PIC16F1503 Fixed Voltage Reference


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    Junior Member AussieBarry's Avatar
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    Default PIC16F1503 Fixed Voltage Reference

    Hi All,

    I am working with a PIC16F1503 and would like to use the Fixed Voltage Reference (FVR) as the reference for the ADC.
    I have successfully done this in the past using a PIC16F1829 but the same register settings do not apply for the PIC16F1503.

    In the case of the '1829:
    From the datasheet, setting ADPREF<1:0> to "11" means "Vref+ is connected to internal Fixed Voltage Reference (FVR) module

    In the case of the '1503:
    From the datasheet, the only two setting options for ADPREF<1:0> are "00" (Vrpos is connected to Vdd) and "10" (Vrpos is connected to external Vref+ pin)
    All other options are "Reserved" and there is not FVR option listed.

    Can anyone enlighten me on how to use the Fixed Voltage Reference (FVR) as the reference for the ADC on a PIC16F1503?

    Cheers
    Barry
    VK2XBP

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    Senior Member Henk57's Avatar
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    Default Re: PIC16F1503 Fixed Voltage Reference

    Barry.

    Chapter 13.3 page 110, you will find the FVRCON Register.

    Henk.

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    Prolific Poster rcurl's Avatar
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    Default Re: PIC16F1503 Fixed Voltage Reference

    Hi Barry-
    It looks to me like the wizards at Microchip have done something really strange here. The way I read the spec sheet for the 16F1503, the Fixed Voltage Reference cannot be used as the reference voltage input to the ADC BUT it can be used as one of the input channels to the ADC so you can compare the analog voltage you are reading against the voltage from the reference. Look at the figure on page 113 of the spec sheet. To send the FVR to the ADC INPUT, set bits 6-2 of ADCON0 to 11111.

    Yep- it would have been WAY too simple if they had implemented the FVR the same way on all of their devices........

    -Rick
    KM4NDI

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    Prolific Poster charliecoultas's Avatar
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    Default Re: PIC16F1503 Fixed Voltage Reference

    Barry

    Completely off-topic, I love your shiny brown coat. How did you achieve such a glossy finish?

    Charlie

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    Fanatical Contributor Les's Avatar
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    Default Re: PIC16F1503 Fixed Voltage Reference

    I'm having this problem with all the new devices that Microchip are bringing out Rick.

    They are changing things in the device, for no real reason, that have been the same for many years, and worked perfectly for many years. Yet, they do not inform any one of the changes! A simple pdf file for each new device and each peripheral to indicate what is different for the same peripherals, is all that is required.

    They seem to have a new breed of nerd in Microchip, but the nerds don't actually seem to use the devices themselves, otherwise, they would not see the need in changing things that don't need changing. Unfortunately, that's what happens when university graduates are brought in, or Drs, or Professors etc.. All theory, but no actual practical usage!

    I've seen it so many times over the years in different industries, and I've actually worked with people who go from A to Z, then round again, just to get to D, when all they had to do was use common sense and go from A to D directly. But this isn't what was taught to them, and they don't actually know the electronic item, or microcontroller, or software enough to make a common sense judgement! Then complain that, "that's not the way to do it" when the correct path is given to them and the device works perfectly with it.

    We had one guy when I worked for Sky, repairing the satellites, that would take all morning making measurements of a faulty unit, and ignore what I was saying to "look at that device because it will be faulty, and replacing it will fix it", because he had a university diploma, but I didn't, so I must be wrong. Even though I had been working in the electronics industry since I was a kid! Then would find the item that I said would be faulty was the problem! But it never stopped him, and he did the same everyday for 7 years. It's just a good job we weren't on piece work, otherwise he would have been sacked, but we, stupidly, covered for the slow, or clueless, guys in the room!

    The same type of scenario seems to be creeping into the semiconductor industry, and the practical, common sense, guys don't actually exist anymore!
    Last edited by Les; 24th February 2018 at 13:31.
    For more example programs for Proton and Proton24 or updates, please visit: Proton WIKI or Proton Files

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    Junior Member AussieBarry's Avatar
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    Default Re: PIC16F1503 Fixed Voltage Reference

    Hi Charlie,

    That is a photo of my boy Australian Champion Fireax Twice The Valour ET WAC.
    His great coat was attributed to two main things - genetics and diet.
    His genetics are from the great breeding regime of Ella Pieton from Fireax Dobermanns.
    Valour was fed a raw, natural diet from the time he was born.
    He was my best mate and sadly missed - he passed away a few years ago

    Cheers
    Barry
    VK2XBP

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    Prolific Poster charliecoultas's Avatar
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    Default Re: PIC16F1503 Fixed Voltage Reference

  8. A fine looking dog. I'm sure you miss him. I had a Golden Retriever called Paddy for 14.5 years. He died in 2001 and I still miss him.

    Best
    Charlie

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