program? What does it look like?

    I've not programmed the SX very much, so my responses are mostly based on what I've read on this forum.

    Ken Gracey
    Parallax, Inc.
  • RsadeikaRsadeika Posts: 3,837
    edited 2005-12-07 21:57
    Here is the code, it's pretty straight forward. Maybe somebody can make some coding suggestions for the SX52 programs.



    *****code

    ' =========================================================================
    '
    '·· File...... SX52test1.SXB
    '·· Purpose... SX/B Programming Template
    '·· Author....·
    '·· E-mail....·
    '·· Started...
    '·· Updated...
    '


    '
    ' Program Description
    '


    '
    ' Device Settings
    '

    DEVICE········· SX52, OSCHS3
    FREQ··········· 75_000_000


    '
    ' IO Pins
    '
    led1 var rd.0

    '
    ' Constants
    '


    '
    ' Variables
    '



    ' =========================================================================
    · PROGRAM Start
    ' =========================================================================


    '
    ' Subroutine Declarations
    '
    LEDON sub

    '
    ' Program Code
    '

    Start:
    · ' initialization code here

    Main:
    '· TRIS_D=0
    ·' RD.0 = 0
    ·LEDON···· 'Turn the LED on/off

    END
    '
    ' Subroutine Code
    '
    LEDON:
    ·TRIS_D = 0
    ·led1 = 0
    ·pause 1000
    ·led1 = 1
    ·pause 1000
    return
  • David BDavid B Posts: 592
    edited 2005-12-08 00:56
    I've had problems with a wall-wart power supply that was rated at what seemed like good voltages and currents, but when using it, my SX52 proto board would occasionally fail to start oscillating, even though when I'd measure the incoming voltage it seemed good enough. Maybe starting the SX oscillating requires a big current surge?

    When I switched to a much more robust power supply, all the starting problems went away.

    Is your power supply able to handle the increased power draw at 75 mHz?

    David
  • RsadeikaRsadeika Posts: 3,837
    edited 2005-12-08 16:20
    I did some more stand-alone·testing on my SX52 proto board. By mistake a did not plug the oscillator in, I plugged in my 6v 4.0Ah battery and, my LED on/off program·seem to work. The funny part is, how could this occur since I did not have a crystal/oscillator source. Then I put in an·oscillator and ran the program, no LED (for my program) goes on.·Now I wonder if I trashed my proto board. At this rate maybe I should order another dozen or so of the boards. LOL

    Anybody have an explanation why my LED turned on·with no crystal/oscillator source. If, indeed this power thing is related to the problem, does anybody have a power requirement number for running a 75MHz oscillator on the proto board.

    Just thought of something, is there an oscillator orientation concern, can the oscillator be placed onto the proto board in any position? I noticed on the bottom side of the oscillator there are three blue dots, on the top side there looks like a white dot, anybody know anything about those things.

    Thanks

    Post Edited (Rsadeika) : 12/8/2005 5:21:11 PM GMT
  • RsadeikaRsadeika Posts: 3,837
    edited 2005-12-08 19:59
    EDIT
    I think I solved the problem, It looks like it is an oscillator orientation concern. On the oscillator there is a marking, I guess it is an orientation mark. Learn something new everyday. I guess I did not fry my oscillator after all, maybe shortned the life span a bit. Just checked on battery source, and so far it looks good.

    Now back to I2C.

    Post Edited (Rsadeika) : 12/8/2005 8:33:38 PM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-12-08 20:23
    This is actually the opposite of what I would expect had this been a power issue, since the SX-Key uses a chunk of power...So having it would increase power demand and the possibility of sagging.· Interesting...



    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • RsadeikaRsadeika Posts: 3,837
    edited 2005-12-08 20:36
    I guess I did not edit fast enough, read my previous post.
  • RsadeikaRsadeika Posts: 3,837
    edited 2005-12-08 21:12
    Not so fast,

    After running for a couple of minutes, I did the finger test on all the parts on the board. I noticed that the SX52 chip was getting hot, not finger blistering hot, but can't leave the finger on the chip, hot. Since I am looking for a 24/7 board operation, does anybody know if the chip will cook off at 75MHz after an extended time of use. I was·expecting some heat concerns at 100MHz, but not at 75MHz. Anybody have any heat data for the SX52 chip. In other words should I be concerned with my finger test.

    Thanks
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-12-08 23:35
    Well, 50 Mhz is pretty darn fast...The chip could get pretty warm.· 75 Mhz is toward the top of the speed range of the SX, and you may or may not need to implement some cooling procedures based·on the environment.· In other words if this is sealed into a cabinet you might want to implement a cooling fan into the case.· If it's sitting open-air, it should be okay.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • BeanBean Posts: 8,129
    edited 2005-12-09 00:55
    As a rule of thumb[noparse];)[/noparse] if you cannot leave your finger on the part, it's probably too hot.
    I would look at adding a heatsink of some kind.
    Bean.

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

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    Those that would give up freedom for security will have neither.
    ·
  • dkemppaidkemppai Posts: 315
    edited 2005-12-09 01:57
    Bean (Hitt Consulting) said...
    As a rule of thumb[noparse];)[/noparse] if you cannot leave your finger on the part, it's probably too hot.
    I would look at adding a heatsink of some kind.
    Bean.

    So, you mean my running molten solder·temperature test·was probably pushing the limit, huh? (Yes, you read it correctly,·operation with liquid solder...)

    -Dan


    ·
  • BeanBean Posts: 8,129
    edited 2005-12-09 02:05
    Ah, you lost me... Do you mean that the chip melted solder ? Or you put melted solder on it to see if it would stay working ?
    I have seen chips get hot enough to de-solder themselves.
    Bean.

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

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    Those that would give up freedom for security will have neither.
    ·
  • ForrestForrest Posts: 1,341
    edited 2005-12-09 02:08
    You might try a penny as a heatsink - discussed here a few days ago http://forums.parallax.com/showthread.php?p=559461
  • dkemppaidkemppai Posts: 315
    edited 2005-12-09 02:31
    Bean (Hitt Consulting) said...
    Ah, you lost me... Do you mean that the chip melted solder ? Or you put melted solder on it to see if it would stay working ?
    I have seen chips get hot enough to de-solder themselves.
    Bean.

    I mean an ambient operating enviornment (Air temp·> 180C) hot enough to melt solder...
  • BeanBean Posts: 8,129
    edited 2005-12-09 02:56
    Yeah, that might by pushing the spec a little.
    At my work we routinely test our products from -55°C to 125°C and I though that was extreme.
    And not just functioning, they must be meet spec over that temperature range.
    One day I'm gonna test my video modules to just see what range they will work over.
    Bean.

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

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    Those that would give up freedom for security will have neither.
    ·
Sign In or Register to comment.