Add HX711 weight restore after controlled restart or after power restore just before executing command Sensor34 7 (#5367, #5786)

Add HX711 weight restore after controlled restart or after power restore just before executing command Sensor34 7 (#5367, #5786)

sonoff/_changelog.ino

@@ -2,6 +2,7 @@
  * Add command SetOption64 0/1 to switch between "-" or "_" as sensor index separator impacting DS18X20, DHT, BMP and SHT3X sensor names (#5689)
  * Add initial support for Scripts as replacement for Rules. Default disabled but can be enabled in my_user_config.h (#5689)
  * Add rule System#Save executed just before a planned restart
+ * Add HX711 weight restore after controlled restart or after power restore just before executing command Sensor34 7 (#5367, #5786)
  *
  * 6.5.0.10 20190513
  * Enable ADC0 by default in my_user_config.h (#5671)

sonoff/settings.h

@@ -345,7 +345,7 @@ struct SYSCFG {
   uint16_t      weight_max;                // 7BE Total max weight in kilogram
   unsigned long weight_reference;          // 7C0 Reference weight in gram
   unsigned long weight_calibration;        // 7C4
-  unsigned long energy_frequency_calibration;  // 7C8
+  unsigned long energy_frequency_calibration;  // 7C8 also used by HX711 to save last weight
   uint16_t      web_refresh;               // 7CC
   char          mems[MAX_RULE_MEMS][10];   // 7CE
   char          rules[MAX_RULE_SETS][MAX_RULE_SIZE]; // 800 uses 512 bytes in v5.12.0m, 3 x 512 bytes in v5.14.0b

sonoff/xsns_34_hx711.ino

@@ -62,6 +62,7 @@ enum HxCalibrationSteps { HX_CAL_END, HX_CAL_LIMBO, HX_CAL_FINISH, HX_CAL_FAIL,
 const char kHxCalibrationStates[] PROGMEM = D_HX_CAL_FAIL "|" D_HX_CAL_DONE "|" D_HX_CAL_REFERENCE "|" D_HX_CAL_REMOVE;
 
 long hx_weight = 0;
+long hx_last_weight = 0;
 long hx_sum_weight = 0;
 long hx_offset = 0;
 long hx_scale = 1;
@@ -116,11 +117,18 @@ long HxRead()
 
 /*********************************************************************************************/
 
-void HxReset(void)
+void HxResetPart(void)
 {
   hx_tare_flg = true;
   hx_sum_weight = 0;
   hx_sample_count = 0;
+  hx_last_weight = 0;
+}
+
+void HxReset(void)
+{
+  HxResetPart();
+  Settings.energy_frequency_calibration = 0;
 }
 
 void HxCalibrationStateTextJson(uint8_t msg_id)
@@ -147,6 +155,7 @@ void HxCalibrationStateTextJson(uint8_t msg_id)
  * Sensor34 5 <weight in gram>     - Set max weight
  * Sensor34 6                      - Show item weigth in decigram
  * Sensor34 6 <weight in decigram> - Set item weight
+ * Sensor34 7                      - Save current weight to be used as start weight on restart
 \*********************************************************************************************/
 
 bool HxCommand(void)
@@ -199,6 +208,10 @@ bool HxCommand(void)
       }
       show_parms = true;
       break;
+    case 7:  // WeightSave
+      Settings.energy_frequency_calibration = hx_weight;
+      Response_P(S_JSON_SENSOR_INDEX_SVALUE, XSNS_34, D_JSON_DONE);
+      break;
     default:
       serviced = false;
   }
@@ -238,8 +251,7 @@ void HxInit(void)
       if (!Settings.weight_reference) { Settings.weight_reference = HX_REFERENCE; }
       hx_scale = Settings.weight_calibration;
       HxRead();
-      HxReset();
+      HxResetPart();
-
       hx_type = 1;
     }
   }
@@ -254,7 +266,16 @@ void HxEvery100mSecond(void)
     long average = hx_sum_weight / hx_sample_count;  // grams
     long value = average - hx_offset;                // grams
     hx_weight = value / hx_scale;                    // grams
-    if (hx_weight < 0) { hx_weight = 0; }
+    if (hx_weight < 0) {
+      if (Settings.energy_frequency_calibration) {
+        long difference = Settings.energy_frequency_calibration + hx_weight;
+        hx_last_weight = difference;
+        if (difference < 0) { HxReset(); }           // Cancel last weight as there seems to be no more weight on the scale
+      }
+      hx_weight = 0;
+    } else {
+      hx_last_weight = Settings.energy_frequency_calibration;
+    }
 
     if (hx_tare_flg) {
       hx_tare_flg = false;
@@ -313,6 +334,8 @@ void HxEvery100mSecond(void)
       if (!hx_calibrate_timer) {
         hx_calibrate_step = HX_CAL_END;              // End of calibration
       }
+    } else {
+      hx_weight += hx_last_weight;                   // grams
     }
 
     hx_sum_weight = 0;
@@ -320,6 +343,12 @@ void HxEvery100mSecond(void)
   }
 }
 
+void HxSaveBeforeRestart()
+{
+  Settings.energy_frequency_calibration = hx_weight;
+  hx_sample_count = HX_SAMPLES +1;                   // Stop updating hx_weight
+}
+
 #ifdef USE_WEBSERVER
 const char HTTP_HX711_WEIGHT[] PROGMEM =
   "{s}HX711 " D_WEIGHT "{m}%s " D_UNIT_KILOGRAM "{e}";  // {s} = <tr><th>, {m} = </th><td>, {e} = </td></tr>
@@ -484,6 +513,9 @@ bool Xsns34(uint8_t function)
       case FUNC_JSON_APPEND:
         HxShow(1);
         break;
+      case FUNC_SAVE_BEFORE_RESTART:
+        HxSaveBeforeRestart();
+        break;
 #ifdef USE_WEBSERVER
       case FUNC_WEB_SENSOR:
         HxShow(0);