File content as of revision 1:0007712e84a8:

#include "mbed.h"
#include "modbus.h"
#include "RawSerial.h"

DigitalOut myled(LED1);
RawSerial pc(USBTX, USBRX);
InterruptIn button(USER_BUTTON);
Ticker timebase;

uint32_t Tick = 0;
uint32_t pressedTick = 0; 
uint32_t releasedTick = 0; 

void serial_callback()
{
    uint8_t frame[6];
    uint16_t offset, count;
    uint8_t reg_map;
    
    char ch = pc.getc();
    if (modbus_parser(ch, frame)) {
        offset = (frame[2] << 8) | (frame[3]);
        count = (frame[4] << 8) | (frame[5]);
        reg_map = modbus_check(offset, count);
        modbus_response(reg_map);
    }
}

void pressed_callback()
{
    uint16_t skipCount;
    
    if ((Tick > pressedTick) && (Tick > releasedTick)) {
        skipCount = Tick - releasedTick;
        modbus_update(0x0000, skipCount);
        pressedTick = Tick;
        // printf("Pressed: %d - %d - %d\r\n", pressedTick, releasedTick, skipCount);
    }
}

void released_callback()
{
    uint16_t widthCount;
    
    if ((Tick > pressedTick) && (Tick > releasedTick)) {
        widthCount = Tick - pressedTick;
        modbus_update(0x0001, widthCount);
        releasedTick = Tick;
        // printf("Released: %d - %d - %d\r\n", pressedTick, releasedTick, widthCount);
    }
}

void ticker_callback()
{
    Tick++;
}

int main() {
    // setup code
    pc.attach(&serial_callback);
    
    // 1. button code
    button.rise(&pressed_callback);
    button.fall(&released_callback);
    
    // 2. timer code
    timebase.attach(&ticker_callback, 0.1);
    printf("Starting\n");
    printf("Test: %02X\r\n", modbus_check(0x0000, 0x0001));
    printf("Test: %02X\r\n", modbus_check(0x0001, 0x0001));
    printf("Test: %02X\r\n", modbus_check(0x0000, 0x0002));
    printf("Test: %02X\r\n", modbus_check(0x0000, 0x0003));
    printf("Test: %02X\r\n", modbus_check(0x0001, 0x0002));
    printf("Test: %02X\r\n", modbus_check(0x0002, 0x0002));    
    while(1) {
        // blinking LED
        myled = !myled; 
        wait(2.5);
        printf("Detection: %d - %d\r\n", pressedTick, releasedTick);
        modbus_response(0x01);
        modbus_response(0x02);
        modbus_response(0x03);
    }
}