I am trying to input data to the serial monitor. I have been guided by an article in 'circuit basics' called 'how to read user input from arduino. The article gives a complicated example. I designed a simple example. The program waits for me to input a value for x and then reads it when entered and prints out the result. It compiles ok but there is a bug in the program. The program; int x; void setup() { Serial.begin(9600); } void loop() { Serial.print("input value for variable x: "); while (Serial.available() == 0) { } x = Serial.parseInt(); Serial.print("x="); Serial.println(x); } The result; input value for variable x: x=7 input value for variable x: x=0 input value for variable x: The second line x=0 should not be there. The third line waits for another input and then the same thing happens showing x=0 again. Can anybody tell me where the bug is in this program? I never entered a value of x=0.

/* Right Triangle - User Interactive via Serial Terminal M. Ray Burnette 20130125 Arduino Nano 328P target processor Binary sketch size: 5,202 bytes (of a 30,720 byte maximum) */ #include "math.h" // include the Math Library #define BAUD 9600 #define timeoutPeriod 2147483647 // Long var... about 25 days float a; float b; float h; char junk = ' '; void setup() // run once, when the sketch starts { Serial.begin(BAUD); // set up Serial library at 9600 bps Serial.setTimeout(timeoutPeriod); // default is 1 second Serial.println("Let's calculate a hypotenuse, h"); Serial.println(" /|"); Serial.println(" / |"); Serial.println(" / |"); Serial.println(" h / |"); Serial.println(" / b|"); Serial.println(" / |"); Serial.println(" / |"); Serial.println(" /________a_____|"); Serial.println(""); Serial.println(""); } void loop() { Serial.println("Enter value for leg 'a', Press ENTER"); while (Serial.available() == 0) ; // Wait here until input buffer has a character { //Side 1 a = Serial.parseFloat(); // new command in 1.0 forward Serial.print("a = "); Serial.println(a, DEC); while (Serial.available() > 0) // .parseFloat() can leave non-numeric characters { junk = Serial.read() ; } // clear the keyboard buffer } Serial.println("Enter value for leg 'b', Press ENTER"); while (Serial.available() == 0) ; { //Side 2 b = Serial.parseFloat(); Serial.print("b = "); Serial.println(b, DEC); while (Serial.available() > 0) { junk = Serial.read() ; } h = sqrt ( a*a + b*b ); Serial.print("hypotenuse = "); Serial.println(h, DEC); Serial.println(); } } Much more complex: Don't Cross The Streams (FP scientific calculator serial co-processor) - Community / Exhibition / Gallery - Arduino Forum

[image] petercl14: The second line x=0 should not be there. This is most likely happening because you have Carriage Return & New Line line ending selected in the monitor. parseInt looks for line endings ... it finds 2... thinks there must be 2 integers. Select either CR or NL... and your problem should go away. [image]

Too complicated for me. I prefer simple, understandable programming. Have a look at the Circuit Basics example which is much simpler. Although they could have made it a lot simpler by leaving out all those sensor readings. All I needed was a program that inputted a number.

Sorry red car. Don't follow what you mean. Where do I add this CR or NL into my program or is it a keyboard thing? How have I had Carriage Return & New Line line ending selected in the monitor?

In the serial monitor... I showed a screen shot of it above. At the bottom of the monitor window ... the left drop down box "Both NL & CR" in the screen shot. [image]

Thanks red car. I missed that in your first posting. I have to pick one or the other but not both. Have not looked at it yet but am now going to. It must be a default thing if both are selected.

Yep, either CR or NL, but not NL & CR. If you don't then you need to handle the extra line ending when reading in your code. Changing in the monitor is easier.

Hi red car, Had several problems. The CR , NL buttons had been hidden from view by the bottom taskbar. Hid the taskbar then could view them. Of all 4 selections only 'no line ending' fixed the bug. All good now. Thanks very much for the help.

[image] petercl14: All good now. Good to hear.. and yes, my mistake "No line ending" is recommended in this case... I was thinking of a slightly different issue.

Input data to serial monitor

Projects Programming

groundFungus December 23, 2022, 3:03am 5

The setial input basics tutorial may be of interest.

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Input data to serial monitor

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