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Help about El Cheapo PICmicro Programmer

Discussion in 'Electronic Basics' started by Jack// ani, Jan 31, 2005.

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  1. Jack// ani

    Jack// ani Guest

    Hi all,

    I'm using El Cheapo PICmicro Programmer by Mike Predko's for learning
    uC. I don't know whether the software work in WindowsXP or not?? But
    while programming I get error: Programming Failure at Address 0x00,
    0x02805 was written, but 0x03fff was Read Back. And when I try to
    verify I get, PICmicro MCU does not have Correct Instruction at Address
    0x00, 0x02805 was expected, but 0x03fff is the actual. What could be
    the problem? Is this hardware problem or operating system problem?
    Any help is highly appreciated.

    Thanks a lot.
     
  2. Mark Jones

    Mark Jones Guest


    Hi Jack. Does this require your chip to have a bootloader already downloaded
    onto it?

    "3FFF" is equivalent to "not programmed" so what it's saying is, if the chip is
    supposed to have data there, it is either blank or not being programmed.

    Make sure the PIC's MCLR pin is being driven to +13v during the programming
    cycle. Also MCLR should have a 33k pullup resistor to Vcc. Hope that helps.


    -- "We cannot expect to stumble into happiness; it must come from within." MCJ
    20050119
     
  3. Mark Jones

    Mark Jones Guest

    Ooops, by Vcc I meant Vdd. Connect MCLR --> 33k --> +5v, not +13.
     
  4. Jack// ani

    Jack// ani Guest

    Hi Mark,

    Thanks for reply. I'm a newbie I don't know what do you mean by
    bootloader? Please tell me what it is? Please see the schematic here
    http://www.myke.com/elcheapo.htm, it is having no pullup resistor, so
    do I really need it, as you said? There is one more doubt regarding the
    schematic, I hope you will clarify it, is pin9 and pin10 of 74LS05
    connected to the same pullup resistor(R7) or not?

    Thanks again.
     
  5. Mark Jones

    Mark Jones Guest

    Aah okay. A bootloader is a program that is programmed onto a PIC so that it
    can be re-programmed (arguably) much easier, using a different method and
    without the need for +13v. Myke's schematic is for a regular programmer, which
    is what you need.

    Indeed, that schematic does not show a pullup resistor on MCLR. Let me explain
    what MCLR is used for. When this pin is at +5v, the PIC operates normally. When
    it is at 0v, this resets the PIC. When it is at +13v, the PIC goes into
    programming mode. But in this design there is no pullup resistor. It should work
    [here] just fine without it, but if you have problems try putting a 33k pullup
    from MCLR to what is labeled as Vcc (+5v.)

    As for operating the PIC after it is programmed, obviously for it to work in
    your target circuit the MCLR pin has to have the 33k pullup to +5v. Connecting a
    pushbutton switch from MCLR to GND makes a nice reset button. I recommend a
    0.01uF cap across the switch also, to help smooth out any voltage spikes.

    Good Luck.
     
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