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Thread: External Hard Reset for 18m2

  1. #1
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    Default External Hard Reset for 18m2

    I need an external hard reset of the 18m2. Can I get advice on the how to do this?

    I have 08m external hard reset circiut and I am looking to for the same circuit (if possible) for the newer device.

    Thank you in anticipation.

    Anobium

  2. #2
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    There's no way to add a true external hard reset to an M2 PICAXE other than using a means to cut power and restore it.

    The 'reset' on leg 5 of earlier 18-pin PICAXE is just another input (C.5) on the 18M2. You can interrupt on it going low, poll it, and issue a RESET command when it goes low, even put that in a separate task, so it acts like a reset input, but that won't help if the PICAXE is in a blocking command.

    As you've got an external reset circuit for the 08M I'd have thought it would be the same for the 18M2. As you've already got it for the 08M I'm a little confused as to what you are asking for.
    Last edited by hippy; 26-03-2011 at 13:58.

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    I am looking for validation of the 08m approach (see attachment).

    Will this work for 18m2? which pyhsical pins to use? and, are there any dangers etc?
    Attached Images Attached Images

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    That circuit will work in most situations.

    However, it won't react while blocking commands have been issued - so use serin, infrain etc, and the reset will no things (in the same way that an interrupt on C.5 would do nothing).

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    @andrew. Thank you. Can I clarify? Where can I find a list of blocking commands? And_ may I ask you to review the last sentence. I cannot understand.

    Cheers

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    My last sentence was refering to what hippy said:

    The 'reset' on leg 5 of earlier 18-pin PICAXE is just another input (C.5) on the 18M2. You can interrupt on it going low, poll it, and issue a RESET command when it goes low, even put that in a separate task, so it acts like a reset input, but that won't help if the PICAXE is in a blocking command.

    In other words, your method would have the same limitations.

    I'm not aware of a list of blocking commands anywhere, but ones I can think of include:
    - rfin
    - serin
    - infrain
    - keyin

    Andrew

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    Some PAUSE, SLEEP and COUNT can block for significant amounts of time, and also SERRXD and DISCONNECT are permantly blocking ( until RECONNECT issued or power-cycled ).

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    A push to break switch on the power rail will also very simply do the job!
    PICAXE Technical Support

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    @Technical.

    I am using an AXE091 board and I require an 08m to trset the 18m. Currently I am connecting and reconnecting the power to all devices. So, I need to reset single devices not the whole board.

    I will try the 08m circuit and report back.

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