PicBasic Pro 16F628A Clock speed help !


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  1. #1
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    Default PicBasic Pro 16F628A Clock speed help !

    Hi All

    Using PBP 2.50C

    Confused..... I am attempting to slow a 16F628A from the default 4Megs to 48K Clock Speed

    Am I right in assuming the Command :-

    PCON.3 = 0

    At beginning of code should do it....

    My code works fine at 4Megs and is not that complex... :-) Just drives a LCD and a few buttons.

    Any help welcome

  2. #2
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    Default Re: PicBasic Pro 16F628A Clock speed help !

    Hi Andy,

    The 16F628A does not have a frequency multiplier; you can either use the internal osc at 4 Mhz, or an external crystal upto a maximum of 20 Mhz.

    Regards,

    Anand

    Oops, sorry read the 48 Khz as MHz
    Last edited by ardhuru; - 14th April 2014 at 17:13.

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    Hi,
    Yes, as far as I can see setting PCON.3=0 should switch from 4Mhz (default) to 48kHz.
    However, PBP doesn't have a suitable DEFINE OSC xx for that frequency so all software timed commands will be off by a factor of about 83 (if you're using the default DEFINE OSC 4), ie a PAUSE 10 will in reality be a PAUSE 830 and so on. This affects ALL selftimed commands, like PULSIN/OUT, SERIN/OUT, LCDOUT, PAUSE, PAUSEUS, PWM and so on.

    For LCDOUT perhaps you could try changing your data and command delays by a factor of ~80 and see what happens. I'm not saying it'll work but it's worth a try. If you have any PAUSE or PAUSEUS in your code then you'd need to scale those too obviously.

    /Henrik.

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    I'm curious why you would want to slow the PIC to 48 kHz. What requirement prevents you from running at 4 MHz?

    It might be easier to run everything at 4 MHz and tweak whatever specific logic you want to simulate 48 kHz.

    Robert

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    Battery conservation, perhaps?

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    Yes…. Am attempting to use a pic in field from solar sources… so saving power is a premium !!!

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    Quote Originally Posted by andybarrett1 View Post
    Yes…. Am attempting to use a pic in field from solar sources… so saving power is a premium !!!
    This is from the datasheet

    Standby Current:
    - 100 nA @ 2.0V, typical

    • Operating Current:
    - 12μA @ 32 kHz, 2.0V, typical
    - 120μA @ 1 MHz, 2.0V, typical
    You can put the chip in standby mode and wake the chip up when needed using interrupts.

    Robert
    "No one is completely worthless. They can always serve as a bad example."

    Anonymous

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    Quote Originally Posted by rsocor01 View Post
    This is from the datasheet



    You can put the chip in standby mode and wake the chip up when needed using interrupts.

    Robert
    I Never thought of interrupts.... Even Better!!!

    Thank you

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    In Short ….

    It should work,,,?

    I understand Pause etc will be somewhat slower !

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    Default Re: PicBasic Pro 16F628A Clock speed help !

    Thank you all for help !

    BR
    Andy

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