main.cpp

00001 
00002 // LAB 3 SAMPLE PROGRAM 1
00003 //   Revised for mbed 5
00004 
00005 #include "mbed.h"
00006 
00007 
00008 Ticker tick;                // Ticker for reading analog
00009 AnalogIn ain(A0) ;          // Analog input
00010 DigitalOut led1(D8);   // LED 1
00011 DigitalOut led2(D9);   //LED 2
00012 DigitalOut led3(D10);   //LED 3
00013 DigitalOut led4(D11);   //LED 4
00014 DigitalOut led5(D12);   //LED 5
00015 
00016 DigitalIn b1(PTE1, PullUp); //button
00017 
00018 Thread pollT ; // thread to poll
00019 volatile int pressEvent = 0 ;  // Variabe set by the polling thread
00020 
00021 enum buttonPos { up, down, bounce }; // Button positions
00022 void polling() {
00023     buttonPos pos = up ;
00024     int bcounter = 0 ;
00025     while (true) {
00026         switch (pos) {
00027             case up :
00028                 if (!b1.read()) {    // now down 
00029                     pressEvent = 1 ;  // transition occurred
00030                     pos = down ;
00031                 }
00032                 break ;
00033             case down : 
00034                 if (b1 == 1) { // no longer down
00035                     bcounter = 3 ; // wait four cycles
00036                     pos = bounce ;
00037                 }
00038                 break ;
00039             case bounce :
00040                 if (b1 == 0) { // down again - button has bounced
00041                     pos = down ;   // no event
00042                 } else if (bcounter == 0) {
00043                     pos = up ;     // delay passed - reset to up
00044                 } else {
00045                     bcounter-- ;   // continue waiting
00046                 }
00047                 break ;
00048         }
00049         Thread::wait(30);
00050     }
00051 }
00052 
00053 Serial pc(USBTX, USBRX); // tx, rx, for debugging
00054 
00055 // Message type
00056 typedef struct {
00057   uint16_t analog; /* Analog input value */
00058 } message_t;
00059 
00060 // Mail box
00061 Mail<message_t, 2> mailbox;
00062 
00063 // Function called every 10ms to read ADC
00064 // Low pass filter  
00065 // Every 10th value is sent to mailbox
00066 volatile int samples = 0 ;
00067 volatile uint16_t smoothed = 0 ; 
00068 void readA0() {
00069     smoothed = (smoothed >> 1) + (ain.read_u16() >> 1) ;
00070     samples++ ;
00071     if (samples == 10) {
00072         // send to thread
00073         message_t *mess = mailbox.alloc() ; // may fail but does not block
00074         if (mess) {
00075             mess->analog = smoothed ;
00076             mailbox.put(mess); // fails but does not block if full
00077         }
00078         samples = 0;
00079     }       
00080 }
00081 
00082 // Write voltage digits
00083 //   v  Voltage as scale int, e.g. 3.30 is 330
00084 void vToString(int v, char* s) {    
00085     s[3] = '0' + (v % 10) ;
00086     v = v / 10 ;
00087     s[2] = '0' + (v % 10) ;
00088     v = v / 10 ;
00089     s[0] = '0' + (v % 10) ;
00090 }
00091 
00092 // Main program
00093 //   Initialise variables
00094 //   Attach ISR for ticker
00095 //   Procss messages from mailbox    
00096 int main() {
00097     
00098     
00099     pollT.start(callback(polling));
00100 int firstled;  
00101 int secondled;
00102 int thirdled;
00103 int fourthled;
00104 int fifthled;
00105 volatile int max = 330;  //initial max voltage level required to light up the last LED
00106    
00107     int volts = 0 ;
00108  
00109     int counter = 0 ;
00110     char vstring[] = "X.XX\r\n" ;
00111 
00112     tick.attach_us(callback(&readA0), 10000); // ticks every 10ms
00113     while (true) {
00114         osEvent evt = mailbox.get(); // wait for mail 
00115         if (evt.status == osEventMail) {
00116             message_t* mess = (message_t*)evt.value.p ;
00117             volts = (mess->analog * 330) / 0xffff ;
00118              if (pressEvent) {
00119             pressEvent = 0 ; // clear the event variable
00120             max=volts ;  //set the present voltage as the new maximum voltage to light up the last LED
00121         }
00122             mailbox.free(mess) ;  // free the message space
00123             
00124 firstled = max*2/6; //voltage required to light up the first led
00125 secondled = max*3/6; //voltage required to light up the second led
00126 thirdled = max*4/6;  //voltage required to light up the third led
00127 fourthled = max*5/6;  //voltage required to light up the fourth led
00128 fifthled = max;       //voltage required to light up the fifth led
00129           
00130             if (volts >= firstled) led1 = 1 ; else led1 = 0 ;
00131             if (volts >= secondled) led2 = 1; else led2 = 0;
00132             if (volts >=thirdled) led3 = 1; else led3 = 0;
00133             if (volts >= fourthled) led4 = 1; else led4 = 0;
00134             if (volts >= fifthled) led5 = 1; else led5 = 0;
00135             
00136             vToString(volts, vstring) ;
00137             counter++ ;
00138             if (counter == 10) {  // limit bandwidth of serial
00139                 pc.printf(vstring) ;
00140                 counter = 0 ;
00141             }
00142         }
00143 
00144     }
00145 }