recommend a PIC

Discussion in 'General Electronics Chat' started by Coollestersmooth, Dec 30, 2014.

  1. Coollestersmooth

    Thread Starter Member

    Dec 18, 2014
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    Can anyone recommend me a PIC for performing 4 bit logic, capable of a minimum of 20 functions (AND, OR , NOT) for a BCD to 7 segment display decoder driver?
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    All PICs can do these things.
     
  3. Brevor

    Active Member

    Apr 9, 2011
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    The first step in selecting a PIC is you need to determine the number of inputs and outputs you will need.
     
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  4. Coollestersmooth

    Thread Starter Member

    Dec 18, 2014
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    4 inputs, 7 outputs.

    is this input capture/output compare on a datasheet?
     
  5. ian field

    Distinguished Member

    Oct 27, 2012
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    Your biggest concern might be - does it have enough pins?
     
  6. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    No, inputs and outputs are just that; inputs and outputs. Capture and compare are special functions within the PIC.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Input and outputs are a good starting point. Next comes voltage range as some of the newer devices only work in the 3.3V range when you really wanted 5V.

    I would limit to devices with an internal oscillator even if a crystal will be used. It just makes initial hardware debugging easier.

    Aditionally, a PIC is not a logic device where inputs "flow" to outputs. Inputs must be read, computations computed, and output pins set in a sequential program. While the given function (read 4 bits, set 7 bits) can be performed in a very short sequence of instructions those instructions must be there, and there will be a lag between input change and output response.

    If this is your first project seriously consider getting a development board along with a PICkit, and if you get one from Microchip you can get some tutorials too.
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    a good starter pic is 16F690, internal oscillator, no xtal reqd,
     
  9. takao21203

    Distinguished Member

    Apr 28, 2012
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    PICs are not difficult to get along with, all you need is a PICKIT3.

    I used the 16F884 a while ago, it doesnt have large memory, but can do simple tasks such as 7segment.

    You can get them as PDIP40 too. You really only need 4 connections: DAT/CLK - 2 wires for programming. MCLR - the programming voltage. GND - a common ground.

    If you have some RF coils they are happy with 22uH to 100uH no extra parts, no crystal.

    A small capacitor. Thats really it!

    Get MPLABX free download. It can generate all the C and H files as a project.

    No need to dive into assembler tutorials. Just read the datasheet carefully, and treat the PIC that way.
    OK you need some hints if you never used embedded C.

    Maybe try the new PICs which can work with the CODE CONFIGURATOR. Its even easier.
     
  10. Brevor

    Active Member

    Apr 9, 2011
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    I would suggest you look at the 16F818, it has 16 IO lines configured as 2 8 bit ports. That will make the programming easier as one port could be used for your outputs and the other for the inputs. You would also have a few extra input lines available if you wanted to add some features like a blanking input that would turn off all the outputs, or a lamp test input to turn all the outputs on to test the display. You could also use an input to be tied high or low to tell the PIC if it should sink or source current on the outputs.
     
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