Mbed_Python_Control_LPC1768_2_main.txt

// This Project should be built in Mbed online compiler (https://developer.mbed.org/compiler)

#include "mbed.h"

Serial pc(USBTX, USBRX);        // mbed communicates with a host PC through a USB Virtual Serial Port

Ticker      myTick;             // Ticker is used for a recurring interrupt
DigitalOut  mypin(p25);         // GPIO, P2_1
AnalogOut   Aout(p18);          // DAC,  P0_26

#define num_values  200         // is fixed, must be even(!)
float dt;                       // microseconds, the value is read from Serial

float DAC_buf[num_values+1]; // a buffer for DAC values and + 1 for the dt value

// Ticker function, updates DAC values every dt:
void T_function() {
    static int counter = 0;       // Counts number of Ticker calls
    Aout = DAC_buf[counter];     // Analog out: new voltage value from DAC_buffer into the DAC
    if (counter == 0) {   
        mypin = 1;                // Synchronization at t = 0
    } 
    else if (counter == num_values/2) {
        mypin = 0;                // Synchronization at t = T/2
    }
    else if (counter == num_values - 1) { 
        counter = 0;              // Restarting the counter
        return;
    }
    counter++;
}

// Function to parse chars into floats:
float bytesToFloat(char b0, char b1, char b2, char b3){
    float output;
    *((char*)(&output) + 0) = b0;
    *((char*)(&output) + 1) = b1;
    *((char*)(&output) + 2) = b2;
    *((char*)(&output) + 3) = b3;
    return output;
}

int main() { 
    while(1) {
        char    ch_buffer[1024];
        
        // Read data through Serial from the Python script into ch_buffer:
        for (int i=0; i<((num_values+1)*4); i++) { // +1 - for reading the dt value
            ch_buffer[i]=pc.getc();
        }
        // Parse data into floats:    
        int count_j = 1;    
        for (int j=0; j<((num_values+1)*4-3); j+=4) {
            if (j==0) {
                DAC_buf[j]=bytesToFloat(ch_buffer[j], ch_buffer[j+1], ch_buffer[j+2], ch_buffer[j+3]);
            }
            else {
                DAC_buf[j-3*count_j]=bytesToFloat(ch_buffer[j], ch_buffer[j+1], ch_buffer[j+2], ch_buffer[j+3]);
                count_j++;
            }
        }  
        dt = DAC_buf[num_values];               // the last transmitted float is the dt value
        myTick.attach_us(&T_function, dt);      // Ticker calls T_function every dt microseconds       
        }
}