Personal practice: serial port interruption and communication

Writing interrupts requires a timer:

1. Set its register TMOD

2. The value of THx and TLx (this is to set the initial value of the timer)

3. Turn on the timer (TRx=1)

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Note: There are two registers in the serial port

SCON (Serial Port Controller) and PCON

4. SCON format: SM0 SM1 SM2 REN TB8 RB8 TI RI

(1) SM0 and SM1 are used to set the serial port working mode: 0, 1, 2, 3, a total of 4 working modes.

(2) SM2 is only used for multi-machine communication control bits in Mode 2 and Mode 3.

(3) REN serial reception enable bit. 0 - Disable reception 1 - Enable reception

(4) TB8: In methods 2 and 3, TB8 is the ninth bit of data to be sent by the transmitter.

(5) RB8: In methods 2 and 3, RB8 is the ninth bit of data received by the receiver, which comes from TB8 of the transmitter.

(6)TI: Transmit interrupt flag. It must be cleared by software before sending. During the sending process, TI remains at zero. After sending a frame of data,

Automatically set to 1 by hardware. If you want to continue sending, you must clear it by software.

(7) RI: Receive interrupt flag. Before receiving, it must be cleared by software. During the receiving process, RI remains at zero. After receiving a frame of data,

Automatically set to 1 by the on-chip hardware. If you need to continue receiving, you must clear it again by software.

Power Control Register (Power Controller)

SMOD bit of PCON: baud rate doubling bit. When calculating the baud rate of serial modes 1, 2, and 3; 0 - do not double; 1 - double.