PBP and 18F2550


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    Default Re: PBP and 18F2550

    Quote Originally Posted by chrisshortys View Post
    ...Are there many benifits to using the internal ones?...
    Fewer parts, lower cost, less chance of solder problems, less space required on PCB, saving the planet, the list goes on. I've been using external oscillatorsmainly 'cause I bought a bag and enough capacitors, but that might change with USB.


    Quote Originally Posted by chrisshortys View Post
    ..
    With the fuses what kind of thing am I looking for or do you know of a beginners guide, as I haven't really dealt with those bits yet!

    Thanks!

    The datasheet is your friend:
    http://ww1.microchip.com/downloads/e...Doc/39632e.pdf

    Page 32, section 2-3:
    When these devices are used for USB connectivity,
    they must have either a 6 MHz or 48 MHz clock for
    USB operation, depending on whether Low-Speed or
    Full-Speed mode is being used. This may require some
    forethought in selecting an oscillator frequency and
    programming the device.
    The full range of possible oscillator configurations
    compatible with USB operation is shown in Table 2-3.

    I just pulled out a 18F4550 about 10 minutes ago to get back into USB programming. We share the same datasheet, but I can't comment on config yet, I have to search the forum for examples first. (Here's an interesting thread to start with)
    http://www.picbasic.co.uk/forum/show...18f4550+config

    Robert



    EDIT: But then it says this under the table:

    Legend: All clock frequencies, except 24 MHz, are exclusively associated with full-speed USB operation (USB clock of 48 MHz).
    Bold is used to highlight clock selections that are compatible with low-speed USB operation (system clock of 24 MHz,
    USB clock of 6 MHz).
    Since several of my PCs don't have USB 2.0, I'll be targetting low speed.

    Oh yes, don't forget that new PCs have USB 3.0, you'll have to look at an expert here to know how to handle that.
    Last edited by Demon; - 10th January 2012 at 03:59.

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