Hello @wa-berlin you can't. Functions w/o numTimer argument will return the internal number assigned to a specific timer. You don't have direct control about which timer gets which number, but you can keep a record of the number assigned to a given timer to further manipulate it. Below is an example with 2 timers (A and B). Timer A counts up ever 2 seconds, whereas timer B counts up every second and stops at 10. With button A you can enable and disable timer A. With button B you can restart timer B once it has stopped. #include <M5Core2.h> #include <utility/M5Timer.h> M5Timer M5T; int mytimerA = -1; int mytimerB = -1; int mycountA = 0; int mycountB = 0; void myTimerACB(void) { mycountA++; } void myTimerBCB(void) { mycountB++; } void setup() { M5.begin(); M5.Lcd.setTextSize(3); mytimerA = M5T.setInterval(2000, myTimerACB); mytimerB = M5T.setTimer(1000, myTimerBCB, 10); } void loop() { M5.update(); M5T.run(); if(M5.BtnA.wasPressed() == true) { if(M5T.isEnabled(mytimerA) == true) { M5T.disable(mytimerA); } else { M5T.enable(mytimerA); } } if(M5.BtnB.wasPressed() == true) { if(M5T.isEnabled(mytimerB) == false) { M5T.deleteTimer(mytimerB); mycountB = 0; mytimerB = M5T.setTimer(1000, myTimerBCB, 10); } } M5.Lcd.setCursor(0, 0); M5.Lcd.printf("Timer A: %s\n", M5T.isEnabled(mytimerA) ? "enabled " : "disabled"); M5.Lcd.printf("Timer A: %04d", mycountA); M5.Lcd.setCursor(0, 100); M5.Lcd.printf("Timer B: %s\n", M5T.isEnabled(mytimerB) ? "enabled " : "disabled"); M5.Lcd.printf("Timer B: %04d", mycountB); } Good luck! Felix