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Propellor Multitask — Parallax Forums

Propellor Multitask

Scott2HotScott2Hot Posts: 10
edited 2009-02-22 01:00 in Propeller 1
I·do not·know much about the propellor but very interested in it. I have been playing around with the BS2 homework board and starting to get back my interest with the electronics hobby. I have been writing programs with the BS2 trying to integrate·it into my rc airplane. The problem with the BS2 is·controlling a servo and trying to do other tasks like·monitor I/O and timers·at the same time. I just ordered a whole bunch of components like the PWMPAL and the GPS module among other things to help. I have experience with PLC's and ladder logic programming.·PLC's are very expensive and impractical for what I want to do. Is it possible for the propellor to control·a servo and other functions like timers and counters·at the same time?

Comments

  • telluriantellurian Posts: 52
    edited 2009-02-20 23:57
    Yes it is possible to control several things at one time independently of each other. That is one of the key features of the propeller. It has 8 "cogs" or 8 processors each of which can be programmed to handle a different task.
  • Scott2HotScott2Hot Posts: 10
    edited 2009-02-21 00:32
    With the 8 cogs it seemed like that would be the answer. Thank you! There was a couple of different options to get started with the propellor. I have a good electronics background. I was thinking of purchasing the propellor propstick·USB education kit. Is this the best option to start experimenting with the prop? I would prefer to stay with the 5 volt signals.·Maybe I am just old school.
  • telluriantellurian Posts: 52
    edited 2009-02-21 01:02
    Scott2Hot said...
    With the 8 cogs it seemed like that would be the answer. Thank you! There was a couple of different options to get started with the propellor. I have a good electronics background. I was thinking of purchasing the propellor propstick USB education kit. Is this the best option to start experimenting with the prop? I would prefer to stay with the 5 volt signals. Maybe I am just old school.

    Well, the Prop is 3.3v based and needs interfacing glue for 5v signals but this is usually easily solved with a 1K or 2K resistor in series with the 5V signal in (but not always, it depends on the bandwidth you need, at very high frequencies the resistor approach will not work). Check the Propeller Hardware stickies at the top of the forum page for info.

    The USB stick version is good but it can only source a few ma for external circuitry from its voltage regulator. I'd go with the 40 pin version, it includes a Prop Clip for USB interface. You can the use this for other projects too.
  • JasonDorieJasonDorie Posts: 1,930
    edited 2009-02-21 02:59
    For a quick start, a ProtoBoard and a PropPlug is cheaper than the PropStick USB, and you'll re-use the PropPlug. The regulators on the ProtoBoard will source more power, provide both 5V and 3.3V, and you can easily mount header pins around the Prop to make it simple to connect to a breadboard via jumpers. It also has optional parts available to connect a mouse and VGA display which is incredibly helpful for debugging.

    On the other hand, the PropStick USB is pretty nice (I have two) and works just fine if you don't need it to source much externally.

    You can also use the USB connection on either the PropStick USB or the ProtoBoard for debugging also - It just shows up as a standard serial port, and the Prop comes with nice libraries for serial communication, printing numeric values, strings, characters, etc.

    Jason
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-21 07:32
    If you have a couple weeks to wait I am building a development board designed to be used in end products. Comes with 1A switching power supply, 512kbit eeprom, and rtc all in a wide dip 40 package(2"x0.8"). Prototype will should be done monday so assuming I made no mistakes i can start manufacturing in a week.
  • Mike HuseltonMike Huselton Posts: 746
    edited 2009-02-21 07:42
    mctrivia,

    A one amp switching supply? Are you looking for trouble - RF noise, spikes, etc? Please consider carefully what you are planning.

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    JMH
  • mctriviamctrivia Posts: 3,772
    edited 2009-02-21 07:58
    i wanted switching for battery operated device life. Voltage input to this module is 2 to 14V and 98% efficient conversion. Depending on how my tests go I may be bumping the voltage up a little and running a linear regulator in series. my pcb layout was carefully layed out to minimize rf from switching to the rest of the module. I also layed it out so the on board regulator does not need to be used if you are very sensitive to noise you can directly power it from any 3.3V power source.

    My thinking for this module. Small, code security, work as end product and development platform. Great pains have been taken to keep it only slightly larger then the 40pin dip prop pins to line up with a bread board, and make it so that if used for end product no one can download or alter your code.
  • Mike HuseltonMike Huselton Posts: 746
    edited 2009-02-21 08:02
    Alright.

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    JMH
  • LeonLeon Posts: 7,620
    edited 2009-02-21 12:04
    Switching regulators are commonly used for powering processors and FPGAs - it's the only way to get voltages like 1.0V at 1A or more that are often required these days.

    Leon

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  • mctriviamctrivia Posts: 3,772
    edited 2009-02-21 23:03
    the only problem with the switchng supply is it is not cheap. Estimate costs for this module are:

    $50CAN for main module(prop, eeprom, crystal, data protection system
    $10CAN for real time clock(clock, crystal, lythium battery)
    $17CAN for power supply.

    Exchange rate right now is about 1.22 right now so module is about $40US
    The power supply can be left unpopulated when shipped so you can solder on the parts your self if you need them later. The RTC though because of the safety features must be put on at time of manufacturer if you want it(though I can leave off the battery and crystal saving you $5)

    If populated the switching supply can run your project and the module.
  • Scott2HotScott2Hot Posts: 10
    edited 2009-02-22 01:00
    I just looked up the Propellor Protoboard USB. There is also the Propellor Protoboard which is 10 dollars cheaper than the USB version but requires the Prop Plug to program it. The Prop Plug can also be used to program the Prop Stick and would be the most economical solution in the long run. It looks like a good start with the propellor and can do much more than the BS2 for less money. Thanks for all the information!
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