If you need to use Serial.parseInt in a situation where empty buffers (null), line feeds or other unexpected characters might come through, it should just be a matter of filtering the input better than I did in the example code. The code in the question assumed that the only input would be integers coming over the serial connection, which is actually a pretty fragile assumption. Therefore Serial.parseInt() returns 0 and the code that follows proceeds with that value. we are looking at an empty buffer that finally times out. So Serial.available() is true after the line feed character enters the buffer, but there is no "valid digit" according to Serial.parseInt(). When the time-out (see tTimeout()) occurs, 0 is returned Parsing stops when no characters have been read for a configurable.Initial characters that are not digits or a minus sign, are skipped.ParseInt() inherits from the Stream utility class. Looks for the next valid integer in the incoming serial stream. Here is an explanation from the Serial part of the Arduino Language Reference: It took me a little while to figure out why. But then Serial.parseInt() chewed on that line feed for a moment (there was a slight but noticeable delay), then fed the numeral 0 to my function. First of all, the Serial Monitor sent the number I typed in, followed moments later by ascii 10, which is the line feed character. I debugged by printing the ascii values that were making it through my if-statement. One thing I did not expect is how the Arduino software interprets the newline. Without the additional character being inserted by the Serial Monitor, everything behaves as expected. Actually, the solution is simply to select "no line ending" in the Arduino Serial Monitor's dropdown option (by default, I guess mine was set to "New Line"). Obtiene el nmero de bytes (caracteres) disponibles para su lectura desde el puerto serie. It turns out there is no mysterious problem with the hardware or the code, as I first suspected there was. The result is that my throttle is being set to the value I enter, and then almost immediately re-set to 0. I only expect one value to go through this way. By that I mean, it is true when I type in a value such as 125, and a moment later it will be 'true' again when I have typed in nothing additional. Anyway, the statement if (Serial.available()) succeeds twice. Much of it is from publicly available examples. Please note this code is not my final masterpiece. Serial.println(s_action_error + temp_throttle) Serial.println(s_throttle_read + throttle) Serial.println(s_throttle_set + throttle) If (temp_throttle >= 0 & temp_throttle <= 180) Serial.println("Throttle value: 0 through 255, or 999 to read current value.") String s_action_error = "No action known for input value: " String s_throttle_read = "Reading throttle value: " String s_throttle_set = "Throttle set to: " Int throttle = 0 // servo position indicates throttle position. The second time, it sets the throttle value in my code to 0. MySerial.When I test Serial.available() or Serial.available() > 0 in my loop() function, it appears to return true twice each time I enter serial data. Serial.println("MySerial is NOT available") MySerial.println("mySerial is available") SoftwareSerial mySerial(inpt,outpt) // RX, TX The following is the code I've been working on: #include I've been troubleshooting for nearly a week, and am completely stumped. When I run other Arduino sketches, they work just fine. The problem is that every time I run my code, Serial.available() returns 0. I'm trying get my PC to communicate with my Arduino, via the RS232 TTL UART port, in order to eventually be able to send data from my PC to the Arduino. Here's the datasheet for the Arduino, and the datasheet for the Rs232 shield. I'm an Arduino newbie, with a Mega 2560 R3, a RS232 shield V2, and a USB/RS232 cable.
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