tut-ch6-solutions.pdf - 300044 Microcontrollers PLCs(Microcontrollers Solutions to Tutorial Questions \u2013 week 14 Review Problems Chapter 6 1 When

tut-ch6-solutions.pdf - 300044 Microcontrollers...

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1 300044 Microcontrollers & PLCs (Microcontrollers) Solutions to Tutorial Questions – week 14 Review Problems - Chapter 6 1. When interrupts are enabled on RB4to RB7, is it possible to use some of these pins as outputs or are they fixed as inputs as soon as the GIE bit is set in the INTCONregister? Solution: The purpsoe of an interrupt is fast response, an interrupt service routine is called, then the program returns where it was. Changing the input to an output and doing other things with it could mean you will miss another interrupt. Not to mention the need to "separate" electrically the input from the output on that same pin. 2. Explain the difference between returnand retfie. What problem will happen if they are not used in a subroutine call or interrupt call? Solution: The retfieinstruction sets the GIE bit. The returninstruction does not set the GIE bit. Both pop up return addresses to resume the execution of the suspended main program.
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