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Will 10 Mhz crystal work with propeller? — Parallax Forums

Will 10 Mhz crystal work with propeller?

logan996logan996 Posts: 281
edited 2010-04-09 05:54 in Propeller 1
Hi, will this crystall work with the propeller? http://www.goldmine-elec-products.com/prodinfo.asp?number=G13554·and if it will than won't the propeller operate twice as fast a with a 5Mhz crystal?

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Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-04-08 22:59
    A 10MHz crystal will work with the Propeller, but only up to 80MHz (PLL8X). The faster PLL setting (PLL16X) won't work without active cooling of the Propeller. Look at the graphs of maximum system clock speed vs. chip temperature and supply voltage.

    The SpinStamp and the Hydra both use 10MHz crystals.
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-04-08 23:20
    10mhz will gain you nothing as you will run at 8x = 80mhz
    and that is the same as a 5mhz xtal at 16x = 80mhz

    You can run a 6.250xtal and get 6.25 x 16 = 100mhz
    these xtals are 1.25 each.

    Or use a 6.00mhz xtal and get 96mhz

    I ordered some new xtals a few days ago...they have not arrived yet
    but they cost .23 each. I got some 6.000 and even a few 6.400
    to see how they will work with the prop. 6.400 may be asking too
    much but the prop just might manage to run at 16x 6.400

    HEX0MfyQ.jpeg
    www.taydaelectronics.com/servlet/the-Crystals/Categories
  • Cluso99Cluso99 Posts: 18,069
    edited 2010-04-09 02:20
    I use a 6.5MHz xtal for 104MHz on the RamBlade and 13.5MHz * 8 seems to work reliably too, although not fully tested yet. However, for these values to work properly you require a clean pcb design.

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    · Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
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  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2010-04-09 03:10
    As I have mentioned in another thread I have been using these cylindrical crystals without any problems whatsoever.
    search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=300-8426-ND&x=0&y=0

    The reason I use 10MHz is because they are more readily available then the 5MHz values. Digikey seem to have fractional 6MHz values in stock as well. One off price is 63c but if you buy 100 (why wouldn't you) the price is only 36cents each.

    An advantage that the through-hole crystal has over the HC49 style is that the crystal takes up not only less room on the pcb but also less in copper real-estate. The HC49 has contacts that are huge and awkward to place close to the Prop chip yet the cylinder style just needs 2 little holes that you can place right next to the Prop and that doesn't get in the way of other pins. Compare two similar pcbs that I did and you can see the HC49 had to go on the other side of the pcb because it could not be placed close to the Prop without blocking all the pin connections. I didn't place the cylinder style crystal as close to the Prop in this pcb because it was a very crowded pcb.

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  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-04-09 04:06
    A crystal is just a crystal is not just a crystal. A reminder: the Propeller requires parallel resonant fundamental crystals of a certain capacitance, depending on frequency. Series-resonant or overtone crystals may not work properly and, if they do, can be off-frequency.

    -Phil
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2010-04-09 05:54
    @Peter Jakacki

    Those tiny round xtals look pretty good.

    .37 each if you buy 100 of them....not a bad price either.

    I think I will try a few of them.
  • @Peter Jakacki

    Hi Peter,

    Should PWM be working with the latest Forth and Extend? I am using:

    MODULES LOADED:
    1A81: EXTEND.fth Tachyon Forth Propeller hardware debugger and explorer - 150902-0100

    VER: Propeller .:.:--TACHYON--:.:. Forth V27150902.0100
    FREQ: 80MHZ (PLLEN OSCEN XTAL1 PLL16X)
    NAMES: $5491...7163 for 7,378 bytes (+125)
    CODE: $0924...4482 for 15,198 bytes (+1,309)
    CALLS: 315 vectors free
    RAM: 4,111 bytes free
    BUILD: FIRMWARE BUILD DATE 654545:466585
    BOOTS: 1
    BOOT: EXTEND.boot
    POLL:

    I then load this code:

    TACHYON [~


    : motor.FTH ." Motor driver for Jimmy the mouse bot " ;

    {
    Motor driver for Jimmy the mouse bot.
    Using L298 compact motor driver H bridge - Solarbotics

    P26 enable right motor
    P27 enable left motor

    P22 L1
    P23 L2

    P24 L3
    P25 L4

    start with initpwm to initialize the PWM
    }

    DECIMAL
    \ 1 - allocate memory for a table
    256 LONGS pwms \ allocate a 256 longs table for the PWM samples

    : initpwm
    \ 2 - specify the outputs and the address of the table then the freq and start the PWM cog
    \ Start up PWM using from P0..7, P16..P23 for 16 channels
    \ PWM.START ( iomask table freq -- )
    \ %00000110_00000000_11111111_11111111

    %00001100_00000000_00000000_00000000 pwms 6000 PWM.START
    ;

    : driveahead
    \ 3 - set the duty cycle for individual pins or groups of pins
    100 % 26 SETPWM
    100 % 27 SETPWM
    \ motors drive ahead
    \ left motor
    #P22 LOW
    #P23 HIGH
    \ right motor
    #P24 LOW
    #P25 HIGH
    ;

    : drivebackw
    \ drive backwards
    100 % 26 SETPWM
    100 % 27 SETPWM
    \ left motor
    #P22 HIGH
    #P23 LOW
    \ right motor
    #P24 HIGH
    #P25 LOW
    ;

    : driveleft
    100 % 26 SETPWM
    90 % 27 SETPWM
    \ motors drive ahead
    \ left motor
    #P22 LOW
    #P23 HIGH
    \ right motor
    #P24 LOW
    #P25 HIGH
    ;

    : driveright
    90 % 26 SETPWM
    100 % 27 SETPWM
    \ motors drive ahead
    \ left motor
    #P22 LOW
    #P23 HIGH
    \ right motor
    #P24 LOW
    #P25 HIGH
    ;


    \ tank style on place turning

    : turnright
    50 % 26 SETPWM
    50 % 27 SETPWM
    \ motors drive ahead
    \ left motor
    #P22 LOW
    #P23 HIGH
    \ right motor
    #P24 HIGH
    #P25 LOW
    ;

    : turnleft
    50 % 26 SETPWM
    50 % 27 SETPWM
    \ motors drive ahead
    \ left motor
    #P22 HIGH
    #P23 LOW
    \ right motor
    #P24 LOW
    #P25 HIGH
    ;

    : drivestop
    \ switch motors off
    1 % 26 SETPWM
    1 % 27 SETPWM
    \ left motor
    #P22 LOW
    #P23 LOW
    \ right motor
    #P24 LOW
    #P25 LOW
    ;

    ]~
    END


    And run the following:
    initpwm ok
    driveahead ok
    drivestop ok
    turnright ok
    drivestop ok


    I have also tried
    motor.FTH
    initpwm ok
    driveahead ok
    drivestop ok
    turnright ok
    drivestop ok



    While the motors turn, there is no signs of PWM on P26 and P27, they are 100% on all the time.

    I have spent the last couple of days on this, tried the .24 Forth as well and older Extend.

    Any suggestions?

    many thanks

    Lee





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