Question

a-Are internal interrupts peripheral interrupts? Explain and give examples in regardstothe PIC16F877A microcontroller.
b-If the GIE bit (Global Interrupt Enable) is not activated, can we still enable aninterrupt, and have it function properly? Explain.
c-Is there a restriction on the initialization value of the TMR0 register? Explain.

Answer 1

A) Micro controllers are providing external and internal interrupts. Internal interrupts are occuring inside the microcontroller for performing a particular task.Examples for these types of interrupts are Timer interrupts(Timer0 and Timer1) ,A/D converter interrupts etc.In the case of these type of interrupts ,it is triggered by software.For example, timer interrupts are triggered by a software to complete the timer operation.Similarly in the case of A/D converter for completing analog to digital conversion one interrupt can be triggered. But in the case of external interrupts it is triggered by user.

B) There are various flags in INTCON Register like peripheral interrupt enable,external interrupt enable etc.Individual interrupts can be enabled or disabled through the individual enable bits in the INTCON register.

C ) Timer0 has software programmed clock source.It can be initialized through internal(timer mode) or external (counter mode)clock source.