examples/buttons: Fix poll mode for button press detection. by nishantifx · Pull Request #1 · linumiz/nuttx-apps

nishantifx · 2025-12-11T10:02:46Z

Summary

Fix the buttons example application to properly support both poll and signal modes for button press detection.
The existing implementation had issues with poll mode not correctly handling button press/release events and error conditions.
Refactored button state processing into a dedicated function and fixed error handling in both modes.
This change affects the buttons example application in nuttx-apps.
Related NuttX Apps : [BUG] Button daemon: Button status doesn't get detected when Polling is enabled #2

Impact

Is new feature added? Is existing feature changed? YES - Existing buttons example is fixed and refactored to work properly in both poll and signal modes.
Impact on user (will user need to adapt to change)? NO - Users can continue using the example as before, but it will now work correctly.
Impact on build (will build process change)? NO.
Impact on hardware (will arch(s) / board(s) / driver(s) change)? NO - Only the example application is changed.
Impact on documentation (is update required / provided)? NO - The example usage remains the same.
Impact on security (any sort of implications)? NO.
Impact on compatibility (backward/forward/interoperability)? NO - Fully backward compatible.

Testing

I confirm that changes are verified on local setup and works as intended:

Build Host(s): WSL (Ubuntu 24.04), x86_64, GCC 13.3.0
Target(s): tricore (tc397:buttons), arm (STM32F4Discovery:buttons)
Testing: Verified button press and release detection in both CONFIG_EXAMPLES_BUTTONS_POLL and CONFIG_EXAMPLES_BUTTONS_SIGNAL modes on both target boards

parthitce

Thanks for your efforts @Nishant-IFX

parthitce · 2025-12-18T07:26:20Z

examples/buttons/buttons_main.c

 #include <errno.h>
 #include <unistd.h>
+#include <signal.h>
+#include <inttypes.h>


nit, alpha sort

parthitce · 2025-12-18T07:26:43Z

examples/buttons/buttons_main.c

+static void process_sample(btn_buttonset_t sample,
+                           btn_buttonset_t *oldsample)
+{
+  int i;


move under CONFIG_EXAMPLES_BUTTONS_NAMES

parthitce · 2025-12-18T07:27:50Z

examples/buttons/buttons_main.c

+      /* Initialize the set to empty, then add the configured button
+       * signal.
+       */
+


nit, remove empty lines. applies everywhere

nishantifx · 2026-01-02T05:45:21Z

Addressed all review comments and updated accordingly. Please review and let me know if any further changes are required.

sivaifx · 2026-01-05T08:47:20Z

examples/buttons/buttons_main.c

        }

      sample = (btn_buttonset_t)value.si_value.sival_int;
+      process_sample(sample, &oldsample);


CONFIG_EXAMPLES_BUTTONS_NAMES is optional config. If this config is not enabled, then you will run into compilation issues. Ensure, process_sample is called, only when the config is enabled, else print the sample value (as in original code).

sivaifx · 2026-01-05T09:06:09Z

examples/buttons/buttons_main.c

    }

-  /* Ignore the default signal action */
+    {


Below section of code related to signal set looks like a redundant one. Is this really needed?

sivaifx · 2026-01-05T09:29:47Z

examples/buttons/buttons_main.c

+          goto errout_with_fd;
+        }
+
+      if (!(fds[0].revents & POLLIN))


Is this to handle spurious wakeup? If so, comment shall be added before continue as /* Spurious wakeup? */

sivaifx · 2026-01-07T16:10:41Z

examples/buttons/buttons_main.c

+#ifdef CONFIG_EXAMPLES_BUTTONS_NAMES
+              process_sample(sample, &oldsample);
+#else
+              printf("Sample = %jd\n", (intmax_t)sample);


Don't replicate this section of code as this is already part of process_sample. Your first commit is correct and I believe you misunderstood Parthiban's comment. His comment is to move variable declaration "int i" inside CONFIG_EXAMPLES_BUTTONS_NAMES and not to move the entire process_sample inside this macro. Fix this.

sivaifx

@parthitce - Compliance check has passed and only CI has failed. Hope this is fine.

nishantifx · 2026-01-09T05:17:46Z

Added a small follow-up fix: sample values were printing repeatedly in loop. Now printing the sample value only when it changes to avoid redundant output.

nishantifx · 2026-01-19T06:49:54Z

@parthitce - please check the latest updates. If everything looks good, could you kindly proceed with the approval?

parthitce · 2026-01-21T08:26:58Z

@parthitce - please check the latest updates. If everything looks good, could you kindly proceed with the approval?

Could you please squash the commits? Otherwise good

nishantifx · 2026-01-21T09:25:45Z

@parthitce - Squashed all 5 commits into one and updated the PR. Please have a look.

- Refactor button handling to properly support poll mode and ensure reliable press/release detection using process_sample() - Rework button state processing structure based on review feedback and align code with NuttX coding standards (include order, formatting, and whitespace cleanup) - Move the loop index variable declaration inside the CONFIG_EXAMPLES_BUTTON_NAMES conditional to ensure variables used by the directive remain properly scoped and avoid configuration-related build warnings - Fix logic that caused sample values to be printed repeatedly in a loop and update output to print only when values change - Final cleanup of sample print logic and minor refactoring for consistency and clarity Tested on: Infineon’s AURIX™ TC397 Evaluation Board: KIT_A2G_TC397_5V_TFT and STM32F4Discovery Signed-off-by: Nishant-IFX <Nishant.Kumar@infineon.com>

nishantifx requested review from parthitce and sivaifx December 11, 2025 10:02

nishantifx assigned parthitce and sivaifx Dec 11, 2025

parthitce requested changes Dec 18, 2025

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github-actions bot added Area: Examples Size: M labels Dec 19, 2025

sivaifx requested changes Jan 5, 2026

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sivaifx requested changes Jan 7, 2026

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sivaifx approved these changes Jan 8, 2026

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sivaifx approved these changes Jan 9, 2026

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nishantifx force-pushed the dev/infineon/btn-app-poll-fix branch from d229c96 to b628c19 Compare January 21, 2026 09:22

nishantifx force-pushed the dev/infineon/btn-app-poll-fix branch from b628c19 to f4bbdea Compare January 21, 2026 09:47

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nishantifx commented Dec 11, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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nishantifx commented Dec 11, 2025 •

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