Hi,
I want to add a function handling nested interrupts for the controller. Could you tell me the right position to add this function?
startup-file:
Undef_Handler B Undef_Handler SWI_Handler B SWI_Handler PAbt_Handler B PAbt_Handler DAbt_Handler B DAbt_Handler ;IRQ_Handler B IRQ_Handler IRQ_Handler B irq_fnct FIQ_Handler B FIQ_Handler irq_fnct //do some stuff - nested interrupt
I've add one breakpoint to the irq_fnct but it seems that the programm will not reach this part if a interupt occur.
I'm working with the atmel controller AT91SAM7S.
best regards Peter
Even if interrupts occur at nearly the same time, it is the job of the VIC to arbitrate. Are you working on a trully time-critical application? I'm currently working on a product that has an Ethernet connection, a USB connection, a continuously employed UART, a hardware timer generating interrupts and an LCD controller. all these are serviced well and concurrently without nested interrupts.
How did you organized your different interrupts? Do you work without an operating system?
The current project I'm working on has also ethernet, uart, an tft with touch, as well as user inputs (buttons) - without any kind of O/S.
Of course you can adjust stack sizes, but that consumes RAM that you might need for something else. That's right... but most of the code is executed in sdram and the stack is located in the internal sram.
I happen to work with RTX, but an RTOS should not be a factor in the decision to use/avoid nested interrupts. some of my tasks wait for signals from interrupts, to do some later, heavy processing. In the end, you want to build a stable system. As Per mentioned, you cannot do that if you run risk of running out of stack space. Keep your interrupt service routines short. do heavier processing in your main loop (don't forget synchronization issues). if you work efficiently, that should suffice.