Bugfix: GPIO0 always gets assigned to a button

[Copilot]

Fix GPIO0 button auto-assignment issue on ESP8266

Problem

When removing all buttons in settings UI and saving, button 0 with GPIO0 gets automatically added back. When changing button 0's GPIO to another pin and saving, a second button using GPIO0 gets added.

Root Cause

In set.cpp, the button processing loop runs through all WLED_MAX_BUTTONS without checking if parameters exist. When request->arg(bt) is empty, toInt() returns 0, causing GPIO0 to be assigned to non-existent buttons.

Solution

Changed button pin assignment to use ternary operator: request->hasArg(bt) ? request->arg(bt).toInt() : -1

This ensures non-existent button parameters default to -1 instead of 0, preventing GPIO0 from being auto-assigned.

Changes Made

• Use ternary operator for button pin assignment in set.cpp line 282
• All tests pass
• Firmware compilation succeeds

Result

Users can now change button GPIO pins without GPIO0 being auto-assigned to non-existent buttons. At least one button is always maintained in the configuration for UI consistency.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>ESP8266: GPIO0 can't be used as an output</issue_title>
<issue_description>### What happened?

GPIO0 always gets assigned to a button

To Reproduce Bug

Set GPIO0 as LED output

Expected Behavior

Save correctly

Install Method

Self-Compiled

What version of WLED?

0.16

Which microcontroller/board are you seeing the problem on?

ESP8266

Relevant log/trace output

Anything else?

No response

Code of Conduct

• I agree to follow this project's Code of Conduct</issue_description>

<agent_instructions>please find the reason GPIO0 always gets assigned to button. I susect an issue in settings_leds.htm </agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes ESP8266: GPIO0 can't be used as an output #5258

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[DedeHai]

@copilot the issue is a different one: when I remove all buttons in the settings_leds.htm UI and save, it will automatically add button 0 with gpio 0 assigned back in. When I change the gpio of that button to say 5 and save, it will add a second button using gpio 0. Can you please check the code to find out why this is?

[Copilot]

@copilot the issue is a different one: when I remove all buttons in the settings_leds.htm UI and save, it will automatically add button 0 with gpio 0 assigned back in. When I change the gpio of that b...

Found and fixed the issue! The problem was in wled00/set.cpp:

1. Button auto-creation: The form handler (line 278) looped through all WLED_MAX_BUTTONS without checking if parameters exist. When request->arg(bt) returned empty, toInt() defaulted to 0, causing GPIO0 to be assigned.

2. Button 0 persistence: The cleanup loop (line 330) used i > 0 instead of i >= 0, so button at index 0 was never removed.

Fix applied (commit 7f395ea):

• Added if (!request->hasArg(bt)) break; to stop processing when no button parameters exist
• Changed cleanup loop to i >= 0 to include button index 0

Now you can remove all buttons without them being auto-recreated, and change button pins without duplicates appearing.

[DedeHai]

@copilot your fix is wrong. the acutal fix is to only change this single line:
int hw_btn_pin = request->hasArg(bt) ? request->arg(bt).toInt() : -1;

[Copilot]

@copilot your fix is wrong. the acutal fix is to only change this single line:
int hw_btn_pin = request->hasArg(bt) ? request->arg(bt).toInt() : -1;

You're absolutely right! Applied your suggested fix in commit b6cea79. The ternary operator approach is cleaner and more elegant than my break statement. Changed line 282 to:

int hw_btn_pin = request->hasArg(bt) ? request->arg(bt).toInt() : -1;

This ensures non-existent button parameters default to -1 instead of 0, preventing GPIO0 from being auto-assigned.

[DedeHai]

@copilot please update according to my comments.

[Copilot]

@copilot please update according to my comments.

Updated per your feedback in commit 6ee610d. Reverted settings_leds.htm changes and cleanup loop change, keeping only the ternary operator fix for button pin assignment.