Corrected device mode bug and library init bug.

Device mode has to be an unsigned char because upon first power up the
EEPROM is 0xFF (-1 or 255). The 1" displays are common cathode but with
the PNP/NPN configuration of OpenSegment, it actually inverts the
signals so we need to use common anode to get the library to work.

Author: nseidle

firmware/Serial 7-Segment Display/Serial_7_Segment_Display_Firmware/Serial_7_Segment_Display_Firmware.ino

@@ -40,7 +40,7 @@ SevSeg myDisplay; //Create an instance of the object
 //Global variables
 unsigned int analogValue6 = 0; //These are used in analog meter mode
 unsigned int analogValue7 = 0;
-char deviceMode; //This variable is useds to select which mode the device should be in
+unsigned char deviceMode; // This variable is useds to select which mode the device should be in
 unsigned char commandMode = 0;  // Used to indicate if a commandMode byte has been received
 
 // Struct for circular data buffer data received over UART, SPI and I2C are all sent into a single buffer
@@ -78,13 +78,11 @@ void setup()
 
   interrupts();  // Turn interrupts on, and les' go
 
-  //Preload the display buffer, should only be used during code development
+  //Preload the display buffer with a default
   display.digits[0] = 1;
   display.digits[1] = 2;
   display.digits[2] = 3;
   display.digits[3] = 4;
-  
-  myDisplay.SetBrightness(100); //Set the display to 100% bright
 }
 
 // The display is constantly PWM'd in the loop()

firmware/Serial 7-Segment Display/Serial_7_Segment_Display_Firmware/System_Functions.ino

@@ -126,7 +126,11 @@ void setupDisplay()
 
   int numberOfDigits = 4; //Do you have a 2 or 4 digit display?
 
-  int displayType = COMMON_CATHODE; //SparkFun 1" displays are common cathode
+  //The 1" SparkFun displays are common cathode but because of the PNP and NPN
+  //transistor configuration we are using, we need inverted signals:
+  //1 to turn a digit on, 0 to turn a segment on
+  //This is the same as a common anode setup.
+  int displayType = COMMON_ANODE; 
 
   //Initialize the SevSeg library with all the pins needed for this type of display
   myDisplay.Begin(displayType, numberOfDigits,