51 single-chip 16-channel rush answer display in dot matrix Puzhong V2

Completed
Design a quiz answering device with 51 as the core, which can be used by 16 players to participate in the competition.

(1) 16 contestants use 4×4 matrix buttons to answer each button.
(2) The two cases of the host are used for system reset and start respectively.
(3) When the host presses the start button, the LED dot matrix displays the countdown time from 9 to zero, and no one answers, and the buzzer sounds.
(4) When the contestant answers successfully, the LED dot matrix displays the contestant number, and the buzzer emits three beeps at an interval of one second, and the countdown stops. The initial state LED dot matrix displays 0, when the answer is successful, the LED dot matrix displays the player number.

#define KEYS P1  
sbit start_key = P3 ^ 0;
sbit qingl_key = P3 ^ 1;
sbit beep_port = P2 ^ 1;
sbit HC595_SER = P3 ^ 4;
sbit HC595_CLK1 = P3 ^ 6;
sbit HC595_CLK2 = P3 ^ 5;