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Key press to switch on uC, timer to switch off power control of uC ?

Discussion in 'Embedded' started by Martin Maurer, May 10, 2005.

  1. Hello,

    i want to use a uC for a remote control. I want to switch on the uC via a
    keypress, start the programm inside and switch the complete power off after
    a certain time (e.g. 30 seconds).

    I thought it could be done in the following way:
    Key press (it is coming from a 4 x 3 matrix keyboard) must enable delivering
    power to uC, the uC starts up and a output PIN also must enable delivering
    power (so the power remains when the key is released). After doing some
    tasks and getting idle, the output PIN for power control changes and the
    complete system is switched off.

    Can someone suggest how to implement the power part or point me to schematic
    for such a thing on the web ? Can i do it with 2 transistors ? Controlling
    the output port and writing the software afterwards is not a big problem,
    but i have no knowledge about analog circuits.


    Martin Maurer, May 10, 2005
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  2. Martin Maurer

    James Beck Guest

    Most MCU's have some sort of sleep or low power mode that draws in the
    microamp range, which is usually less current than the self discharge
    rate of most modern cells. It is a trivial matter to have say a PIC MCU
    go to sleep after a period of time and wake on a button press.

    James Beck, May 10, 2005
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