Design overview advice needed

Discussion in 'Embedded Systems and Microcontrollers' started by swmcl, Jun 12, 2010.

  1. swmcl

    Thread Starter New Member

    Jun 12, 2010
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    Hi,

    I need to design a controller for a machine with these needs:

    - 3 temperature measurements (3 x A/Ds).
    - a heater / cooler control that is duty cycle controlled over a period of perhaps minutes (a PWM with a period of minutes).
    - a timer (count up or count down) showing time accurate to the second.
    - an RPM circuit for up to around 40 RPM and down to 5 RPM.
    - access to an EEPROM.

    I'm planning on using a PIC16F877A. I was also planning to use a 40 x 4 LCD display.

    Is this all possible on the one PIC ?

    I'd appreciate some discussion because I'm losing my mind with this one!

    Cheers,
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Is this a classroom assignment?

    hgmjr
     
  3. swmcl

    Thread Starter New Member

    Jun 12, 2010
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    No. I'm trying to build a bath in which I mix chemicals at different temperatures. It is not commercial either !

    Sorry if there was that impression.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    What is your budget for this design?

    hgmjr
     
  5. swmcl

    Thread Starter New Member

    Jun 12, 2010
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    I've purchased a few of the items already. I'm expecting to spend over $800 US on bits and pieces.

    Rgds,
     
  6. hgmjr

    Moderator

    Jan 28, 2005
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    Have you commited to PIC and if so have you already purchased the software development tools?

    hgmjr
     
  7. swmcl

    Thread Starter New Member

    Jun 12, 2010
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    I've built my own PIC programmer that uses the ic-prog program - hence the preference for the 877A. I've got another PIC / serial EEPROM programmer lined up for purchase. I am an analogue engineer and have a fairly comprehensive workshop out the back. I'm not experienced with PICs very much. I've built a couple of small projects in the past. My experience is in analogue electronics much more than in digital electronics.

    Rgds,
     
  8. hgmjr

    Moderator

    Jan 28, 2005
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    As an analog engineer myself, I can tell you that you are in for a treat with microcontrollers. I am an ATMEL AVR designer so I will have to leave you at this point since I know nothing about PICs.

    hgmjr
     
  9. swmcl

    Thread Starter New Member

    Jun 12, 2010
    6
    0
    Thanks!

    I'm not sure what 'treat' means ... at the moment it all looks too difficult. The code I've seen looks pretty challenging also.

    Cheers,
     
  10. hgmjr

    Moderator

    Jan 28, 2005
    9,030
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    By "treat", I mean that you will have a lot of fun learning and working with microcontrollers.

    hgmjr
     
  11. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    I would recommend using the pic18 series if C (C18 is pretty solid) is your programming language of choice or anything else for that matter. Better bang for the buck.
    http://ww1.microchip.com/downloads/en/devicedoc/39564c.pdf
     
  12. swmcl

    Thread Starter New Member

    Jun 12, 2010
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    Why the PIC 18 series? What feature in particular ?

    I have absolutely no experience with the 18 series I must admit.

    Rgds,
     
  13. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    Overall just a better design. More memory, faster access and advanced modules with less errata than the 16 series. (bugs in chips are still being fixed)

    I think you will have a good learning curve to get up to speed, if you start with the 18 series it might even be faster because of all effort microchip has put into 16 to 18 migration on the training sites.
     
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