Task2Keypad.cpp

00001 #include "Task2Keypad.h"
00002 
00003 void KeypadTask(void)
00004 {/**
00005  *\brief TASK 2, Keypad management. 
00006          It uses just one ADC port. Five keys switch a 5 resistor ladder
00007          obtaining a unique voltage for each key, with a priority that 
00008          depends from the position of the resistor in the ladder.
00009          This function makes an average of 50 analog values (50ms) before 
00010          confirming the output, to filter out some noise and debounce keys
00011  */
00012 
00013     static float KeypadAcc;         // accumulator to compute average
00014     static float KeypadPrev;        // previous value to compute variation 
00015     static int KeypadCount;         // all samples number
00016     static int KeypadRealCount;     // valid samples only
00017     float KeypadVal;  
00018     static char KeyPrev='-';
00019     
00020     os.SetTimer(KEYPAD_TMR, 1, 1);
00021     while(1)
00022     {
00023         os.WaitEvent(KEYPAD_EVT);
00024         float InValue = KeypadIn.read();
00025         if ((InValue > 0.3) && (abs(InValue - KeypadPrev) < 0.1))
00026         {// makes the average only of the values above a threshold 
00027          // and within an almost stable range
00028             KeypadAcc+=InValue;
00029             KeypadRealCount++;
00030         }
00031             
00032         KeypadCount++;
00033         KeypadPrev=InValue;
00034     
00035         if (KeypadCount >=50)
00036         {
00037             if(KeypadRealCount > 25)
00038             {
00039                 KeypadVal=KeypadAcc/KeypadRealCount;
00040             }
00041             else
00042             {// not enough values to average
00043     
00044                 KeypadVal=0;
00045             }
00046            
00047             KeypadAcc=0;
00048             KeypadCount=0;
00049             KeypadRealCount=0;
00050          
00051             if(KeypadVal <0.15)
00052             {
00053                 Key='-';
00054             }
00055             else if(KeypadVal>=0.3 && KeypadVal<0.35)
00056             {
00057                 Key='E';
00058             }
00059             else if(KeypadVal>=0.42 && KeypadVal<0.50)
00060             {
00061                 Key='v';
00062             }
00063             else if(KeypadVal>=0.60 && KeypadVal<0.65)
00064             {
00065                 Key='^';
00066             }
00067             else if(KeypadVal>=0.74 && KeypadVal<0.78)
00068             {
00069                 Key='>';
00070             }        
00071             else if(KeypadVal>=0.85)
00072             {
00073                 Key='<';
00074             }
00075             
00076             if (Key!='-' && Key!=KeyPrev)
00077             {// switch on the LCD backlight if key pressed
00078                 os.SetEvent(LCD_LIGHT_DIM_ON_EVT, LCD_LIGHT_DIM_TASK);
00079             }
00080             KeyPrev=Key;
00081             switch (Key)
00082             {
00083                 case '^':
00084                     Menu=0;
00085                 break;
00086      
00087                 case '>':
00088                     Menu=1;
00089                 break;           
00090      
00091                 case 'v':
00092                     Menu=2;
00093                 break;
00094                 
00095                 case '<':
00096                     Menu=3;
00097                 break;
00098                 
00099                 case 'E':
00100                     Menu=4;
00101                 break;
00102             }     
00103        }
00104    } 
00105 }