Attempt to 'fix' issue #26. No good breakthroughs yet.

Ex 14 DebugOutput is still freezing at odd times. The increase of time between I2C checks to 100ms helps a little but doesn't fix the random freeze-for-a-few-seconds problem.

Author: nseidle

Diff for: src/SparkFun_Ublox_Arduino_Library.cpp

@@ -208,6 +208,7 @@ boolean SFE_UBLOX_GPS::checkUblox()
 }
 
 //Polls I2C for data, passing any new bytes to process()
+//Returns true if new bytes are available
 boolean SFE_UBLOX_GPS::checkUbloxI2C()
 {
   if (millis() - lastCheck >= I2C_POLLING_WAIT_MS)
@@ -224,14 +225,20 @@ boolean SFE_UBLOX_GPS::checkUbloxI2C()
     {
       uint8_t msb = _i2cPort->read();
       uint8_t lsb = _i2cPort->read();
+      if (lsb == 0xFF)
+      {
+        debugPrintln("No bytes available");
+        lastCheck = millis(); //Put off checking to avoid I2C bus traffic
+        return (false);
+      }
       bytesAvailable = (uint16_t)msb << 8 | lsb;
     }
 
     if (bytesAvailable == 0)
     {
       debugPrintln("Zero bytes available");
       lastCheck = millis(); //Put off checking to avoid I2C bus traffic
-      return (true);
+      return (false);
     }
 
     while (bytesAvailable)

Diff for: src/SparkFun_Ublox_Arduino_Library.h

@@ -422,7 +422,7 @@ class SFE_UBLOX_GPS
 	ubxPacket packetAck = {0, 0, 0, 0, 0, payloadAck, 0, 0, false};
 	ubxPacket packetCfg = {0, 0, 0, 0, 0, payloadCfg, 0, 0, false};
 
-	const uint8_t I2C_POLLING_WAIT_MS = 25; //Limit checking of new characters to every X ms
+	const uint8_t I2C_POLLING_WAIT_MS = 100; //Limit checking of new characters to every X ms
 	unsigned long lastCheck = 0;
 	boolean autoPVT = false;	//Whether autoPVT is enabled or not
 	boolean commandAck = false; //This goes true after we send a command and it's ack'd