Interrupt on any of 3 pins on PORTB, K60 under MQX

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Interrupt on any of 3 pins on PORTB, K60 under MQX

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kerose98
Contributor II

I have a project where I have 3 inputs into PORTB - I must be able to respond to an interrupt from any of these three pins.  In a previous version of the same project, we have the interrupts working just fine, but since then, MQX has changed to using LWGPIO which handles one pin at a time.  I need to write the ISR so that when the ISR is called, I can very quickly detect which pin was set to interrupt, and then I set the appropriate global variable to 1.  That's it.  I tried using the LWGPIO functions within the ISR, but that is too much latency.

A previous version of the same project, which was non-RTOS, used the Processor Expert to handle the interrupts and it did fine.  I need the RTOS due to the existence of Ethernet, USB, Bluetooth, and WiFi on the same system (along with an RS-232 port).  In all ways, the RTOS makes life easier.

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anthony_huereca
NXP Employee
NXP Employee

Hi Kevin,

  If I understand your problem, using the lwgpio code below in your ISR to check which pin was used and to clear it isn't fast enough?

  if(lwgpio_int_get_flag(&btn1))

  {

    lwgpio_int_clear_flag(&btn1); //Clear interrupt flag

    //do more stuff

  }

  Those lwgpio API calls are just modifying the PORTx_ISF register to read and clear, and should be very fast. If it's still too slow, you could setup a kernel ISR with _int_install_kernel_isr instead of using the normal _int_install_isr which has some RTOS overhead involved. There are some extra steps to use that, see this thread for some information on it: K60 and MQX installed ISR not called, why?

Also be aware that kernel ISRs cannot use any MQX features like starting a task, setting a semaphore, etc.

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anthony_huereca
NXP Employee
NXP Employee

Hi Kevin,

  If I understand your problem, using the lwgpio code below in your ISR to check which pin was used and to clear it isn't fast enough?

  if(lwgpio_int_get_flag(&btn1))

  {

    lwgpio_int_clear_flag(&btn1); //Clear interrupt flag

    //do more stuff

  }

  Those lwgpio API calls are just modifying the PORTx_ISF register to read and clear, and should be very fast. If it's still too slow, you could setup a kernel ISR with _int_install_kernel_isr instead of using the normal _int_install_isr which has some RTOS overhead involved. There are some extra steps to use that, see this thread for some information on it: K60 and MQX installed ISR not called, why?

Also be aware that kernel ISRs cannot use any MQX features like starting a task, setting a semaphore, etc.

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kerose98
Contributor II

I was using different code than what you have listed there, and I tried it and it does work correctly.  Now I have something else going on in the system now that I have solved the interrupt question.  Thanks!

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