File content as of revision 0:558eaaae3f2b:

#include "mbed.h"

Serial pc(USBTX, USBRX); // tx, rx
DigitalIn signPin(p21); //Radiation Pulse (Yellow)
DigitalIn noisePin(p22); //Vibration Noise Pulse (White)
Timer t;

const double alpha = 53.032; // cpm = uSv x alpha

int index = 0; //Number of loops
char msg[256] = ""; //Message buffer for serial output

int signCount = 0; //Counter for Radiation Pulse
int noiseCount = 0; //Counter for Noise Pulse

int sON = 0; //Lock flag for Radiation Pulse
int nON = 0; //Lock flag for Noise Puls

double cpm = 0; //Count rate [cpm] of current
double cpmHistory[200]; //History of count rates
int cpmIndex = 0; //Position of current count rate on cpmHistory[]
int cpmIndexPrev = 0; //Flag to prevent duplicative counting

//Timing Settings for Loop Interval
int prevTime = 0;
int currTime = 0;

int totalSec = 0; //Elapsed time of measurement [sec]
int totalHour = 0; //Elapsed time of measurement [hour]

//Time settings for CPM calcuaration
int cpmTimeMSec = 0;
int cpmTimeSec = 0;
int cpmTimeMin = 0;

//String buffers of float values for serial output
char cpmBuff[20];
char uSvBuff[20];
char uSvdBuff[20];

int main() {
    //9600bps
    pc.baud(9600);
    
    //PIN setting for Radiation Pulse
    signPin.mode(PullUp);
    //PIN setting for Noise Pulse
    noisePin.mode(PullUp);

    //CSV-formatting for serial output (substitute , for _)
    pc.printf("hour[h]_sec[s]_count_cpm_uSv/h_uSv/hError");

    //Initialize cpmHistory[]
    for (int i = 0; i < 200; i++) {
        cpmHistory[i] = 0;
    }
    t.start();

    while (1) {
        // Raw data of Radiation Pulse: Not-detected -> High, Detected -> Low
        int sign = signPin;
        // Raw data of Noise Pulse: Not-detected -> Low, Detected -> High
        int noise = noisePin;
        //Radiation Pulse normally keeps low for about 100[usec]
        if (sign == 0 && sON == 0) { //Deactivate Radiation Pulse counting for a while
            sON = 1;
            signCount++;
        } else if (sign == 1 && sON == 1) {
            sON = 0;
        }
        //Output readings to serial port, after 10000 loops
        if (index == 10000) //About 160-170 msec in Arduino Nano(ATmega328)
        {
            //Get current time
            currTime = t.read_ms();
            //No noise detected in 10000 loops
            if (noiseCount == 0) {
                //Shift an array for counting log for each 6 sec.
                if (totalSec % 6 == 0 && cpmIndexPrev != totalSec) {
                    cpmIndexPrev = totalSec;
                    cpmIndex++;

                    if (cpmIndex >= 200) {
                        cpmIndex = 0;
                    }

                    if (cpmHistory[cpmIndex] > 0) {
                        cpm -= cpmHistory[cpmIndex];
                    }
                    cpmHistory[cpmIndex] = 0;
                }

                //Store count log
                cpmHistory[cpmIndex] += signCount;
                //Add number of counts
                cpm += signCount;

                //Get ready time for 10000 loops
                cpmTimeMSec += abs(currTime - prevTime);
                //Transform from msec. to sec. (to prevent overflow)
                if (cpmTimeMSec >= 1000) {
                    cpmTimeMSec -= 1000;
                    //Add measurement time to calcurate cpm readings (max=20min.)
                    if (cpmTimeSec >= 20 * 60) {
                        cpmTimeSec = 20 * 60;
                    } else {
                        cpmTimeSec++;
                    }

                    //Total measurement time
                    totalSec++;
                    //Transform from sec. to hour. (to prevent overflow)
                    if (totalSec >= 3600) {
                        totalSec -= 3600;
                        totalHour++;
                    }
                }

                //Elapsed time of measurement (max=20min.)
                double min = cpmTimeSec / 60.0;
                if (min != 0) {
                    //Calculate cpm, uSv/h and error of uSv/h
                    sprintf(cpmBuff, "%f", cpm / min);
                    sprintf(uSvBuff, "%f", cpm / min / alpha);
                    sprintf(uSvdBuff, "%f", sqrt(cpm) / min / alpha);
                } else {
                    //Devision by zero
                    sprintf(cpmBuff, "%f", 0.0);
                    sprintf(uSvBuff, "%f", 0.0);
                    sprintf(uSvdBuff, "%f", 0.0);
                }

                //Create message for serial port
                sprintf(msg, "%d,%d.%03d,%d,%s,%s,%s",totalHour,totalSec,cpmTimeMSec,signCount,cpmBuff,uSvBuff,uSvdBuff);

                //Send message to serial port
                pc.puts(msg);
                pc.printf("\r\n");
            }
            
            //Initialization for next 10000 loops
            prevTime = currTime;
            signCount = 0;
            noiseCount = 0;
            index = 0;
        }
        index++;
    }
}