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XTAL1 + pll16x issues — Parallax Forums

XTAL1 + pll16x issues

Sabre00Sabre00 Posts: 30
edited 2010-05-10 16:37 in Propeller 1
I tried looking through older posts but I was unsuccessful in finding an answer. Apologies if I am asking an already answered question.

I have been using a Propeller Demo board for a project I have and I have finally gotten to a stage where I would like to transfer it to a stand alone setup.

I am using veroboard for now but plan to design my own board at some point in time.

The problem I am having is, when I download the code as is on my board it does not work I return to the the demo board and it works fine. It took me a
while to find out the problem but it was the clock setup.

when I use
CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000



it does not work but when I make the clock mode anything less then pll16x it works sometimes. Anything pll1,2 and 4 work for sure. pll8x is a bit hit or miss.

I got the crystal from Parallax and it has on the same markings as the PropStick and that also takes the pll16x command.

Could it be my vero board? Should I skip this stage and go straight to PCB?

Mind you the code would work with pll2x but I was just wondering what the matter could be.

Sabre00...

Comments

  • RaymanRayman Posts: 14,887
    edited 2010-05-06 19:45
    What exactly works or doesn't work with pll16x?

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  • Bill HenningBill Henning Posts: 6,445
    edited 2010-05-06 19:47
    I suspect the problem is one of:

    - extra capacitance due to the vero board
    - bad socket, or bad solder joint
    - or bad wire wrap connection).
    Sabre00 said...
    I tried looking through older posts but I was unsuccessful in finding an answer. Apologies if I am asking an already answered question.

    I have been using a Propeller Demo board for a project I have and I have finally gotten to a stage where I would like to transfer it to a stand alone setup.

    I am using veroboard for now but plan to design my own board at some point in time.

    The problem I am having is, when I download the code as is on my board it does not work I return to the the demo board and it works fine. It took me a
    while to find out the problem but it was the clock setup.

    when I use
    CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000



    it does not work but when I make the clock mode anything less then pll16x it works sometimes. Anything pll1,2 and 4 work for sure. pll8x is a bit hit or miss.

    I got the crystal from Parallax and it has on the same markings as the PropStick and that also takes the pll16x command.

    Could it be my vero board? Should I skip this stage and go straight to PCB?

    Mind you the code would work with pll2x but I was just wondering what the matter could be.

    Sabre00...
    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.mikronauts.com E-mail: mikronauts _at_ gmail _dot_ com
    My products: Morpheus / Mem+ / PropCade / FlexMem / VMCOG / Propteus / Proteus / SerPlug
    and 6.250MHz Crystals to run Propellers at 100MHz & 5.0" OEM TFT VGA LCD modules
    Las - Large model assembler Largos - upcoming nano operating system
  • Sabre00Sabre00 Posts: 30
    edited 2010-05-06 19:47
    The program itself. It just stalls.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-05-06 19:47
    It's not the crystal or any capacitive effect of the Vero board. Regardless of the setting for the PLL, the crystal oscillates at 5MHz and the PLL generates a 16x signal, even if it's not tapped for use by the system clock. My suspicion is that you have inadequate bypassing on your Vdd/Vss pins. Can you show us a schematic and a photo or image of your layout?

    -Phil
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2010-05-06 19:55
    On your prototype have you connected both of the VDD pins and both the VSS pins or just connecting one of each?

    What are you using for power and how is that connected to the Propeller? Is your PS stable?

    Is there any filtering caps across the VDD and VSS pins right near the chip?

    Robert
  • Sabre00Sabre00 Posts: 30
    edited 2010-05-06 20:02
    I Think I uploaded the right one...
    IMG00676-20100506-1557.jpg
    1600 x 1200 - 393K
  • Sabre00Sabre00 Posts: 30
    edited 2010-05-06 20:05
    RobotWorkshop --> Connected both of them. I am using 22 gauge single core wire. Also I have a 12 V battery (SLA) and that is connected to a 7805 regulator and then a 3.3V regulator. No filtering capacitors. Took the schematic straight from the manual.
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2010-05-06 20:11
    Can you post a picture of the back of the board too? Is that board setup with the long copper foils that run the length of the board? If so have they be trimmed shorter for the crystal?

    Even though the schematic you used may not show any caps on the voltage regulators they should be there and the datasheets for many of the regulators will show them. I believe some of the regulators actually require them. If in doubt try to find the datasheet on the exact regulators used on your board.

    Robert
  • Bill HenningBill Henning Posts: 6,445
    edited 2010-05-06 20:17
    I think Phil and RobotWorkship nailed it.

    I'd add a 10nF or 100nF ceramic between Vcc and Vss on each side of the propeller, and also a 10uF-33uF electrolytic or tantalum on each side between Vcc and Vss. I'd also add a 100nF ceramic and a 33uF-100uF electrolytic at the output of the voltage regulator, and a 100nF decoupling cap at the eeprom.
    Sabre00 said...
    I Think I uploaded the right one...
    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.mikronauts.com E-mail: mikronauts _at_ gmail _dot_ com
    My products: Morpheus / Mem+ / PropCade / FlexMem / VMCOG / Propteus / Proteus / SerPlug
    and 6.250MHz Crystals to run Propellers at 100MHz & 5.0" OEM TFT VGA LCD modules
    Las - Large model assembler Largos - upcoming nano operating system
  • Sabre00Sabre00 Posts: 30
    edited 2010-05-07 06:57
    Thanks for all the comments. I will add the capacitors across the output voltages
    and ground.

    Yes the copper tracks run along the length of the board. I will break the tracks and let you
    guuys know. I will take before and after pictures but I suspect it may be the excess track length.

    Sabre00...
  • Sabre00Sabre00 Posts: 30
    edited 2010-05-07 13:15
    UPDATE!

    I somehow managed to forget my phone home so I can't take a picture of the back of the board just yet.

    However, I first cute the tracks and made them as short as possible and was able to get the code to run with pll8x.
    I then placed the coupling capacitors across the 5V and the 3.3V regulators and I was able to get the code to run with pll16x multiplier

    This then created another problem!

    I am using the USB2SER module to communicate with a PC and I was looking at the schematics of the propplug and the USB2SER and they differ by 1 pin
    so I decided to give it a try and I was able to download the program to the Propeller using the USB2SER module (Rev B or C). I was all happy then when
    I detached it from the PC's USB port, everything stopped. This was using the xtal1 + pll16x clock mode. However, when I change it to RCFAST I can still
    download the program and it runs when I disconnect the PC from the device.

    I was getting similar issues with the PropStick...

    a confused, but happy Sabre00...
  • Sabre00Sabre00 Posts: 30
    edited 2010-05-10 12:08
    Yet another update gentlemen.

    I managed to get the propeller working all by itself then I tried to incorporate another device with it that uses 5V and I somehow managed to fry my propeller and the device itself.

    I checked back my circuit and don't know why they won't work together.

    I plan to purchase a pre-built board assemble and populate that one.

    Time is against me so I will have to press on with this option.
  • RaymanRayman Posts: 14,887
    edited 2010-05-10 16:37
    I'd recommend starting with a Protoboard, if that would work for you...

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    My Prop Products:· http://www.rayslogic.com/Propeller/Products/Products.htm
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