Added input parameter for vref constant #featureadd

Added an option to change the vref constant over serial

firmware/AVR-Source/Pyr0_Piezo_Sensor_v2.x.x/src/Pyr0_Piezo_Sensor_V2.x.x.cpp

@@ -27,16 +27,18 @@
   by Alan "pyr0ball" Weinstock
 
   This code is in the public domain.
-*/
+------------------------------------------------------------*/
 
-/* To set the below parameters using serial input, use the following:
+/*-----------------------------------------------------------
+To set the below parameters using serial input, use the following:
 
 To change trigger active duration: TRG_D [integer for milliseconds]
 To change gain factor: GAIN_F [integer for gain state - see note*]
 To change ADC hysteresis value: HYST [integer]
 To change sensor input pullup vRef low threshold: VFOL [integer in millivolts]
 To change comparator trigger high threshold: VCOMP [integer in millivolts]
 To change the duration between ADC measurements: LOOP_D [integer in milliseconds]
+To update the internal vRef constant value **(see notes below): CONST [long value]
 
 You can also enable or disable DEBUG output with: DEBUG [0|1]
 
@@ -45,7 +47,6 @@ You can query the current state (including ADC measurements) with: STATE
 
 To reset all settings to defaults, use: RESET
 
-
 These commands should be wrapped in this format:
 CMD INT
 
@@ -62,9 +63,24 @@ The gain STATE is representative of these values:
 2 = 4.33x
 3 = 6x
 4 = 11x
-*/
 
-/*------------------------------------------------------------*/
+**Note for calibrating internal 1.1v vRef:
+The ADC reading function assumes an "ideal" multiplier constant. Each Atmega
+chip is slightly different, so it won't be completely accurate without tuning.
+Most of the time this won't be necessary, so don't mess with this if you don't
+know what you're doing!
+The reading can be fine-tuned by using a multimeter, and this equation:
+
+scale_constant = internal1.1Ref * 1023 * 1000
+
+where
+
+internal1.1Ref = 1.1 * Vcc1 (per voltmeter) / Vcc2 (per readVcc() function)
+
+If the scale_constant calculated is different from the default 1125300,
+update the voltMeterConstant variable in pP_config.h with the correct value
+
+------------------------------------------------------------*/
 
 // Debug output toggle. Uncomment to enable
 #define DEBUG true

firmware/AVR-Source/Pyr0_Piezo_Sensor_v2.x.x/src/pP_config.h

@@ -47,11 +47,13 @@
  extern int Debug;
 #endif
 
+#define VM_CONST_ADDRESS 28
 #if !(defined(voltMeterConstant))
   extern long voltMeterConstant = 1125300L; // For fine tuning input voltage sense
 #endif
 
 #ifdef I2C_INPUT
+  #define I2C_SLAVE_ADDRESS 24
   #if !(defined(pP_i2c_address))
     extern byte pP_i2c_address = 0xa0;     // I2C Bus Address
   #endif

firmware/AVR-Source/Pyr0_Piezo_Sensor_v2.x.x/src/pP_serial.h

@@ -118,6 +118,16 @@ void updateHysteresis() {
 }
 /*------------------------------------------------*/
 
+void updateConstant() {
+  if (serialInt >= 0)
+  {
+    voltMeterConstant = serialInt;
+    EEPROM.put(VM_CONST_ADDRESS, voltMeterConstant);
+  }
+}
+
+/*------------------------------------------------*/
+
 void updateDebug() {
   if (serialInt > 0) {
     Debug = 1;
@@ -168,6 +178,9 @@ void serialPrintConfig()
 
   Serial.print("HYST ");
   Serial.println(Hyst);
+
+  Serial.print("VM_CONST ");
+  Serial.println(voltMeterConstant);
 }
 
 void serialPrintState()
@@ -212,6 +225,9 @@ void updateParams() {
   else if (strcmp(serialMessageIn, "HYST") == 0) {
     updateHysteresis();
   }
+  else if (strcmp(serialMessageIn, "CONST") == 0) {
+    updateConstant();
+  }
   else if (strcmp(serialMessageIn, "DEBUG") == 0) {
     updateDebug();
   }