Introduction - If you have any usage issues, please Google them yourself
The principle is: the single-chip internal memory set of three bytes of storage clock, minute and second information. Use a timer and software combination one second timer interrupt each generate an interrupt, the second value in memory plus 1 Seconds value of 60, it is clear, and the corresponding sub-byte value plus 1 if the score reach 60, the clear sub-bytes, and when the byte value 1 if the time value to reach 24will be 10 bytes cleared.