Adding bar drawing for graphing sensor data.

Bar.cpp

@@ -0,0 +1,57 @@
+#include "Arduino.h"
+#include "Bar.h"
+
+Bar::Bar()
+{
+}
+
+/* 
+ Set up custom characters
+ on the LCD to allow display of bar graphs
+ */
+void Bar::init(LiquidCrystal lcd){
+  byte barChar[8] = {
+    B10000,
+    B10000,
+    B10000,
+    B10000,
+    B10000,
+    B10000,
+    B10000,
+    B10000
+  };
+
+  for(int i = 0; i < 4; i++){
+    lcd.createChar(i, barChar);
+    byte next = (barChar[0] >> 1) | B10000;
+    for(int i = 0; i < 8; i++){
+      barChar[i] = next;
+    }
+  }
+}
+
+void Bar::draw(LiquidCrystal lcd, byte startChar, byte endChar, byte row, int maxValue, int value){
+  char _charForCols[] = {0x20, 0x00, 0x01, 0x02, 0x03, 0x04};
+  byte barWidthChars = endChar - (startChar - 1);
+
+  byte numCols = barWidthChars * 5 ;// 5 cols per char
+  float colsPerStep = (float) numCols / (float) maxValue;
+  numCols = (float)value * colsPerStep;
+
+  byte wholeBlocks = numCols / 5;
+  char lastChar = _charForCols[numCols % 5];
+
+  lcd.setCursor(startChar, row);
+
+  //write out whole blocks
+  for(byte i = 0; i < wholeBlocks; i++){
+    lcd.write(0xff);
+  }
+  lcd.write(lastChar);
+  if(wholeBlocks < (barWidthChars - 1)){
+    for(byte i = wholeBlocks + 2; i <= barWidthChars; i++){
+      lcd.write(0x20);
+    }
+  }
+}
+

Bar.h

@@ -0,0 +1,17 @@
+#ifndef Bar_h
+#define Bar_h
+
+#include "Arduino.h"
+#include <LiquidCrystal.h>
+
+class Bar
+{
+  public:
+    Bar();
+    void draw(LiquidCrystal lcd, byte startChar, byte endChar, byte row, int maxValue, int value);
+    void init(LiquidCrystal lcd);
+  private:
+    char _charForCols[];
+};
+
+#endif