I am trying to get a string containing the uptime of my Arduino. I'm using this code:
long t = millis() / 1000;
word h = t / 3600;
byte m = (t / 60) % 60;
byte s = t % 60;
String uptime = h/10 + h%10 + m/10 + m%10 + s/10 + s%10;
But I get 'invalid conversion' errors. Should I do this with sprintf or something?