Resolve issue #4

Author: PaulZC

library.properties

@@ -1,5 +1,5 @@
 name=SparkFun MAX1704x Fuel Gauge Arduino Library
-version=1.0.1
+version=1.0.2
 author=SparkFun Electronics <[email protected]>
 maintainer=SparkFun Electronics <sparkfun.com>
 sentence=Arduino library for the MAX17043/44/48/49 fuel gauges

src/SparkFun_MAX1704x_Fuel_Gauge_Arduino_Library.cpp

@@ -61,19 +61,60 @@ boolean SFE_MAX1704X::begin(TwoWire &wirePort)
   return (true);
 }
 
-//Returns true if device answers on _deviceAddress
+//Returns true if device is present
 boolean SFE_MAX1704X::isConnected(void)
 {
-  _i2cPort->beginTransmission((uint8_t)MAX1704x_ADDRESS);
-  if (_i2cPort->endTransmission() == 0)
+  //Updated to resolve issue #4 Dec 27th 2021
+  //Also avoid using the standard "if device answers on _deviceAddress" test
+  //(https://github.com/sparkfun/Arduino_Apollo3/issues/400#issuecomment-992631994)
+  bool success = false;
+  uint8_t retries = 3;
+  uint16_t version = 0;
+
+  while ((success == false) && (retries > 0))
+  {
+    _i2cPort->beginTransmission(MAX1704x_ADDRESS);
+    _i2cPort->write(MAX17043_VERSION); // Attempt to read the version register
+    _i2cPort->endTransmission(false); // Don't release the bus
+
+    if (_i2cPort->requestFrom(MAX1704x_ADDRESS, 2) == 2) // Attempt to read the version (2 bytes)
+    {
+      uint8_t msb = _i2cPort->read();
+      uint8_t lsb = _i2cPort->read();
+      version = ((uint16_t)msb << 8) | lsb;
+      success = true;
+    }
+    else
+    {
+      retries--;
+      if (_printDebug == true)
+      {
+        _debugPort->println(F("SFE_MAX1704X::isConnected: retrying..."));
+      }
+      delay(50);
+    }
+  }
+
+  if (!success) // Return now if the version could not be read
+  {
+    if (_printDebug == true)
+    {
+        _debugPort->println(F("SFE_MAX1704X::isConnected: failed to detect IC!"));
+    }
+    return (success);
+  }
+
+  //Extra test - but only for MAX17048/9 - see issue #4
+  if (_device >= MAX1704X_MAX17048)
   {
     //Get version should return 0x001_
     //Not a great test but something
-    //Supported on 43/44/48/49
-    if (getVersion() & (1 << 4))
-      return true;
+    //Supported on 48/49
+    if ((version & (1 << 4)) == 0)
+      success = false;
   }
-  return false;
+
+  return (success);
 }
 
 //Enable or disable the printing of debug messages

src/SparkFun_MAX1704x_Fuel_Gauge_Arduino_Library.h

@@ -123,7 +123,7 @@ class SFE_MAX1704X
   // begin() - Initializes the MAX17043.
   boolean begin(TwoWire &wirePort = Wire); //Returns true if module is detected
 
-  //Returns true if device answers on MAX1704x_ADDRESS
+  //Returns true if device is present
   boolean isConnected(void);
 
   // Debug