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Notes On Propeller (might be helpful for new user ) — Parallax Forums

Notes On Propeller (might be helpful for new user )

Attached Word document with navigation bar might help with syntax look up for propeller has essentially what has been previously documented on Parallax site but includes examples might help new users waiting for Propeller manual.

Comments

  • Very nice Bob! :smiley:

  • PublisonPublison Posts: 11,966

    Very nice doc, Bob!

  • Updated "Hello Propellwe 2 Examples Rev02.docx" and added the example program files. docx is at bottom of zip file list
    RegardsB
    Bob (WRD)

  • evanhevanh Posts: 11,290
    edited 2021-07-16 10:51

    Bob,
    That's a lot of effort you've thrown in! You're picking up plenty of good details too.

    Are you doing this for Parallax? They are beavering away on docs right now themselves.

    PS: Section 4.1 "P2 Uses a Voltage Divider approach." ... I should point out the first figure is also a voltage divider circuit. The main difference is the Prop2 uses a more robust and faster acting arrangement that doesn't have the buffering op-amp. Therefore the output is pure resistive, hence why the output resistance is specified. I think it also has the side effect of better linearity as well but that's just a guess from me.

    PPS: Looking it up, the first figure is called a "binary weighted resistor" DAC. Linearity of that type becomes a major issue at higher word sizes. The "R-2R ladder" DAC is effectively the same but greatly improves on the linearity.

    Prop2 uses what's called a "Thermometer coded" or "Unary coded" DAC. A name I've never bumped into before but then I'd not seen the exact method either. It's pretty heavy on real-estate but does deliver high precision at speed.

  • evanhevanh Posts: 11,290
    edited 2021-07-16 11:29

    Prop2's ADCs are what's called a "sigma-delta modulator" or "delta-sigma modulator". Just a single fast comparator with feedback, which oscillates in the MHz, producing a natural bit-stream known as pulse-density-modulation (PDM). This is subsequently vacuumed up by a counter configured as a "Sinc filter/decimator" from which you then get your typical PCM samples.

  • Thanks for reply. I will add your comments into the document for future revision. I am not doing this for Parallax who will do a better job when then get around to the docuentation, but anyone who wants to use it can. I am retired and I think the propeller II has so much poetential for learning .
    Regards
    Bob (WRD)

  • Most recent revision see docx file examples updated
    Regards
    Bob (WRD)

  • MaciekMaciek Posts: 372
    edited 2021-07-26 07:01

    Valuable information inside. Thank you.
    May I suggest updating the first post with the newest doc file and commenting the changes within the consecutive posts ?
    This way one will always have the newest document version at the top and the newest comments detailing the changes as they come in the posts.

  • PublisonPublison Posts: 11,966

    @"Bob Drury" said:
    Most recent revision see docx file examples updated
    Regards
    Bob (WRD)

    Great work Bob!

  • PublisonPublison Posts: 11,966

    @Maciek said:
    Valuable information inside. Thank you.
    May I suggest updating the first post with the newest doc file and commenting the changes within the consecutive posts ?
    This way one will always have the newest document version at the top and the newest comments detailing the changes as they come in the posts.

    +1

  • Maciek
    I will see if I can do that on the next update.
    Regards
    Bob (WRD)

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