I2C hang recover function added

Dependencies:   UniGraphic mbed vt100

In this version, check_i2c_pins function was added in edge_mgr.cpp.

プログラムの起動時、I2Cモジュールを初期化する前に、I2Cに使用するピンの電位を確認し
もし一方でも Low に張り付いていた場合、SCL を GPIO 出力に設定して 
所定回数 (I2C_UNLOCK_TRIAL_CYCLE) 反転させることにより、疑似リセットクロックを生成します。

その後は、通常の起動手順に復帰し、以降はこれまでと同様の動作をします。

Revision:
0:d895cd1cd897
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Apr 03 08:30:29 2018 +0000
@@ -0,0 +1,130 @@
+#include "mbed.h"
+#include "vt100.h"
+#include "afLib.h"
+#include "af_mgr.h"
+#include "edge_mgr.h"
+#include "edge_time.h"
+#include "edge_reset_mgr.h"
+/**
+ * afero poc1.5 25-Dec-2017 version
+ * from this version, watch dog timer joined again.
+ */
+
+vt100   *tty = 0 ;
+uint32_t wait_tolerance = 500 ; /* 5sec */
+uint32_t connect_tolerance = 60 ; /* after 60 trials, reboot */
+uint32_t wait_count = 0 ;
+uint32_t connect_trial_count = 0 ;
+
+/**
+ * wait_connection
+ * When gConnected == false, which is connection is lost.
+ * Each 5sec check attribute ATTR_WIFI_STDY_STATE to see
+ * if the connection has recovered.
+ * Meantime even if connection is established communicated
+ * data is invalid, so AF_SYSTEM_ASR_STATE is also
+ * checked for gLinked ;
+ * And in case connect_tolerance trials failed
+ * try to reboot the system if it can improve the situation.
+ */
+void wait_connection(void)
+{
+    int result ;
+    wait_count++ ;
+    if (wait_count > wait_tolerance) {
+        reset_watch_dog() ;
+        if (gConnected == false) {
+            result = afero->getAttribute(ATTR_WIFI_STDY_STATE) ;
+            if (result != afSUCCESS) {
+                print_af_error(result) ;
+            }
+        }
+        if (gLinked == false) {
+            result = afero->getAttribute(AF_SYSTEM_ASR_STATE) ;
+            if (result != afSUCCESS) {
+                print_af_error(result) ;
+            }
+        }
+        connect_trial_count++ ;
+        if (connect_trial_count > connect_tolerance) {
+            reboot_edge() ;
+        }
+        wait_count = 0 ;
+    }
+}
+
+void init_hardware(void)
+{
+    int i ;
+    int result ;
+    
+        reset_watch_dog() ;
+    init_display() ;
+        reset_watch_dog() ;
+    init_aflib() ;
+        reset_watch_dog() ;
+    init_sensors() ;
+        reset_watch_dog() ;
+    init_timer() ;
+
+    while(true) {
+        reset_watch_dog() ;
+        for (i = 0 ; i < 10 ; i++ ) {
+            afero->loop() ;
+            reset_watch_dog() ;
+        }
+        if ((gLinked == true)&&(gConnected == true)) {
+            wait_count = 0 ;
+            connect_trial_count = 0 ;
+            if (afero->isIdle()) {
+                result = init_edge_attribute() ;
+                if (result == 0) {
+                    break ;
+                }
+            }
+        } else { /* gLinked == false */
+            wait_connection() ;
+        }
+        wait_ms(10) ;
+    }
+    do {
+//    while(!afero->isIdle()) {
+        reset_watch_dog() ;
+        for (i = 0 ; i < 10 ; i++ ) { 
+            afero->loop() ;
+            wait_ms(100) ; 
+        }
+    } while(!afero->isIdle()) ;
+    edge_mgr_status = EDGE_MGR_RUNNING ;
+}
+
+// main() runs in its own thread in the OS
+int main() {
+    static uint32_t count_robin = 0 ;
+
+    tty = new vt100() ;
+//    tty->cls() ;
+    printf("Afero test program (ver. %s) started\n", __DATE__) ;   
+    printf("=== Reset Reason ===\n") ;
+    print_reset_reason() ;
+    printf("====================\n") ;
+
+    init_hardware() ;
+    
+    edge_splash() ;
+                    
+    while (true) {
+        count_robin++ ;
+        afero->loop() ;
+        if ((gLinked == true)&&(gConnected == true)) {
+            wait_count = 0 ;
+            connect_trial_count = 0 ;
+            if (afero->isIdle()) {
+                edge_loop(count_robin) ;
+            }
+        } else { /* gLinked == false */
+            wait_connection() ;      
+        }
+        wait_ms(10) ;
+    }
+}