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The Universal Synchronous and Asynchronous serial Receiver and Transmitter (USART) is a highly flexible serial communication device. The main features are:

通用同步和異步串行接收器和發送器(USART)是一種高度靈活的串行通信設備。 主要特點是：

• Full Duplex Operation (Independent Serial Receive and Transmit Registers)

  全雙工操作(獨立的串行接收和發送寄存器)

• Asynchronous or Synchronous Operation

  異步或同步操作

• Master or Slave Clocked Synchronous Operation

  主或從時鐘同步操作

• High-Resolution Baud Rate Generator

  高分辨率波特率發生器

• Supports Serial Frames with 5, 6, 7, 8, or 9 Data Bits and 1 or 2 Stop Bits

  支持具有5、6、7、8或9個數據位和1或2個停止位的串行幀

• Odd or Even Parity Generation and Parity Check Supported by Hardware

  硬件支持奇偶校驗生成和奇偶校驗

• Data Overrun Detection

  數據溢出檢測

• Framing Error Detection

  幀錯誤檢測

• Noise Filtering Includes False Start Bit Detection and Digital Low Pass Filter

  噪聲過濾包括錯誤的起始位檢測和數字低通濾波器

• Three Separate Interrupts on TX Complete, TX Data Register Empty, and RX Complete

  TX完成，TX數據寄存器為空和RX完成的三個獨立中斷

• Multi-processor Communication Mode

  多處理器通訊模式

• Double Speed Asynchronous Communication Mode

  雙速異步通訊模式

These are some of the features of USART, we would now lean to create a program in which we would use Bluetooth technology to open and close a LED bulb. In our program, we would take a variable X, such that if X=A our bulb will glow and if X=B the bulb will stop glowing.

這些是USART的一些功能 ，我們現在傾向于創建一個程序，在該程序中，我們將使用藍牙技術打開和關閉LED燈泡。 在我們的程序中，我們將使用變量X ，使得如果X = A ，則燈泡將發光，如果X = B，則燈泡將停止發光。

In the similar we can also use a fan instead of LED, then we would be controlling our Fan to start or stop.

同樣，我們也可以使用風扇代替LED，然后控制風扇啟動或停止。

Program:



程序：

</ s> </ s> </ s>

#include <avr/io.h>
void usart_string(char*);
int main(void)
{
char x;
DDRA = 0x01;
UBRRL= 51;
UCSRB= 0x18;
UCSRC= 0x86;
usart_string("Sam");
while(1)
{
while((UCSRA&(1<<RXC))==0);
x=UDR;
if(x=='A')
{
PORTA=0x01;
}
else if(x=='B')
{
PORTA=0x00;
}		
}
}
void usart_string(char*p)
{
while(*p!='\0')
{
UDR=*p;
while((UCSRA&(1<<TXC))==0);
UCSRA|=1<<TXC;
p++;
}
}

Explanation:

說明：

• Write all the header files as written above.

  像上面那樣寫所有的頭文件。

• Take a variable X which will decide whether our bulb will be ON or OFF.

  取一個變量X來決定我們的燈泡是開還是關 。

• DDRA=0x01 indicates that the Led bulb is connected.

  DDRA = 0x01指示LED燈泡已連接。

• UBRRL=51; indicates that the baud rate is set to 9600.

  UBRRL = 51； 表示波特率設置為9600 。

• UCSRB=0x18 means R_x and T_x are enabled.

  UCSRB =為0x18裝置R _X和T _X被啟用。

• The usart_string will print the word written inside it.

  usart_string將打印其中寫入的單詞。

• Inside the while loop, we have written our bulb glowing condition such that when A is received the LED will glow and when B is received the LED bulb will stop glowing.

  在while循環內，我們編寫了燈泡發光條件，以便當接收到A時LED發光，而當接收到B時LED燈泡停止發光。

BAUD RATE

波特率

It is the rate at which the information is processed/transferred to the communication channel.

它是信息被處理/傳輸到通信通道的速率。

Calculation of BAUD RATE

波特率的計算

Where, fOSC is "System Oscillator Clock Frequency".

其中， fOSC是“系統振蕩器時鐘頻率” 。

Simulation:

模擬：

Explanation:

說明：

• Select the following components:

  選擇以下組件：

  1. Atmega16
  2. LED Red
  3. From virtual instruments mode select a VIRTUAL TERMINAL

• Add the components as shown in the figure.

  如圖所示添加組件。

• Double click on ATmega16 and make its speed as 8000000 and upload the hex file in it.

  雙擊ATmega16，使其速度達到8000000，并在其中上傳十六進制文件。

• When we will start the simulation a screen will appear that would be our simulation for a Bluetooth screen.

  當我們開始仿真時，將出現一個屏幕，該屏幕將是我們對藍牙屏幕的仿真。

• Typing A will glow the bulb and typing B will stop the bulb from glowing.

  鍵入A將使燈泡發光，鍵入B將使燈泡停止發光。

翻譯自: https://www.includehelp.com/embedded-system/usart-home-automation.aspx

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