Add NAU7802 external calibration (true Zero / Tare).

Author: PaulZC

Firmware/OpenLog_Artemis/autoDetect.ino

@@ -748,11 +748,16 @@ void configureDevice(node * temp)
 
         delay(sensor->getLDORampDelay()); // Wait for LDO to ramp
 
-        if (sensorSetting->useCalibrationInternal)
+        if (sensorSetting->calibrationMode == 1) //Internal calibration
         {
           sensor->getWeight(true, 10); //Flush
 
-          sensor->calibrateAFE(); //Recalibrate after changing gain / sample rate          
+          sensor->calibrateAFE(NAU7802_CALMOD_INTERNAL); //Recalibrate after changing gain / sample rate          
+        }
+        else if (sensorSetting->calibrationMode == 2) //Use saved or default external calibration
+        {
+          sensor->set24BitRegister(NAU7802_OCAL1_B2, sensorSetting->offsetReg);
+          sensor->set32BitRegister(NAU7802_GCAL1_B3, sensorSetting->gainReg);
         }
 
         sensor->getWeight(true, 10); //Flush

Firmware/OpenLog_Artemis/menuAttachedDevices.ino

@@ -937,6 +937,7 @@ void menuConfigure_NAU7802(void *configPtr)
       SerialPrintf2("\r\nScale calibration factor: %s\r\n", tempStr);
 
       SerialPrintf2("Scale zero offset: %d\r\n", sensorConfig->zeroOffset);
+      SerialPrintf2("Scale offset register: %d\r\n", sensor->get24BitRegister(NAU7802_OCAL1_B2));
 
       sensor->getWeight(true, 10); //Flush
       olaftoa(sensor->getWeight(true, sensorConfig->averageAmount), tempStr, sensorConfig->decimalPlaces, sizeof(tempStr) / sizeof(char));
@@ -1024,9 +1025,10 @@ void menuConfigure_NAU7802(void *configPtr)
       olaftoa(LDO, tempStr, 1, sizeof(tempStr) / sizeof(char));
       SerialPrintf2("9) LDO voltage: %s\r\n", tempStr);
     }
-    SerialPrint(F("10) Use internal calibration: "));
-    if (sensorConfig->useCalibrationInternal == true) SerialPrintln(F("Enabled"));
-    else SerialPrintln(F("Disabled"));
+    SerialPrint(F("10) Calibration mode: "));
+    if (sensorConfig->calibrationMode == 0) SerialPrintln(F("None"));
+    else if (sensorConfig->calibrationMode == 1) SerialPrintln(F("Internal"));
+    else SerialPrintln(F("External"));
 
     SerialPrintln(F("x) Exit"));
 
@@ -1049,6 +1051,16 @@ void menuConfigure_NAU7802(void *configPtr)
 
         sensor->getWeight(true, 10); //Flush
 
+        if (sensorConfig->calibrationMode == 2) //External calibration
+        {
+          sensor->calibrateAFE(NAU7802_CALMOD_OFFSET); //External offset calibration
+
+          sensorConfig->offsetReg = sensor->get24BitRegister(NAU7802_OCAL1_B2); // Save new offset
+          sensorConfig->gainReg = sensor->get32BitRegister(NAU7802_GCAL1_B3); // This should not have changed, but read it anyway
+
+          sensor->getWeight(true, 10); //Flush
+        }
+
         sensor->calculateZeroOffset(sensorConfig->averageAmount); //Zero or Tare the scale
 
         sensorConfig->zeroOffset = sensor->getZeroOffset();
@@ -1132,11 +1144,11 @@ void menuConfigure_NAU7802(void *configPtr)
 
         sensor->setGain(sensorConfig->gain);
 
-        if (sensorConfig->useCalibrationInternal)
+        if (sensorConfig->calibrationMode == 1) //Internal calibration
         {
           sensor->getWeight(true, 10); //Flush
 
-          sensor->calibrateAFE(); //Recalibrate after changing gain / sample rate
+          sensor->calibrateAFE(NAU7802_CALMOD_INTERNAL); //Recalibrate after changing gain / sample rate          
         }
 
         SerialPrintln(F("\r\n\r\nGain updated. Please zero and calibrate the scale\r\n\r\n"));
@@ -1151,13 +1163,14 @@ void menuConfigure_NAU7802(void *configPtr)
 
         sensor->setSampleRate(sensorConfig->sampleRate);
 
-        if (sensorConfig->useCalibrationInternal)
+        if (sensorConfig->calibrationMode == 1) //Internal calibration
         {
           sensor->getWeight(true, 10); //Flush
 
-          sensor->calibrateAFE(); //Recalibrate after changing gain / sample rate
+          sensor->calibrateAFE(NAU7802_CALMOD_INTERNAL); //Recalibrate after changing gain / sample rate          
         }
 
+        // Limit averageAmount (to prevent getWeight timing out after 1s)
         if ((sensorConfig->sampleRate) == 0 && (sensorConfig->averageAmount > 9))
           sensorConfig->averageAmount = 9;
         else if ((sensorConfig->sampleRate) == 1 && (sensorConfig->averageAmount > 19))
@@ -1179,20 +1192,22 @@ void menuConfigure_NAU7802(void *configPtr)
 
         sensor->setLDO(sensorConfig->LDO);
 
-        if (sensorConfig->useCalibrationInternal)
+        if (sensorConfig->calibrationMode == 1) //Internal calibration
         {
           delay(sensor->getLDORampDelay()); // Wait for LDO to ramp before attempting calibrateAFE
 
           sensor->getWeight(true, 10); //Flush
 
-          sensor->calibrateAFE(); //Recalibrate after changing gain / sample rate
+          sensor->calibrateAFE(NAU7802_CALMOD_INTERNAL); //Recalibrate after changing gain / sample rate          
         }
 
         SerialPrintln(F("\r\n\r\nLDO updated. Please zero and calibrate the scale\r\n\r\n"));
       }
       else if (incoming == 10)
       {
-        sensorConfig->useCalibrationInternal ^= 1;
+        sensorConfig->calibrationMode += 1;
+        if (sensorConfig->calibrationMode == 3)
+          sensorConfig->calibrationMode = 0;
 
         sensor->reset();
         sensor->powerUp();
@@ -1210,11 +1225,11 @@ void menuConfigure_NAU7802(void *configPtr)
 
         delay(sensor->getLDORampDelay()); // Wait for LDO to ramp before attempting calibrateAFE
 
-        if (sensorConfig->useCalibrationInternal)
+        if (sensorConfig->calibrationMode == 1) //Internal calibration
         {
           sensor->getWeight(true, 10); //Flush
 
-          sensor->calibrateAFE(); //Recalibrate after changing gain / sample rate
+          sensor->calibrateAFE(NAU7802_CALMOD_INTERNAL); //Recalibrate after changing gain / sample rate          
         }
 
         sensor->getWeight(true, 10); //Flush

Firmware/OpenLog_Artemis/nvm.ino

@@ -527,7 +527,9 @@ void recordDeviceSettingsToFile()
             settingsFile.println((String)base + "sampleRate=" + nodeSetting->sampleRate);
             settingsFile.println((String)base + "gain=" + nodeSetting->gain);
             settingsFile.println((String)base + "LDO=" + nodeSetting->LDO);
-            settingsFile.println((String)base + "useCalibrationInternal=" + nodeSetting->useCalibrationInternal);
+            settingsFile.println((String)base + "calibrationMode=" + nodeSetting->calibrationMode);
+            settingsFile.println((String)base + "offsetReg=" + nodeSetting->offsetReg);
+            settingsFile.println((String)base + "gainReg=" + nodeSetting->gainReg);
           }
           break;
         case DEVICE_DISTANCE_VL53L1X:
@@ -1039,8 +1041,12 @@ bool parseDeviceLine(char* str) {
             nodeSetting->gain = d;
           else if (strcmp(deviceSettingName, "LDO") == 0)
             nodeSetting->LDO = d;
-          else if (strcmp(deviceSettingName, "useCalibrationInternal") == 0)
-            nodeSetting->useCalibrationInternal = d;
+          else if (strcmp(deviceSettingName, "calibrationMode") == 0)
+            nodeSetting->calibrationMode = d;
+          else if (strcmp(deviceSettingName, "offsetReg") == 0)
+            nodeSetting->offsetReg = d;
+          else if (strcmp(deviceSettingName, "gainReg") == 0)
+            nodeSetting->gainReg = d;
           else
             SerialPrintf2("Unknown device setting: %s\r\n", deviceSettingName);
         }

Firmware/OpenLog_Artemis/settings.h

@@ -112,7 +112,9 @@ struct struct_NAU7802 {
   int sampleRate = 3; //Library says possible values are: 10(0), 20(1), 40(2), 80(3), 320(7)
   int gain = 7; //Library says possible values are: 1(0), 2(1), 4(2), 8(3), 16(4), 32(5), 64(6), 128(7)
   int LDO = 5; //LDO voltage. Only 3.3(4), 3.0(5), 2.7(6), 2.4(7) make sense here
-  bool useCalibrationInternal = true; //Use CALMOD / CALS (calibrateAFE)
+  int calibrationMode = 1; //0: None; 1: Use CALMOD / CALS (calibrateAFE) Internal; 2: Use CALMOD / CALS (calibrateAFE) External
+  int32_t offsetReg = 0; //Value for the NAU7802 offset register
+  uint32_t gainReg = 0x00800000; //Value for the NAU7802 gain register
   unsigned long powerOnDelayMillis = minimumQwiicPowerOnDelay; // Wait for at least this many millis before communicating with this device. Increase if required!
 };