Add globa Panic() function

The intent is to halt the firmware while retaining the reporting capabilities and blinking LEDs

src/logic/command_base.cpp

@@ -2,6 +2,7 @@
 #include "../modules/idler.h"
 #include "../modules/selector.h"
 #include "../modules/motion.h"
+#include "../modules/leds.h"
 
 namespace logic {
 
@@ -76,6 +77,15 @@ bool CommandBase::Step() {
     return StepInner();
 }
 
+void CommandBase::Panic(ErrorCode ec) {
+    state = ProgressCode::ERRInternal;
+    error = ec;
+    for (uint8_t i = 0; i < config::toolCount; ++i) {
+        ml::leds.SetMode(i, ml::green, ml::blink0);
+        ml::leds.SetMode(i, ml::red, ml::blink0);
+    }
+}
+
 bool CommandBase::CheckToolIndex(uint8_t index) {
     if (index >= config::toolCount) {
         error = ErrorCode::INVALID_TOOL;

src/logic/command_base.h

@@ -61,6 +61,14 @@ public:
     /// Please see ErrorCode for more details
     virtual ErrorCode Error() const { return error; }
 
+    /// Switches the state machine into an error state of code ec.
+    /// It shall be used to halt the firmware while retaining the capability of reporting the error state to the printer
+    /// - a kind of similar to runtime assertions.
+    /// Called from main.cpp's global funtion Panic() .
+    /// The derived state machines have no (implemented) way of getting out of this state (intentionally).
+    /// The only way out is to reset the board.
+    void Panic(ErrorCode ec);
+
 protected:
     /// @returns true if the slot/tool index is within specified range (0 - config::toolCount)
     /// If not, it returns false and sets the error to ErrorCode::INVALID_TOOL

src/main.cpp

@@ -31,6 +31,8 @@
 
 #include "version.h"
 
+#include "panic.h"
+
 /// Global instance of the protocol codec
 static mp::Protocol protocol;
 
@@ -331,6 +333,10 @@ bool CheckMsgs() {
     return false;
 }
 
+void Panic(ErrorCode ec) {
+    currentCommand->Panic(ec);
+}
+
 /// Main loop of the firmware
 /// Proposed architecture
 ///   checkMsgs();

src/panic.h

@@ -0,0 +1,10 @@
+#pragma once
+#include <stdint.h>
+#include "logic/error_codes.h"
+
+/// Switches the currently active logic state machine into an error state of code ec.
+/// It shall be used to halt the firmware while retaining the capability of reporting the error state to the printer
+/// - a kind of similar to runtime assertions.
+/// Implementation is in main.cpp, where we know the currently active logic state machine.
+/// The only way out is to reset the board.
+extern void Panic(ErrorCode ec);