lecture23

lecture23 - FoundationsofEmbeddedSystems CTermSpring2008

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Foundations of Embedded Systems C Term Spring 2008 Lecture #23:  Interrupts and ISRs Reading for Today: User's Guide Ch 2, TI Mixed C language notes Reading for Next Class: Review all since Exam 2 HW #6 (on web):          Due Monday 10/13/08 in class (BONUS!) Lab #4 (on web): Report due NEXT Thursday 10/16/08  EXAM #3 – Tuesday 10/14/08 Last Class :   One more procedure/stack example(example code is posted) >>  Using the Hardware Multiplier   >>  3 ways to alter flow of program execution: jumps, procedure calls, interrupts.        >>  Interrupts are signals from peripherals requesting service from CPU.  >>  Sequence of Event when an NMI or Enabled Interrupt Occurs. .. 
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
>>  Sequence of Event when Returning from an Interrupt 
Background image of page 2
What if multiple interrupts occur? >> REMEMBER:   By default all interrupts are  disabled inside an ISR  because status register (SR) is cleared --> Programmer (i.e. YOU) must re-enable interrupts inside ISR for multiple interrupts to  be acknowledged.  Otherwise, additional interrupts are ignored while inside ISR >> RETI restores the SR and will re-enable interrupts automatically at end of ISR Example :     ; Inside main ... MOV @R7, R4 ; INT from ADC occurs      . .. ADC_isr ; ISR for A-to-D converter EINT ; re-enable interrupts inside ISR PUSH R6 PUSH R8 ; INT from TIMERB occurs and is serviced ... POP  R8
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/27/2008 for the course ECE 2801 taught by Professor Jarvis during the Fall '08 term at WPI.

Page1 / 8

lecture23 - FoundationsofEmbeddedSystems CTermSpring2008

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online