Suggestions for a MCU

Discussion in 'Embedded Systems and Microcontrollers' started by Dritech, Feb 19, 2016.

  1. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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    Hi all,

    I am doing a battery operated project and will be using an MCU to process 6 analog inputs,
    Can someone please suggest the best MCU for the following specs:
    * It should have at least 6 ADCs
    * Ideally it should be a low-power MCU since it will be battery powered
    * Small package size
    * I will be using a digital filter for filtering the 6 analog inputs

    I found the following two PIC MCUs but I'm not really sure if they are good for performing digital filtering on them:
    PIC16F688
    PIC16F1503

    Any suggestions would be highly appreciated.
     
  2. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    No 18F micros? There are some where you can sample two channels at a time.
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
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  4. NorthGuy

    Active Member

    Jun 28, 2014
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    If you want to go low power, you need to look at "LF" parts, e.g. PIC16LF1503 instead of PIC16F1503. The difference in power consumption is dramatic.

    Parts which have "1" after "F" are newer and generally better in every respect. PIC16LF1503 with 20nA sleep current is a good candidate.

    Power consumption depends a great deal of what you're doing. Running slower clocks or sleeping between your operations will let you save more power.
     
    boltspinner, JohnInTX and panic mode like this.
  5. JohnInTX

    Moderator

    Jun 26, 2012
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  6. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    Thanks for the replies.

    Is the PIC16LF1503 good for performing digital filtering? What parameters should I look for?
    This is my first attempt of implementing a digital filter of an MCU.
     
  7. Papabravo

    Expert

    Feb 24, 2006
    10,163
    1,796
    As you know the key operations in digital filtering are multiplication and addition. With an 8-bit datapath, you will be limited in the number of multiply/add cycles you can perform per second if you need more than 8 bits in your results. You should look at the dsPIC series of parts. They have other features which make life easier with FIR and IIR filtering.
     
  8. Electro nS

    New Member

    Feb 20, 2016
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    i would advise you to use dspic33ep series .
    1-They are low power (EP series)
    2-They contain multiple ADC for simultaneous sampling
    3-They contain DSP core which is very important for digital filter and digital signal processing algorithms
    4-They are fast (up to 70MIPS) and 16bit architecture
     
  9. dannyf

    Well-Known Member

    Sep 13, 2015
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    Low power is mostly a software thing: how you operate the mcu makes a lot of difference.

    The newer parts tend to be more powerful, with more features and less expensive.
     
  10. Picbuster

    Member

    Dec 2, 2013
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    Your question is simple however we need more information:
    density you want?
    Accuracy wanted?
    Signal speed?
    Signal form?
    Operating temperature (environmental)
    Communication with processing unit ( when, due to wanted spec's forced to be external from cpu)
     
  11. JohnInTX

    Moderator

    Jun 26, 2012
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    That's not true. Even the most cursory examination of the PIC datasheets will show that parts characterized for low power consume less than the compatible standard part. Obviously software is an important part as well but for low power applications, you start with a low power chip then go from there. Ref: PIC16(L)F1574 Electrical Characteristics.
     
    tracecom likes this.
  12. NorthGuy

    Active Member

    Jun 28, 2014
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    Depends on your speed. It doesn't have hardware multiplication, so you will not achieve high speeds with it.

    For high speed, look at dsPIC33 (there are FJ and EP series). It has hardware DSP engine so FIR filters or alike will be very fast, but it won't be low power by any means - thousands times more than PIC16LF1*.

    A compromise between these is PIC24F*K* series. They're low power (although not as low power as PIC16F1*), and they don't have DSP as dsPIC33, but they do have 16x16 hardware multiplication and implementing FIR is easy.
     
  13. dannyf

    Well-Known Member

    Sep 13, 2015
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    it depends on what kind of "digital filtering" you are talking about.
     
  14. Picbuster

    Member

    Dec 2, 2013
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    Agree with JonlnTX
    Software and hardware do the job for low power. Some of the hobbyists forget to look at a power supply quiescent current:
    a lm78 takes a huge 4 mA The mcp170x series 10 micro amp
    voltage divider to measure battery 90K and 10K in series @ 10V versus 900K and 100K in series. sure you have to add extra attention to the analogue internal input impedance. (300Kb approx. with a low capacitor for the hold circuit)
    MPU clock speed 10Mhz versus 32KHz.
     
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