File content as of revision 2:24a06c840c25:

// 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(PTA12);
DigitalOut led2(PTA4);
DigitalOut led3(PTA5);
DigitalOut led4(PTC8);
DigitalOut led5(PTC9);
Serial pc(USBTX, USBRX); // tx, rx, for debugging

DigitalIn b1(PTD0, PullUp);

volatile int pressEvent = 0 ;  // Variabe set by the polling thread

enum buttonPos { up, down, bounce }; // Button positions
void polling()
{
    buttonPos pos = up ;
    int bcounter = 0 ;

    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 ;

    }
}

// 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()
{
    polling();
    smoothed = (smoothed >> 1) + (ain.read_u16() >> 1) ; // divided by 2 - reduce the signal noise
    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 = 1 ; // turn off
    int volts = 0 ;
    int threshold = 100 ; // 1 vol
    int counter = 0 ;
    char vstring[] = "X.XX\r\n" ;

    tick.attach_us(callback(&readA0), 10000); // ticks every 10ms -> 10000 micro second


    while (true) {
        osEvent evt = mailbox.get(); // wait for mail



        // every 100 ms this loop operates
        if (evt.status == osEventMail) {
            message_t* mess = (message_t*)evt.value.p ;
            volts = (mess->analog * 330) / 0xffff ; // 2 ^ 16
            
            if (pressEvent) {
            pressEvent = 0 ; // clear the event variable
            threshold = volts;

             }
            
            mailbox.free(mess) ;  // free the message space
            if(volts < (threshold / 6)) {
                led1 = 0;
                led2 = 0;
                led3 = 0;
                led4 = 0;
                led5 = 0;
            }
            if((volts > (threshold * 1/ 6))&&(volts < (threshold * 2/ 6))) {
                led1 = 1;
                led2 = 0;
                led3 = 0;
                led4 = 0;
                led5 = 0;
            }
            if((volts > (threshold * 2/ 6))&&(volts < (threshold * 3/ 6))) {
                led1 = 1;
                led2 = 1;
                led3 = 0;
                led4 = 0;
                led5 = 0;
            }
            if((volts > (threshold * 3/ 6))&&(volts < (threshold * 4/ 6))) {
                led1 = 1;
                led2 = 1;
                led3 = 1;
                led4 = 0;
                led5 = 0;
            }
            if((volts > (threshold * 4/ 6))&&(volts < (threshold * 5/ 6))) {
                led1 = 1;
                led2 = 1;
                led3 = 1;
                led4 = 1;
                led5 = 0;
            }
            if(volts > (threshold * 5/ 6)) {
                led1 = 1;
                led2 = 1;
                led3 = 1;
                led4 = 1;
                led5 = 1;
            }
            vToString(volts, vstring) ;
            counter++ ;

            // every 1 s this loop will operate
            if (counter == 10) {  // limit bandwidth of serial
                pc.printf(vstring) ;
                counter = 0 ;
            }
        }

    }
}