![]() Let’s test … yes that looks fine! Of course for our test we use short times, if we want the cycle time to be 1-9 minutes all we have to do is multiply by 60. Here is the code with 48 subtracted: #define SWITCH_PIN 2 // input for toggle switch If we don’t want this, we can add an if statement to test if the input was between 1 and 9, but since nothing goes drastically wrong we keep it simple right now. If an ‘N’ was typed, the cycle time would become 78-48=30. What if the user types anything else than 1-9? Well … then we still get a cycle time, according to the ASCII table – 48. If we subtract 48 from the ASCII code that comes in via the keyboard we should get the correct numbers 1-9. The numbers 0-9 are represented by decimal ASCII values 48-57. You may not have been aware, but all the years that you have been typing on a PC or a smart phone, you have been ‘talking’ ASCII. Hey … that is strange … when we enter 5, the cycle time is 53? Why is that? Well … that’s because numbers and characters are represented as bytes using the American Standard Code for Information Interchange, ASCII for short. If the data types would have been the other way around, then indeed something could go wrong. Night_time = cycle_time random(T_MIN, T_MAX) ĭay_time = cycle_time random(T_MIN, T_MAX) Ĭycle_time is declared as an unsigned int while Serial.read() gives us a byte … will the instruction cycle_time = Serial.read() not give us any trouble like we saw in video 9? No it won’t, since a byte always fits in an int. If (switch_new = LOW) Serial.println("Cycle started") Serial.println("in the field above and press Enter") Ĭycle_time = Serial.read() // multiply by 60 to get minutes Serial.println("To enter a new cycle time, type 1-9") Serial.println("Day/Night cycle system is ready") Unsigned int cycle_time = 1 // 180 = 3 minutes #define T_MAX 5 // maximum random time to add to cycle_time #define T_MIN 1 // minimum random time to add to cycle_time #define LED_PIN A5 // output to LED on switch panel #define LIGHTS_PIN 8 // output to FET or relay module #define SWITCH_PIN 2 // input for toggle switch Let’s first try this with the Serial.read() function, which reads one character at a time. In loop() we add an if statement to check if data is available and if it is, we read it and we print it … that’s it. It’s a bit more complex than serial output, but not by much! The key functions are Serial.available() and Serial.read().In setup() we add new print statements to tell the user how to enter a new cycle time. Serial inputs can be very useful in your Arduino project. ![]() This is a function in the Arduino String class which returns true if the string in question is equal to the parameter string. Here’s a somewhat abstract example on how to do this: Depending on what you send, the Arduino will perform different task. Sending CommandsĪ more usable scenario could be to send commands to the Arduino. In this case we’re waiting for the \n character, which is the newline character that comes at the end of a string sent in the Arduino serial monitor. Here we’ve introduced the readStringUntil() function, which makes it possible to combine all the characters in the sent message into a single Arduino string. ![]() Serial.println("Nice to meet you, " my_name "!") If we send more than one character over serial with this code, the output will look like this:īut what if you want to send more than one character in handle it in a sensible way? No problemo! So when all the bytes of data are read and no new serial data have arrived, the buffer is empty and Serial.available() will return 0. ![]() Serial.read() returns the first (oldest) character in the buffer and removes that byte of data from the buffer. bytes of data) which have arrived in the serial buffer and that are ready to be read. Serial.available() returns the number of characters (i.e. There are two important functions related to the serial input in the code above, and that is Serial.available() and Serial.read(). Press the Send button or the Enter key on your keyboard to send. To send characters over serial from your computer to the Arduino just open the serial monitor and type something in the field next to the Send button. Using serial inputs is not much more complex than serial output. No matter what you decide to use it for, your system reaches a higher level of interactivity. Maybe you want to display text on an LCD display, punch in numbers to controll LEDs, control motor movement with arrow keys or send commands to decide which functions to call. The possibilites with serial inputs are endless. We have rarely written about serial input, however, which is what this post is about. It is also invaluable as a debugging tool. In almost every Arduino tutorial we’ve written we’ve used serial output for either printing text to terminal or plotting values. ![]()
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