Clanker powered plugin.

When you compile firmware, put the files with the plugins and add the following to your plugins file:

#include "settings_lock.h"

" include settings_lock_init();

How it works

Stream interception is the core mechanism. grblHAL exposes hal.stream.read as a swappable function pointer — the same trick the SD-card plugin uses. We replace it with intercepted_read(), which buffers incoming characters until a full line is assembled, then either blocks it or releases it one character at a time to the protocol loop.

What gets blocked when locked:

• $N=value — any numbered setting write
• $RST=* — settings reset

What always passes through:

• Real-time bytes (!, ?, ~, Ctrl-X, 0x80–0xBF) — bypass buffering entirely, so feed-hold and soft-reset always work
• All G-code
• Read-only $ commands ($$, $G, $I, $H, $X, etc.)

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Commands

Command

Effect

$SETPWD=mypassword

Set the password (first time, or while unlocked)

$UNLOCK=mypassword

Unlock this session

$LOCK

Re-lock immediately

$SETPWD=

Clear password — disables locking

The lock re-engages automatically on every soft reset (Ctrl-X) via grbl.on_reset, so it can't be bypassed that way.