The usage of the ANSI function strcat is incorrect. The strcat function expects as second parameter a pointer to
a zero terminated string, and here a pointer to a single char is passed instead.
Actually just noted that the first argument is incorrect too

, the result is probably a 3 byte string (2 char's and a 0 byte), but the dest buffer is only 2 bytes.
So should probably be:
Code:
byte concatenar(char char1, char char2){ char char12[3]; char12[0] = char1; char12[1] = char2; char12[2] = 0; Using atoi should work, although I would not actually use it due to its lack of
error reporting.
Daniel