实验3

代码说明：

说明：  1、单向通信 向甲方连续不断地发送变量a的值，未按键，a=0x0f，按键后根据按键确定a值；并将a的值取反从P0口输出，控制D0、D1、D2、D3相应点亮。乙方接收到数据并偶校验正确后，将接收数据取反从P0口输出，控制D0、D1、D2、D3相应点亮。 2、双向通信 甲方连续不断地发送变量a的值，未按键，a=0x0f，按键后根据按键确定a值；乙方未按键不发送，按键后将乙方按键得到的a*16发送；甲乙双方都将发送数据与接收数据相或后再取反，从P0口输出控制D0—D7相应点亮。 3、间隔发送 未按键，甲方不发送数据，按键后甲方每隔50ms连续发送4个字节：0xff、a、a、a。 乙方只在收到甲方数据0xff后的3个数据并验证相同时，才将接收数据*16发送。 甲乙双方都将发送数据与接收数据相或后，从P0口输出控制D0—D7相应点亮。(1. One-way communication The value of variable a is continuously sent to Party A without key, a = 0x0f. After the key is pressed, the value of a is determined according to the key; and the value of a is output from P0 port to control the corresponding lighting of D0, D1, D2 and D3. After receiving the data and checking it correctly, Party B will output the received data from P0 port and control D0, D1, D2 and D3 to light up accordingly. 2. Two-way communication Party A continuously sends the value of variable a without key, a = 0x0f, and determines a value according to the key after the key; Party B does not send the key without key, and sends the a*16 obtained by the key after the key is pressed; Both parties will send the data to or from the receiving data, and then retrieve the data and control D0-D7 from the P0 port to light up accordingly. 3. Interval Sending Without keys, Party A does not send data. After keys, Party A sends 4 bytes continuously every 50 ms: 0xff, a, a.)