Thanks a lot, Félix. I was concentrated on a big file and did not notice this .
Regards
Alain Hamradio F1CJN

My short exemple prints a number on the screen
But if I include a for next loop , it compiles but does not show the number on the M5 core screen.
If I uncomment the" for next" line, it does not print on the screen . Why ?

#include <M5Stack.h>
#include "M5StackUpdater.h"
float voltage = 2224.33;

void setup() {
M5.begin();
}
void loop() {
//for (int i = 1; i = 10; i++) {}
M5.Lcd.setTextColor(WHITE, BLUE);
M5.Lcd.drawString("Voltage = "+String(voltage)+" mV ",30,40,4);
delay(50);
}