Hard Fault when disabling GPIO pin with interrupt configuration

geoffs — Wed, 08 Feb 2017 06:35:19 GMT

I have an application where I wanted to initially configure a pin as a GPIO input, with an interrupt triggered on a falling edge, and then re-mux the pin to an alternative function. It has been causing hard faults which I couldn't understand, so I have managed to recreate the issue with a very basic program on a FRDM-KL26Z board.

See below code snippet which sets up Port A pin 13 as a GPIO input, configures it to generate an interrupt on a falling edge, enables interrupts for Port A, then attempts to re-mux the pin to disabled state. A hard fault occurs at this point in the program.

CLOCK_EnableClock(kCLOCK_PortA);
PORT_SetPinMux(PORTA, 13U, kPORT_MuxAsGpio);
PORT_SetPinInterruptConfig(PORTA, 13U, kPORT_InterruptFallingEdge);
EnableIRQ(PORTA_IRQn); // this enable IRQ on all of Port A
PORT_SetPinMux(PORTA, 13U, kPORT_PinDisabledOrAnalog);

The code uses KSDK v2 commands for clarity, but the same fault occurs if the SDK function calls are replaced with the equivalent register read/write commands.

In the example above, the final re-mux was to disable the GPIO pin, but a hard fault occurs if it is re-muxed to other functions (Alt2, Alt3 etc).

Is anyone else able to replicate this behaviour ? Is this expected behaviour ? I haven't seen anything to suggest it is, but perhaps there is something buried in the ARM reference manuals which says not to change pin muxes when a pin is configured with interrupts.

If it is expected behaviour: what are the other options for either disabling or re-configuring the GPIO pin for alternative functions ??

Re: Hard Fault when disabling GPIO pin with interrupt configuration

kerryzhou — Thu, 09 Feb 2017 09:22:38 GMT

Hi Geoff Sokoll,

Did you add the port interrupt service function(IRQ function)?

If you didn't add it, when the interrupt happens, the code will enter in the hardfault.

So, please add the interrupt service function, then try it again.

Wish it helps you!

Have a great day,
Kerry

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Hard Fault when disabling GPIO pin with interrupt configuration

Re: Hard Fault when disabling GPIO pin with interrupt configuration