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The LEDs on the MCBx51 board are:

  • The POWER LED indicates that power is present on the board.
  • P1.0 - P1.7 connect to eight Port 1 pins when DIP Switch 9 is ON, and may display program status while testing your applications. Setting the DIP Switch to OFF disables the LED drivers.


The Port 1 LEDs flash during reset and display the configuration status of the Monitor EPROM. When this DIP switch is OFF, the Monitor does not affect the Port 1 pins during the reset phase.

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