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MELABS U2 - Programing 16F1825 in LVP mode using ICSP

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  • MELABS U2 - Programing 16F1825 in LVP mode using ICSP

    Hi guys , can you confirm that the beta version 4.50 can program the 16F1825 using ICSP in the LVP enable mode , I have not tried this yet but wish to , but are concerned the programmer has not taken into account the current ERRATA note for LVP for this chip - please see following and confirm !!!
    .

    The current ERRATA notes for the 16F1825chip advise the following

    4. Module: In-Circuit Serial Programming™
    (ICSP™)
    4.1 Bulk Erase Feature not available with Low-
    Voltage Programming mode
    A bulk erase of the program Flash memory or data
    memory cannot be executed in Low-Voltage
    Programming mode.
    Work around
    Method 1: If ICSP Low-Voltage Programming
    mode is required, use row
    erases to erase the program
    memory, as described in the Program/
    Verify mode section of the
    Programming Specification. Data
    memory must be over-written
    with the desired values.
    Method 2: Use ICSP High-Voltage Programming
    mode if a bulk erase is
    required.
    Affected Silicon Revisions - A0

  • #2
    The U2 programmer will always use the "High Voltage Programming" mode on those chips (9V Vpp).
    So that issue doesn't come into play.

    High voltage programming is always available, even if you enable LVP in the configs.

    However, if it were necessary to use "Row Erase" instead of "Bulk Erase", you could go to Options > More options and check the "Low Voltage erase".
    PBP3 Manual : Microchip Datasheets - 10F, 12F, 16F, 18F
    Never download a PIC datasheet from anywhere but microchip.com

    Comment


    • #3
      was looking at issues relating to the voltage and isolation as the pin is likly to be used / linked as I/O to TTL device. having 9v appear at its input may not be nice and programming in LVP , where the voltage is never higher than 5v would be good.

      I was looking at putting a resistor(10k) in series with the Vpp/Mrcr pin to the TTL device , but not sure how the TTL device would like 9v appear on it ,

      As this pin is both in and out H/L to the device i cant isolate with a diode

      Am i getting this right as this is first i tried with MELABS U2 , ICSP and the chip 16f1825

      Also if the VPP/Mclr pin is not connected to anything else but the ICSP header , can the WPU just be enabled on the pin and not require an external pullup ?



      cheers

      sheldon

      Comment


      • #4
        When the MCLR/Vpp/RA3 pin of an 1825 is not configured for "Master CLear Reset" ... it is INPUT ONLY.
        You cannot use it for output.

        When it is configured for MCLR, it automatically has an internal weak pull-up and does not require an external resistor.
        PBP3 Manual : Microchip Datasheets - 10F, 12F, 16F, 18F
        Never download a PIC datasheet from anywhere but microchip.com

        Comment


        • #5
          thanks darrel cheers

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