I am having difficulties when printing any type of variable using the Serial.print(ln) command.

The Serial Monitor becomes inactive after printing for approximately 7 - 15 times.

I currently have the STM32 Blue Pill Board, running Mac OS Mojave and Arduino IDE v 1.8.9

void setup() {
  pinMode(PC13, OUTPUT);


void loop() {
  float raw = analogRead(PA0);
  float voltage = (raw * 3.3) / 4096;
  • isolate the area of the error .... start by changing the print command to Serial.println("voltage"); .... it will print the word "voltage" .... just let it run to see if it also hangs up – jsotola Aug 12 at 14:45

Printing a float should work (at least with an Arduino), but to test if it cannot handle it correctly, I suggest you convert the float to a string (e.g., with the C function ftoa, and print the characters one by one or as a string.

Since this C function is not available on Arduino, use the function implementation of this article, credits to Martin Waller:

char *ftoa(char *buffer, double d, int precision) {

    long wholePart = (long) d;

    // Deposit the whole part of the number.


    // Now work on the faction if we need one.

    if (precision > 0) {

        // We do, so locate the end of the string and insert
        // a decimal point.

        char *endOfString = buffer;
        while (*endOfString != '\0') endOfString++;
        *endOfString++ = '.';

        // Now work on the fraction, be sure to turn any negative
        // values positive.

        if (d < 0) {
            d *= -1;
            wholePart *= -1;

        double fraction = d - wholePart;
        while (precision > 0) {

            // Multipleby ten and pull out the digit.

            fraction *= 10;
            wholePart = (long) fraction;
            *endOfString++ = '0' + wholePart;

            // Update the fraction and move on to the
            // next digit.

            fraction -= wholePart;

        // Terminate the string.

        *endOfString = '\0';

   return buffer;

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