tested ELM327 connection and refactored bt driver to include elm327

due_obd2/obd2_elm327.h

@@ -0,0 +1,97 @@
+/*
+BT module settings (AT mode):
++NAME=OBD2_BT
++VER=8.0.2,FSC-BT836B
++MAC=DC0D30000FA9
++BAUD=115200
++PIN=1189
+
+https://forum.arduino.cc/t/trying-to-connect-hc-05-to-bluetooth-obd2-interface-elm-327/643301/13
+https://stackoverflow.com/questions/59125470/connecting-to-elm327-bt-with-hc05-stm32-not-as-simply-as-look-like
+https://electronics.stackexchange.com/questions/101572/hc-05-bluetooth-module-not-responding-to-certain-commands
+
+
+OBD2 INQ: 0010:CC:4F3603,0,FF9C,OBDII
+AT+PAIR=0010,CC,4F3603,20
+
+AT Commands to connect permanently to the OBD2 module:
+    AT+RESET
+    AT+ORGL (Set to original)
+    AT+ROLE=1 (Set to Master)
+    AT+CMODE=0 (Set connect to a specific address)
+    AT+BIND=dc0d,30,000fa9
+    AT+INIT (Need to connect)
+    AT+PAIR=dc0d,30,000fa9,30 (,30 means 30 second timeout)
+                                                            
+
+Be sure to disconnect the TX and RX pins from the BT module when programming the arduino.
+*/
+#ifndef OBD2_ELM327_H
+#define OBD2_ELM327_H
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+// #include <Arduino.h>
+// #include "obd2_util.h"
+
+/* pins */
+#define PIN_BT_RX 19
+#define PIN_BT_TX 18
+
+#define BT_STATE_PIN 3 /* state connection pin from bluetooth module -> level high on connected */
+
+#define BT_BAUD 115200
+#define ELM327_BAUD 115200
+
+#define BT_STATE_LENGTH 13 /* length of the string identifier used for the states */
+
+#define ELM327_SERIAL Serial2
+
+enum BluetoothState
+{
+    BT_INITIALISING = 0,
+    BT_CONNECTING = 1,
+    BT_CONNECTED = 2
+};
+
+/**
+ * @brief struct to hold bluetooth module data
+ * 
+ * @param state the current state of the bluetooth module
+ * @param on_state_change function pointer to the function to be called when the state changes
+ */
+typedef struct obt2_elm327_tag
+{
+    enum BluetoothState bt_state;
+    void (*on_state_change)();
+} obd2_elm327_t;
+
+/**
+ * @brief initializes the bluetooth module driver   
+ * 
+ * @param elm327 pointer to struct holding bluetooth driver data
+ */
+void obd2_elm327_init(obd2_elm327_t *elm327);
+
+/**
+ * @brief processes the bluetooth module communication with the OBD2 reader
+ * 
+ * @param bt pointer to struct holding bluetooth driver data
+ */
+void obd2_elm327_process(obd2_elm327_t *elm327);
+
+/**
+ * @brief copies the current state of the bluetooth module to the state string
+ * 
+ * @param elm327 pointer to struct holding bluetooth driver data
+ * @param state resulting string to hold the text representation of the state
+ */
+void obd2_elm327_get_state(obd2_elm327_t *elm327, char *state);
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif // OBD2_ELM327_H