add start of state machine

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "files.associations": {
+        "statemachine.h": "c"
+    }
+}

due_obd2/due_obd2.ino

@@ -12,6 +12,7 @@ Program to create a car monitor display using:
 
 #include "obd2_display.h"
 #include "obd2_timer.h"
+#include "statemachine.h"
 
 #define DEBUG 1
 // #define RTT_MR 0x400E1A30U

due_obd2/statemachine.c

@@ -0,0 +1,19 @@
+#include "statemachine.h"
+
+state_t none_state = 
+{
+    .id = 0,
+    .on_enter = &__state_none,
+    .on_run = &__state_none,
+    .on_exit = &__state_none,
+
+}
+statemachine_t statemachine = 
+{
+    .current_state = 
+};
+
+void statemachine_init()
+{
+
+}

due_obd2/statemachine.h

@@ -0,0 +1,59 @@
+#ifndef STATEMACHINE_H
+#define STATEMACHINE_H
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+#include "Arduino.h"
+
+/* two displays:
+    - initialisation display, shows the state of booting up
+    - main display, shows the data from the OBD2 scanner
+
+    each state has a function that can be called when it enters that state, while it's running and when it exits that state
+    Example: https://stackoverflow.com/questions/1371460/state-machines-tutorials
+*/
+
+/**
+ * @brief      State struct. Contains the id of the state, and the functions that are called when the state is entered, running and exited.
+*/
+typedef struct SM_STATE
+{
+    int id;
+    void (*on_enter)();
+    void (*on_run)();
+    void (*on_exit)();
+} state_t;
+
+/**
+ * @brief      Transition struct. Contains the id of the state it transitions to, and the next state.
+*/
+typedef struct SM_TRANSITION
+{
+    int state_id;
+    state_t *next_state;
+} transition_t;
+
+/**
+ * @brief      State machine struct. Contains the current state and the transitions.
+*/
+typedef struct SM_STATE_MACHINE
+{
+    state_t *current_state;
+    transition_t *transitions; /* Transitions between states. Every state's ID is also it's position in the array.*/
+
+} statemachine_t;
+
+/**
+ * @brief      Initialises the state machine. Initializes the statemachine struct.
+ */
+void statemachine_init();
+void __state_none() 
+{
+    /* do nothing*/
+}
+
+#ifdef __cplusplus
+ }
+ #endif
+#endif // !STATEMACHINE_H