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50 Mhz SMT Resonator — Parallax Forums

50 Mhz SMT Resonator

SailerManSailerMan Posts: 337
edited 2007-01-26 19:23 in General Discussion
I'm having a small problem with the 50Mhz SMT resonator on my own board.. I soldered one for use with an SX-48 and the SX run erratic, I removed the SMT Resonator and rigged a 3 pin receptical for the 50 MHZ Blue plug in Resonator... And now things are fine.. Is there a trick to the SMT type? I am assuming the Center Stripe is ground and the two ends are to OSC1 and OSC2 does it matter which end is which?

Thanks for any insight

Eric





Post Edited (SailerMan) : 1/26/2007 1:09:29 AM GMT

Comments

  • BeanBean Posts: 8,129
    edited 2007-01-26 01:00
    Eric,
    No it doesn't matter which end goes to OSC1 or OSC2.
    Try a different OSC setting Usually HS1 HS2 or HS3 (usually HS3 makes it overheat).

    Bean.

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  • SailerManSailerMan Posts: 337
    edited 2007-01-26 01:07
    OK I lied after about 5 mins the SX is running erratic, If I plug in the SX-KEY and take out the Resonator... The home made board run perfectly. I don't like intermittent problems. There has to be something simple I'm over looking... What is the main difference between the SX Key generating the 50Mhz and the Descrete resonator?

    My first two line for the SX48 are

    DEVICE SX48, OSCHS1,BOR42
    FREQ 50_000_000

    I am Testing OSCHS1 right now... OSCHS2 and 3 Did not work. What are the differences?
  • BeanBean Posts: 8,129
    edited 2007-01-26 01:20
    Eric,
    When the SX-Key drives the SX the internal oscillator (which causes the external resonator to resonate) is turned-off.
    The HS1 HS2 and HS3 setting determine how "hard" the resonator is driven.

    When I used HS3 my SX48 would run for a couple minutes then stop and it would be VERY hot. HS2 worked fine for me.

    Try some of the other OSC settings too XT1 XT2 etc.

    Bean.

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  • SailerManSailerMan Posts: 337
    edited 2007-01-26 01:20
    OK... After about 10 Mins It seems to be stable with OSCHS1.· Thanks Bean!!

    ·
  • BeanBean Posts: 8,129
    edited 2007-01-26 01:40
    Cool,
    Your welcome [noparse]:)[/noparse]
    If you put a current meter on the SX you will see a significant change between HS1, HS2, and HS3.

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
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    Low power SD Data Logger www.sddatalogger.com
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    "USA Today has come out with a new survey - apparently, three out of every four people make up 75% of the population." - David Letterman
  • SailerManSailerMan Posts: 337
    edited 2007-01-26 01:42
    Oh Darn after about 20 Mins it crapped out too!!

    In reading some documentation... Should I add capacitance from the Crystal to Ground?

    http://www.parallax.com/dl/docs/prod/datast/SX4852BD.pdf

    Page 25.... Looking at my SX-Tech board and the SX-48 Proto Board I don't see any additional components.
  • BeanBean Posts: 8,129
    edited 2007-01-26 01:57
    If you are using a three lead resonator, then it has the caps built-in.

    You could try putting a resistor across the two outside leads.
    Maybe 1Meg or 100K or 10K ??? Try different values.

    Are you running at 5 Volts ?

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
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    Low power SD Data Logger www.sddatalogger.com
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    "USA Today has come out with a new survey - apparently, three out of every four people make up 75% of the population." - David Letterman
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-01-26 01:57
    Hello,

    · Yes, we recommend a capacitor on the OSC2 pin to ground. Please see the following schematic for an example. You should use the value listed in the schematic. This makes the resonator/SX more stable, especially at higher frequencies by kind of unbalancing things. I hope this helps. Take care.

    http://www.parallax.com/dl/docs/prod/schem/BS2SXSchematicRevE.pdf

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
  • SailerManSailerMan Posts: 337
    edited 2007-01-26 02:38
    Thanks both... I only have 22PF ceramic disk ... With OSCSH1.. It Clocks too Slow so I'm moving to OSCHS2. (I'm trying now I hope this works) I will have to purchase some 33pf caps.
  • SailerManSailerMan Posts: 337
    edited 2007-01-26 03:15
    OK... Now the SX48 Runs for about 30 seconds then Stops for about 15 then picks up where it left off... It continually does this... When the KEy is in... It does not.

    Any more suggestions? [noparse]:)[/noparse] Please...[noparse]:)[/noparse] BTW I paralled two 22pf caps and it is still doing the same thing.
  • BeanBean Posts: 8,129
    edited 2007-01-26 03:26
    Eric,
    Sounds like something funky is going on. I often just connect the 50MHz resonator right to the SX without any other componets and adjust HSx. I stumped...

    Are you using 5 Volts ?
    Are the leads short from the SX to the resonator ?
    Can you try a different SX48 ? (maybe you got a bum one?)
    Can you post your entire DEVICE line ? (I (expletive)ume you are using TURBO, OPTIONX, STACKX also).
    Are you using the Parallax 50MHz resonator ?
    Does the SX48 chip get hot when it's misbehaving ?
    Are you sure the SX is actually stopping and it's not a bug in the code ?
    Can you put a current meter on it and see if the current changes when it's operating and when it's not ?

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Cheap used 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com
    SX-Video Display Modules www.sxvm.com
    Stuff I'm selling on ebay http://search.ebay.com/_W0QQsassZhittconsultingQQhtZ-1

    "USA Today has come out with a new survey - apparently, three out of every four people make up 75% of the population." - David Letterman
  • SailerManSailerMan Posts: 337
    edited 2007-01-26 03:44
    I am using 5 volts to power the SX48.

    The Resonator is within a CM.

    It'll be some work... to remove the SX and replace it... Thank god for Chip Quik... I'll try that as a last resort.

    I am not using " TURBO, OPTIONX, STACKX" because when I do I get a warning 51,p(expletive)1 , keyword is obsolete... For all three..

    Like you said it gets hotter if I use OSCHS3, What are you thinking here?

    I have a Serin command with a 100 MS timeout that is toggling an LED. The led Stops blinking. ( I just don't know why it doesn't have a problem when the Key is attached... That is why I haven't persued a code problem.

    I'm not sure where to attach my meter.

    Thanks for all of your help.

    (expletive) - It took me a while to figure this out... hahahah even if it is part of a normal word.· Funny!! The forum software should know the difference. [noparse]:)[/noparse]

    Eric

    DEVICE········· SX48, OSCHS2, BOR42
    FREQ··········· 50_000_000
    ID· "LED"

    Counter Var Byte

    PROGRAM Start NOSTARTUP

    Start:
    ··············
    Tris_E=%00000000
    Main:

    Do
    ·· Counter=Counter+1
    ·· RE=Counter
    ···IF cOUNTER>15 THEN
    ···· cOUNTER=0
    ·· ENDIF
    · Toggle RB.0
    · PAUSE 50
    Loop
    I just ran this program... It runs for a while and then stops. Then starts up again on it's own and continues like this.

    Post Edited (SailerMan) : 1/26/2007 4:01:59 AM GMT
  • BeanBean Posts: 8,129
    edited 2007-01-26 12:35
    What do you mean "The resonator is within a CM" ?

    Oh yeah the SX48 doesn't use "TURBO, STACKX, OPTIONX" I forgot about that.

    Hmmm, I'm baffled... Keep trying things, you're sure to find the problem.

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Cheap used 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com
    SX-Video Display Modules www.sxvm.com
    Stuff I'm selling on ebay http://search.ebay.com/_W0QQsassZhittconsultingQQhtZ-1

    "USA Today has come out with a new survey - apparently, three out of every four people make up 75% of the population." - David Letterman
  • SailerManSailerMan Posts: 337
    edited 2007-01-26 13:43
    I'm sorry... the resonator is within a centimeter.

    Darn I was hoping you'd have some magical solutions.. the thing that's got me is that it runs perfectly with the SX-Key. I'll keep plugging away.

    Do you think that the type of capacitor I'm using is the cause? Should I still place the 1Meg ohm resistor across OSC1 and OSC2?
  • SailerManSailerMan Posts: 337
    edited 2007-01-26 19:23
    Well, After messing around with this problem for a few hours... I decided that It must be the SX48, and it was. I replaced the bad chip and all is fine now.


    Edit.... It's not ok... Darn... There must be noise somewhere... It's the intermittance that is odd.

    Why will it work with the KEY and not the Resonator??????



    Post Edited (SailerMan) : 1/26/2007 9:00:05 PM GMT
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