How to remove delay? | 易学教程

问题

I am working on a very important project that needs to have maximum efficiency and speed. Basically I use the serial ports of Arduino to communicate to a SIM900 GSM, but I think this can apply to any other device that is connected to the Serial port of Arduino. The problem is that after each command I send to the SIM900 I put a delay because I don't know how much time it will take to be executed, but sometimes commands can be executed really fast or really slow. My question is: How can I display the output of the SIM900 WITHOUT using the delay but maybe a do {} while; a cycle that checks if something new needs to be displayed? I would appreciate if you guys could help me. Thank You!

Here are some commands I used for the serial communication:

 myGsm.begin(19200);  
 Serial.begin(9600);  
 delay(500);

 myGsm.println("AT+CGATT=1");
 delay(200);



 printSerialData();

 myGsm.println("AT+SAPBR=3,1,\"CONTYPE\",\"GPRS\"");//setting the SAPBR,connection type is GPRS
 delay(1000);
 printSerialData();


 myGsm.println("AT+SAPBR=3,1,\"APN\",\"internet.wind\"");//setting the APN,2nd parameter empty works for all networks 
 delay(5000);
 printSerialData();


 myGsm.println("AT+SAPBR=0,1");
 delay(1000);
printSerialData();

 myGsm.println("AT+SAPBR=1,1");
 delay(10000);
printSerialData();

 myGsm.println("AT+HTTPINIT"); //init the HTTP request
 delay(2000); 
printSerialData();


void printSerialData()
{
 while(myGsm.available()!=0)
 Serial.write(myGsm.read());
}

回答1:

There are several ways to solve your problem. One way is a blocking loop until data was received:

void printSerialData()
{
    //Block until data is received
    while(myGsm.available() <= 0);

    //Get received
    while(myGsm.available() > 0)
    {
        while(myGsm.available() > 0)
        {
            Serial.write(myGsm.read());
        }
        //Give chance to receive more
        delay(10);
    }
}

An alternative way makes use of the fact, that AT commands are typically finalized by \r\n. This means you can try to receive data until the final \n. Make use of readBytesUntil or readStringUntil like:

void printSerialData()
{
    String read = myGsm.readStringUntil('\n');
    Serial.write(read);
}

Don't forget to set a correct timeout by calling setTimeout before.

来源：https://stackoverflow.com/questions/59518216/how-to-remove-delay

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