#include "mbed.h"
#include "millis.h"
Serial pc(USBTX, USBRX);

void serial_read(float *V0);

float V1 = 0;


unsigned short size_command;

long _time = 0;


int main()
{
    pc.baud(9600);
    millisStart();
    while(1) {
        serial_read(&V1);
        if (millis() - _time > 1000) {
            _time = millis();
            pc.printf("%f\r\n",V1);
        }
    }
}

void serial_read(float *V0)
{

    if (pc.readable()) {
        size_command=pc.getc();
        char command[size_command];
        for (int i=0; i<size_command; i++)
            command[i]= pc.putc(pc.getc());
        
        sscanf(command, "%f", V0);
        
    }
}

hi, I am writing a code for serial input from the PC to the KL25Z board and convert it to a float number and save to variable V1. it appears that the KL25Z successfully receives and convert the serial string into a floating point number, however it only print once and the value of V1 returns to initial value of 0, May I know the error in the code causing this issue? thank you here's my code <<code title= serial input>> #include "mbed.h" #include "millis.h" Serial pc(USBTX, USBRX); void serial_read(float *V0); float V1 = 0; unsigned short size_command; long _time = 0; int main() { pc.baud(9600); millisStart(); while(1) { serial_read(&V1); if (millis() - _time > 1000) { _time = millis(); pc.printf("%f\r\n",V1); } } } void serial_read(float *V0) { if (pc.readable()) { size_command=pc.getc(); char command[size_command]; for (int i=0; i<size_command; i++) command[i]= pc.putc(pc.getc()); sscanf(command, "%f", V0); } } <</code>> printf stop printing once I sent a serial string to the KL25Z, also the first digit is missing in the first trial. And it does not create a new line as well. {{/media/uploads/conrad2001/serial_V3S6pH3.png}} thank you

Hi Conrad, Since ##size_command## is a run time variable, you can't to use the value to create an array like that ##char command[size_command];##. Instead, you should use ##char* command = malloc(size_command);## and ##free()##. Regards, Desmond