Merge pull request #2 from cj8scrambler/master

Add non-blocking AFE calibration method

Author: nseidle

keywords.txt

@@ -33,6 +33,10 @@ setLDO	KEYWORD2
 setSampleRate	KEYWORD2
 setChannel	KEYWORD2
 calibrateAFE	KEYWORD2
+beginCalibrateAFE	KEYWORD2
+calAFEStatus		KEYWORD2
+waitForCalibrateAFE	KEYWORD2
+
 reset	KEYWORD2
 powerUp	KEYWORD2
 powerDown	KEYWORD2
@@ -124,3 +128,6 @@ NAU7802_PGA_PWR_PGA_CURR	LITERAL1
 NAU7802_PGA_PWR_ADC_CURR	LITERAL1
 NAU7802_PGA_PWR_MSTR_BIAS_CURR	LITERAL1
 NAU7802_PGA_PWR_PGA_CAP_EN	LITERAL1
+NAU7802_CAL_SUCCESS		LITERAL1
+NAU7802_CAL_IN_PROGRESS		LITERAL1
+NAU7802_CAL_FAILURE		LITERAL1

src/SparkFun_Qwiic_Scale_NAU7802_Arduino_Library.cpp

@@ -28,8 +28,10 @@ NAU7802::NAU7802()
 }
 
 //Sets up the NAU7802 for basic function
+//If initialize is true (or not specified), default init and calibration is performed
+//If initialize is false, then it's up to the caller to initalize and calibrate
 //Returns true upon completion
-bool NAU7802::begin(TwoWire &wirePort)
+bool NAU7802::begin(TwoWire &wirePort, bool initialize)
 {
   //Get user's options
   _i2cPort = &wirePort;
@@ -44,21 +46,24 @@ bool NAU7802::begin(TwoWire &wirePort)
 
   bool result = true; //Accumulate a result as we do the setup
 
-  result &= reset(); //Reset all registers
+  if (initialize)
+  {
+    result &= reset(); //Reset all registers
 
-  result &= powerUp(); //Power on analog and digital sections of the scale
+    result &= powerUp(); //Power on analog and digital sections of the scale
 
-  result &= setLDO(NAU7802_LDO_3V3); //Set LDO to 3.3V
+    result &= setLDO(NAU7802_LDO_3V3); //Set LDO to 3.3V
 
-  result &= setGain(NAU7802_GAIN_128); //Set gain to 128
+    result &= setGain(NAU7802_GAIN_128); //Set gain to 128
 
-  result &= setSampleRate(NAU7802_SPS_80); //Set samples per second to 10
+    result &= setSampleRate(NAU7802_SPS_80); //Set samples per second to 10
 
-  result &= setRegister(NAU7802_ADC, 0x30); //Turn off CLK_CHP. From 9.1 power on sequencing.
+    result &= setRegister(NAU7802_ADC, 0x30); //Turn off CLK_CHP. From 9.1 power on sequencing.
 
-  result &= setBit(NAU7802_PGA_PWR_PGA_CAP_EN, NAU7802_PGA_PWR); //Enable 330pF decoupling cap on chan 2. From 9.14 application circuit note.
+    result &= setBit(NAU7802_PGA_PWR_PGA_CAP_EN, NAU7802_PGA_PWR); //Enable 330pF decoupling cap on chan 2. From 9.14 application circuit note.
 
-  result &= calibrateAFE(); //Re-cal analog front end when we change gain, sample rate, or channel
+    result &= calibrateAFE(); //Re-cal analog front end when we change gain, sample rate, or channel
+  }
 
   return (result);
 }
@@ -80,25 +85,60 @@ bool NAU7802::available()
 }
 
 //Calibrate analog front end of system. Returns true if CAL_ERR bit is 0 (no error)
-//Takes approximately 344ms to calibrate
+//Takes approximately 344ms to calibrate; wait up to 1000ms.
 //It is recommended that the AFE be re-calibrated any time the gain, SPS, or channel number is changed.
 bool NAU7802::calibrateAFE()
 {
-  setBit(NAU7802_CTRL2_CALS, NAU7802_CTRL2); //Begin calibration
+  beginCalibrateAFE();
+  return waitForCalibrateAFE(1000);
+}
 
-  uint16_t counter = 0;
-  while (1)
+//Begin asynchronous calibration of the analog front end.
+// Poll for completion with calAFEStatus() or wait with waitForCalibrateAFE()
+void NAU7802::beginCalibrateAFE()
+{
+  setBit(NAU7802_CTRL2_CALS, NAU7802_CTRL2);
+}
+
+//Check calibration status.
+NAU7802_Cal_Status NAU7802::calAFEStatus()
+{
+  if (getBit(NAU7802_CTRL2_CALS, NAU7802_CTRL2))
+  {
+    return NAU7802_CAL_IN_PROGRESS;
+  }
+
+  if (getBit(NAU7802_CTRL2_CAL_ERROR, NAU7802_CTRL2))
   {
-    if (getBit(NAU7802_CTRL2_CALS, NAU7802_CTRL2) == false)
-      break; //Goes to 0 once cal is complete
+    return NAU7802_CAL_FAILURE;
+  }
+
+  // Calibration passed
+  return NAU7802_CAL_SUCCESS;
+}
+
+//Wait for asynchronous AFE calibration to complete with optional timeout.
+//If timeout is not specified (or set to 0), then wait indefinitely.
+//Returns true if calibration completes succsfully, otherwise returns false.
+bool NAU7802::waitForCalibrateAFE(uint32_t timeout_ms)
+{
+  uint32_t begin = millis();
+  NAU7802_Cal_Status cal_ready;
+
+  while ((cal_ready = calAFEStatus()) == NAU7802_CAL_IN_PROGRESS)
+  {
+    if ((timeout_ms > 0) && ((millis() - begin) > timeout_ms)) 
+    {
+      break;
+    }
     delay(1);
-    if (counter++ > 1000)
-      return (false);
   }
 
-  if (getBit(NAU7802_CTRL2_CAL_ERROR, NAU7802_CTRL2) == false)
-    return (true); //No error! Cal is good.
-  return (false);  //Cal error
+  if (cal_ready == NAU7802_CAL_SUCCESS)
+  {
+    return (true);
+  }
+  return (false);
 }
 
 //Set the readings per second

src/SparkFun_Qwiic_Scale_NAU7802_Arduino_Library.h

@@ -153,11 +153,19 @@ typedef enum
   NAU7802_CHANNEL_2 = 1,
 } NAU7802_Channels;
 
+//Calibration state
+typedef enum
+{
+  NAU7802_CAL_SUCCESS = 0,
+  NAU7802_CAL_IN_PROGRESS = 1,
+  NAU7802_CAL_FAILURE = 2,
+} NAU7802_Cal_Status;
+
 class NAU7802
 {
 public:
   NAU7802();                            //Default constructor
-  bool begin(TwoWire &wirePort = Wire); //Check communication and initialize sensor
+  bool begin(TwoWire &wirePort = Wire, bool reset = true); //Check communication and initialize sensor
   bool isConnected();                   //Returns true if device acks at the I2C address
 
   bool available();                           //Returns true if Cycle Ready bit is set (conversion is complete)
@@ -179,7 +187,11 @@ class NAU7802
   bool setSampleRate(uint8_t rate);       //Set the readings per second. 10, 20, 40, 80, and 320 samples per second is available
   bool setChannel(uint8_t channelNumber); //Select between 1 and 2
 
-  bool calibrateAFE(); //Calibrate the analog from end of the NAU7802. Returns true if CAL_ERR bit is 0 (no error)
+  bool calibrateAFE(); //Synchronous calibration of the analog front end of the NAU7802. Returns true if CAL_ERR bit is 0 (no error)
+  void beginCalibrateAFE(); //Begin asynchronous calibration of the analog front end of the NAU7802. Poll for completion with calAFEStatus() or wait with waitForCalibrateAFE().
+  bool waitForCalibrateAFE(uint32_t timeout_ms = 0); //Wait for asynchronous AFE calibration to complete with optional timeout.
+  NAU7802_Cal_Status calAFEStatus(); //Check calibration status.
+
   bool reset();     //Resets all registers to Power Of Defaults
 
   bool powerUp();   //Power up digital and analog sections of scale, ~2mA