File content as of revision 2:4348f9a6c179:

// LAB 3 SAMPLE PROGRAM 1
//   Revised for mbed 5

#include "mbed.h"


Ticker tick;                // Ticker for reading analog
AnalogIn ain(A0) ;          // Analog input
DigitalOut led1(D8);   // Red LED
DigitalOut led2(D9);   // Red LED
DigitalOut led3(D10);   // Red LED
DigitalOut led4(D11);   // Red LED
DigitalOut led5(D12);   // Red LED

DigitalIn b1(PTE1,PullUp);

Serial pc(USBTX, USBRX); // tx, rx, for debugging

Thread pollT ; // thread to poll
volatile int pressEvent = 0 ;  // Variabe set by the polling thread
int maxvolt = 330;
int threshold =55;


enum buttonPos { up, down, bounce }; // Button positions
void polling() {
    buttonPos pos = up ;
    int bcounter = 0 ;
    while (true) {
        switch (pos) {
            case up :
                if (!b1.read()) {    // now down 
                    pressEvent = 1 ;  // transition occurred
                    pos = down ;
                }
                break ;
            case down : 
                if (b1 == 1) { // no longer down
                    bcounter = 3 ; // wait four cycles
                    pos = bounce ;
                }
                break ;
            case bounce :
                if (b1 == 0) { // down again - button has bounced
                    pos = down ;   // no event
                } else if (bcounter == 0) {
                    pos = up ;     // delay passed - reset to up
                } else {
                    bcounter-- ;   // continue waiting
                }
                break ;
        }
        Thread::wait(30);
    }
}















// Message type 
typedef struct {
  uint16_t analog; /* Analog input value */
} message_t;

// Mail box
Mail<message_t, 2> mailbox;

// Function called every 10ms to read ADC
// Low pass filter  
// Every 10th value is sent to mailbox
volatile int samples = 0 ;
volatile uint16_t smoothed = 0 ; 
void readA0() {
    smoothed = (smoothed >> 1) + (ain.read_u16() >> 1) ;
    samples++ ;
    if (samples == 10) {
        // send to thread
        message_t *mess = mailbox.alloc() ; // may fail but does not block
        if (mess) {
            mess->analog = smoothed ;
            mailbox.put(mess); // fails but does not block if full
        }
        samples = 0;
    }       
}

// Write voltage digits
//   v  Voltage as scale int, e.g. 3.30 is 330
void vToString(int v, char* s) {    
    s[3] = '0' + (v % 10) ;
    v = v / 10 ;
    s[2] = '0' + (v % 10) ;
    v = v / 10 ;
    s[0] = '0' + (v % 10) ;
}

// Main program
//   Initialise variables
//   Attach ISR for ticker
//   Procss messages from mailbox    
int main() {
    led1 = 0 ; // turn off 
    led2 = 0 ;
    led3 = 0 ;
    led4 = 0 ;
    led5 = 0 ;
    int volts = 0 ;
    //const int threshold = 55 ;
    
    pollT.start(callback(polling));
    
    int counter = 0 ;
    char vstring[] = "X.XX\r\n" ;

    threshold = maxvolt/6;

    tick.attach_us(callback(&readA0), 10000); // ticks every 10ms
    while (true) {
        osEvent evt = mailbox.get(); // wait for mail 
        if (evt.status == osEventMail) {
            message_t* mess = (message_t*)evt.value.p ;
            volts = (mess->analog * 330) / 0xffff ;
            mailbox.free(mess) ;  // free the message space
            if(pressEvent)
            {
               pressEvent=0;
               maxvolt = volts;
               threshold= maxvolt / 6;
               led1 = 1;
                    led2 = 1;
                    led3 = 1;
                    led4 = 1;
                    led5 = 1;
            }             
                
               
                if(volts >=threshold*5 && volts <= threshold*6)
                {
                    led1 = 1;
                    led2 = 1;
                    led3 = 1;
                    led4 = 1;
                    led5 = 1;
                }else
                 if(volts >=threshold*4 && volts <= threshold*5)
                {
                    led1 = 1;
                    led2 = 1;
                    led3 = 1;
                    led4 = 1;
                    led5 = 0;
                }else if(volts>=threshold*3 && volts <= threshold*4)
                {
                    led1 = 1;
                    led2 = 1;
                    led3 = 1;
                    led4 = 0;
                    led5 = 0;
                }else
                if( volts>=threshold*2 && volts <= threshold*3)
                {
                    led1 = 1;
                    led2 = 1;
                    led3 = 0;
                    led4 = 0;
                    led5 = 0;
                }else
                 if( volts >threshold && volts <=threshold*2)
                {
                    led1 = 1;   
                    led2 = 0;
                    led3 = 0;
                    led4 = 0;
                    led5 = 0;
                }
                else if(volts < threshold){
                    led1 = 0 ;
                    led2 = 0 ;
                    led3 = 0 ;
                    led5 = 0 ;
                    led5 = 0 ;
                    }
                    
            vToString(volts, vstring) ;
            counter++ ;
            if (counter == 10) {  // limit bandwidth of serial
                pc.printf(vstring) ;
                counter = 0 ;
            }
        }

    }
}