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Current state of C on Propeller 1? SimpleIDE? — Parallax Forums

Current state of C on Propeller 1? SimpleIDE?

I have the P1 on a breadboard with the minimal circuit from the manual.

With SimpleIDE, I could compile some examples but none would download to my Propeller. (PropellerTool works just fine.) Shouldn't this work out of the box? Or is SimpleIDE only for Parallax dev boards and none other?


  • I had the same issue, way back it did work but something got changed and since few people bread board there P1's it didn't get fixed.

    I did manage to load my code though but can't remember how I did it. I can't try it any more since shortly after that when I tried to move it to another bread board, I fried it and didn't bother replacing it since I now use a Propeller Mini for all my projects.


  • VonSzarvasVonSzarvas Posts: 2,560
    edited 2021-12-07 08:38

    Do you have an external crystal in your breadboard circuit ? That is essential for the SimpleIDE downloader.
    Also very close (to the P2 P1 chip) and short leaded 100nF ceramic capacitors between each of the VDD and VSS pins.
    And finally a bulk cap (maybe 10-100uF range) on the breadboard will help when the source power supply if a distance away.

    Feel free to post a photo of your breadboard setup if you'd like us to look for anything else that might be an issue.

  • The original post was for a P1, but all the concerns for capacitors still apply.

  • Thanks for the tips.

    PropellerTool works. Is there a way to make SimpleIDE work like PropellerTool? Like, can SimpleIDE use the same programmer that PropellerTool uses? If not, how do I use C on the Propeller in way that just works?

  • evanhevanh Posts: 12,185

    I'd guess Von meant the Prop1. So the statement "[A crystal] is essential for the SimpleIDE downloader." presumably means PropTool doesn't have that same requirement.

  • Oops! Yes,, must have had P2 on my mind whilst typing ! Post above corrected.

    As evanh said. The fast loader used by SimpleIDE requires the external crystal, whereas the slow loader used by PropellerTool relies only on the internal crystal.

    The requirement for crystals and decoupling capacitors is that they have very short leads and are as close as possible to the microcontroller. (This is a basic rule for any microcontroller).
    With breadboard setups, the breadboard itself can add significant distance between the microcontroller pin and the crystal or capacitor leg.
    Also, with the through-hole parts themselves, the legs can be very long.
    All that adds capacitance and inductance that throws the clock frequency out of specification and messes up timing sensitive processes, like high-speed programming.

    When installing the crystal and 100nF capacitors, the ideal scenario would be to cut the through-hole part legs to the shortest possible that they make contact in the breadboard, and use the breadboard holes directly adjacent to the microcontroller legs (if not the same holes as the microcontroller legs!). If you can do that, you will likely find SimpleIDE will work for programming.

    There could be other layout issues too, but difficult to guess without seeing how you've got things set up. If you try the above, please let us know if that helps you solve it! You have a very good chance.

  • @VonSzarvas ,

    I think what he wants is a loader for the P1 that works with the C compiler without the Crystal installed. I think the answer is no, you need to buy the 5 Mhz Crystal to be able to use the C compilers loader.

    Even though the code that is loaded is the same, the loader used with the SimpleIDE cannot load the code without the crystal. The C compiler was developed much later in the life cycle of the P1 and did not include a way to load the code without a crystal installed.

    The crystal is less than a $1 so not having one doesn't make sense.


  • evanhevanh Posts: 12,185
    edited 2021-12-07 14:21

    I was just recently looking at crystals for the Prop1 and discovered the 5-6 MHz crystals are all in large metal cans. But complete crystal oscillators in that frequency region can be very small SMD packages. Although an additional 10 nF capacitor is also required alongside. Prices are about the same.

    EDIT: PLL in x4 mode using a 20 MHz crystal I guess is an option. They're readily available as plain crystals in small SMD packages. Oh, no, that's right, the VCO in the PLL is always x16, with a divider after that. So can't use 20 MHz on XI unless leaving the PLL turned off - Which is an option given that RCFAST is only around 12 MHz without a crystal.

  • RaymanRayman Posts: 12,366

    I found some 5-MHz xtals in little tubes... Think from Seiko. Seemed to work.

  • You totally can disable the fastloader, something something in the board config file.

    Then again, running without crystal is kinda pointless. Though you'll still need to mess with the board config if you a crystal that isn't 5 MHz

  • @Wuerfel_21 ,

    I tried all kinds of options, none of them worked for me. Looking at the loader code the problem is the boot strap stub program expects there to be a crystal and fails.


  • Ah yes, SimpleIDE has propeller-load, not proploader and I don't think the former actually has the ROM loader option. I always confuse these.

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