Added brightness control into the library.

nseidle · nseidle · commit f71bdde7a311 · 2012-11-01T23:45:23.000-06:00
By setting a frame size of about 3000us, the library now varies the
amount of time the display is on and off. This means you only need to
call .DisplayString over and over again.
diff --git a/SevSeg/Example/SevSeg_Counter/SevSeg_Counter.ino b/SevSeg/Example/SevSeg_Counter/SevSeg_Counter.ino
@@ -1,6 +1,6 @@
 /*
  7-23-2012
- Spark Fun Electronics
+   Spark Fun Electronics
  Nathan Seidle
  
  This code is originally based Dean Reading's Library deanreading@hotmail.com
diff --git a/SevSeg/SevSeg.cpp b/SevSeg/SevSeg.cpp
@@ -54,7 +54,9 @@
  Any number between -999 and 9999 can be displayed. 
  To move the decimal place one digit to the left, use '1' as the second
  argument. For example, if you wanted to display '3.141' you would call 
- myDisplay.DisplayNumber(3141, 1);
+ myDisplay.DisplayString("3141", 1, 250);
+ The last argument (250) is the amount of time the display will be on in microseconds.
+ Used in conjunction with
  
  */
 
@@ -144,7 +146,8 @@ void SevSeg::Begin(boolean mode_in, byte numOfDigits,
 //Given a string such as "-A32", we display -A32
 //Each digit is displayed for ~2000us, and cycles through the 4 digits
 //After running through the 4 numbers, the display is turned off
-void SevSeg::DisplayString(char* toDisplay, byte DecPlace){
+//Will turn the display on for a given amount of time - this helps control brightness
+void SevSeg::DisplayString(char* toDisplay, byte DecPlace, unsigned int brightnessLevel){
 
 	//For the purpose of this code, digit = 1 is the left most digit, digit = 4 is the right most digit
 
@@ -183,8 +186,9 @@ void SevSeg::DisplayString(char* toDisplay, byte DecPlace){
 		
 		//Service the decimal point
 		if(DecPlace == digit) digitalWrite(segmentDP, SegOn);
-
-		delayMicroseconds(2000); //Display this digit for a fraction of a second (between 1us and 5000us, 500-2000 is pretty good)
+		
+		delayMicroseconds(brightnessLevel + 1); //Display this digit for a fraction of a second (between 1us and 5000us, 500-2000 is pretty good)
+		//The + 1 is a bit of a hack but it removes the possible zero display (0 causes display to become bright and flickery)
 		//If you set this too long, the display will start to flicker. Set it to 25000 for some fun.
 
 		//Turn off all segments
@@ -215,6 +219,10 @@ void SevSeg::DisplayString(char* toDisplay, byte DecPlace){
 
 			//This only currently works for 4 digits
 		}
+
+		// The display is on for microSeconds(brightnessLevel + 1), now turn off for the remainder of the framePeriod
+		delayMicroseconds(FRAMEPERIOD - brightnessLevel + 1); //the +1 is a hack so that we can never have a delayMicroseconds(0), causes display to flicker 
+		
 	}
   
 }
diff --git a/SevSeg/SevSeg.h b/SevSeg/SevSeg.h
@@ -15,6 +15,17 @@
 
 #define BLANK 16 //Special character that turns off all segments (we chose 16 as it is the first spot that has this)
 
+// framePeriod controls the length of time between display refreshes
+// It's also closely linked to the brightness setting
+#define FRAMEPERIOD 3000 
+//Total amount of time (in microseconds) for the display frame. 1,000us is roughly 1000Hz update rate
+//A framePeriod of:
+//5000 is flickery
+//3000 has good low brightness vs full brightness
+//2000 works well
+//500 seems like the low brightness is pretty bright, not great
+
+
 //This is the combined array that contains all the segment configurations for many different characters and symbols
 const unsigned char characterArray[128][7] = {
 // A  B  C  D  E  F  G  Segments
@@ -155,7 +166,7 @@ class SevSeg {
   SevSeg();
 
   //Public Functions
-  void DisplayString(char*, byte);
+  void DisplayString(char*, byte, unsigned int);
 //  void NewNumber(int number_in, byte DecPlace_in); 
   void Begin(boolean mode_in, byte numOfDigits, byte digit1, byte digit2, byte digit3, byte digit4, byte segment1, byte segment2, byte segment3, byte segment4, byte segment5, byte segment6, byte segment7, byte segmentDP);
 
