Experimental Design for Solar Auto Shutdown Controller

Discussion in 'The Projects Forum' started by patrickdel1982, Nov 29, 2009.

  1. patrickdel1982

    Thread Starter New Member

    Nov 29, 2009
    • My objective is to create a battery-operated counter-controller which shuts down an external function “X” via an analog signal after one cycle of thirty-two (32) days (e.g. 2764800 seconds) unless the counter-controller is “unlocked” through a security code is entered through a USB port to renew the count.
    • The unit should be able to display the number of days left in the counting cycle on a small LCD, starting from thirty-two (32) days and counting down to zero (0).
    • The external function is run through a PIC16F785, which has an available analog input. There should be a string of five (5) security codes stored on the counter-controller memory which repeat every five (5) cycles.
    • The counter-controller should be as low-power, running as few watts as possible. The system should also work on a 3.0-4.0 volt range (single lithium-ion battery).
    • The default mode for if the battery has low power below 3.0V is, “locked, but not counting,” meaning that the external device cannot function but the counter-controller stops counting for the time being until the battery is charged above 3.0V.
    • Since the unit is solar powered, the entire counting and controlling regime must be super low-power. There is a switch which a human user will push periodically (perhaps 3-20 times per day) to activate and deactivate the external function “X,” so a count check, date display and control function can be hypothetically performed only at these times.
    • As a side note, the USB port used to unlock the system should use its external 5V power source to charge the battery while unlocking.

    My experience with microcontrollers, counters and IC’s is limited, having a fair working knowledge of 8-bit MCUs, perhaps able to debug codes written in C format, but not a true designer or troubleshooter. Overall I am a beginner level with microcontrollers, but have a good working knowledge of circuit design. Can anyone give me a recommendation of where to start? I am interested in PIC microcontrollers, but not strictly limited if nothing fits the design parameters above.
    Here is a basic diagram of the functionality of the counter-controller:



    Can anyone offer any help with what PIC families and features I should look for? Are there any PICs which provide counting units? How much memory will I need? How can I find a PIC or incorporate a design that will fulfill all of the above requirements? What approach should I use on this design? Any ideas or tips?

    Thank you for your time.
  2. JDT

    Well-Known Member

    Feb 12, 2009
    For a USB controlled micro-controller project using the Atmel chip look at the Teensy Development Board:-


    But, it will be a steep learning curve!