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CX51: Filling Unused Interrupt Vectors with SJMP $

Information in this article applies to:

  • Cx51 All Versions


I need to certify my application, and one of the requirements is that I must fill unused interrupt vectors with an SJMP $ instruction.

How can I do this?


Add a small assembler module to your application that defines absolute segments for each unused interrupt vector location. For example:

          CSEG AT 0x0013  ; external interrupt 1
          SJMP   $

          CSEG AT 0x001B  ; timer 1 interrupt
          SJMP   $

          CSEG AT 0x0023  ; UART interrupt
          SJMP   $

          CSEG AT 0x002B  ; timer 2 interrupt
          SJMP   $



Last Reviewed: Thursday, February 25, 2021

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