pi@navio-rpi:~$ gcc waveclock.c -Wall -l bcm2835 -o waveclock
waveclock.c: In function ‘wait_for_next_minute’:
waveclock.c:58:5: warning: implicit declaration of function ‘gettimeofday’ [-Wimplicit-function-declaration]
waveclock.c:60:5: warning: format ‘%u’ expects argument of type ‘unsigned int’, but argument 3 has type ‘suseconds_t’ [-Wformat]
waveclock.c:61:5: warning: implicit declaration of function ‘usleep’ [-Wimplicit-function-declaration]
waveclock.c:66:5: warning: format ‘%u’ expects argument of type ‘unsigned int’, but argument 3 has type ‘suseconds_t’ [-Wformat]
waveclock.c: In function ‘main’:
waveclock.c:106:5: warning: implicit declaration of function ‘daemon’ [-Wimplicit-function-declaration]