RTCLib parsing

An easier method to write all your 7 segments displays at once (assuming you want hours, minutes and seconds):

char time_str[7];
sprintf( time_str, "%02d%02d%02d", now.hour(), now.minute(), now.second() );

for (uint8_t i = 0; i < 6; i++ )
  matrix.writeDigitNum( i+1, time_str[i] - '0' ); //not sure if the first 7-seg is id 1 but whatever, modify if needed