Texas Instruments MSP430

Interrupts, The Big Picture
Chapter Topics
Interrupts ..................................................................................................................................... 5-1
Interrupts, The Big Picture ........................................................................................................ 5-3
Polling vs Interrupts ............................................................................................................... 5-3
Processor States and Interrupts ........................................................................................... 5-5
Threads: Foreground and Background ................................................................................. 5-6
How Interrupts Work ................................................................................................................. 5-7
1. Interrupt Must Occur ......................................................................................................... 5-9
2. Interrupt is Flagged (and must be Enabled).................................................................... 5-10
3. CPU's Hardware Response ............................................................................................ 5-12
4. Your Software ISR .......................................................................................................... 5-14
Interrupts: Priorities & Vectors ............................................................................................... 5-17
Interrupts and Priorities ....................................................................................................... 5-17
Interrupt Vector (IV) Registers ............................................................................................ 5-18
Interrupt Vector Table ......................................................................................................... 5-19
Coding Interrupts ..................................................................................................................... 5-22
Dedicated ISR (Interrupt Service Routine) .......................................................................... 5-22
Grouped ISR (Interrupt Service Routine) ............................................................................ 5-24
Enabling Interrupts .............................................................................................................. 5-26
Miscellaneous Topics .............................................................................................................. 5-28
Handling Unused Interrupts ................................................................................................ 5-28
Interrupt Service Routines – Coding Suggestions .............................................................. 5-29
GPIO Interrupt Summary .................................................................................................... 5-30
Interrupt Processing Flow ................................................................................................... 5-30
Interrupts and TI-RTOS Scheduling ........................................................................................ 5-31
Threads – Foreground and Background ............................................................................. 5-31
TI-RTOS Thread Types ....................................................................................................... 5-33
Summary: TI-RTOS Kernel ................................................................................................. 5-36
Lab Exercise ........................................................................................................................... 5-37
5 - 2 MSP430 Workshop - Interrupts