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Multiple microprocessor single power supply system shutdown

  • US 5,151,855 A
  • Filed: 10/19/1989
  • Issued: 09/29/1992
  • Est. Priority Date: 10/19/1989
  • Status: Expired due to Term
First Claim
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1. A power shutdown method for a system having a master microprocessor, a slave microprocessor having an analog-to-digital converter, and a single supply voltage source for the master and slave microprocessors, the master and the slave microprocessors communicating via a communication link therebetween, the method comprising the steps of:

  • sensing a power shutdown condition by the master microprocessor;

    sending a shutdown command from the master microprocessor through the communication link to the slave microprocessor to initiate slave shutdown procedures including storing variables to memory when a shutdown condition is sensed by the master microprocessor;

    powering down the system including the voltage source by the master microprocessor after a predetermined minimum time period after sending a shutdown command to the slave microprocessor, the minimum time period having a predetermined value that allows the slave microprocessor to complete the slave shutdown procedures;

    sensing a failed condition of the communication link by the slave microprocessor;

    sensing the power shutdown condition by the slave microprocessor analog-to-digital converter;

    sensing a failed condition of the slave microprocessor analog-to-digital converter by the slave microprocessor;

    executing shutdown procedures by the slave microprocessor (A) in response to a shutdown command received from the master microprocessor of (B) when the failed condition of the communication link is sensed by the slave microprocessor and the power shutdown condition is sensed by the slave microprocessor; and

    bypassing the shutdown procedures by the slave microprocessor when (A) the failed condition of the communication link is sensed by the slave microprocessor and (B) the failed condition of the analog-to-digital converter is sensed by the slave microprocessor.

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