So, I'm currently not at home, thus I can't try it by myself. I'm having an ESP8266 microcontroller and can talk to it via UDP. Everything works fine, but I was wondering if my code (below) actually waits for a client to send data or if it keeps checking. In other words: Is the 'loop()' function called all the time, or once and then waits at 'Udp.parsePacket()' for a client to send data?
Sorry for asking this, since this can be figured out really quick, but I won't have the chance to do so for some time, but I still want to continue writing my code. Thanks in advance.
Code:
#include <WiFiUdp.h>
WiFiUDP Udp
void setup() {
...
}
void loop() {
int packetSize = Udp.parsePacket();
if (packetSize) {
Serial.printf("Received %d bytes from %s, port %d\n",
packetSize, Udp.remoteIP().toString().c_str(), Udp.remotePort());
int len = Udp.read(incomingPacket, 255);
if (len > 0)
{
incomingPacket[len] = 0;
}
Serial.printf("UDP packet contents: %s\n", incomingPacket);
if (strcmp(incomingPacket, "LED") == 0) {
Serial.printf("Turning LED on.");
digitalWrite(0, HIGH);
delay(1000);
Serial.printf("Turning LED off.");
digitalWrite(0, LOW);
}
}
}
The documentation gives no indication that this call is blocking, and in fact has an unconditional delay(10) to stop the loop spinning when there is no packet to parse.
I think we can take this to mean that the call is non-blocking, and you should consider having such a delay too.
In the documentation it says that it returns 0 if no package is available, so it is non-blocking. Otherwise it would always return some positive number.
Related
I've been digging this for around a week and doesn't have any way to solve this one. My Arduino code is working for a while (few times / few days) and then stops all of a sudden. I'm trying to implement a WebClient within the Arduino which sends HTTP GET requests to some other server every time (periodically - every 90 seconds) when a motion had been detected / when motion had stopped.
Below you can find the code. Can anyone assist?
#include <Ethernet2.h>
#include <SPI.h>
byte mac[] = { 0x90, 0xA2, 0xDA, 0x10, 0x73, 0x88 };
IPAddress ip(192,168,20,84);
IPAddress server(192,168,50,93); // Google
IPAddress myDns(8, 8, 8, 8);
EthernetClient client;
//getMovement - sends a GET request when motion is detected
void getMovement() {
client.stop();
if (client.connect(server, 8080)) {
client.println("GET /GetARoomMaven/motion?roomId=1&movement=1");
client.println();
Serial.println("Movement Request Sent");
} else {
Serial.println("connection failed");
}
}
//getNoMovement - sends a GET request when motion had stopped
void getNoMovement() {
client.stop();
if (client.connect(server, 8080)) {
client.println("GET /GetARoomMaven/motion?roomId=1&movement=0");
client.println();
Serial.println("Movement Request Sent");
} else {
Serial.println("connection failed");
}
}
//VARS
//the time we give the sensor to calibrate (10-60 secs according to the datasheet)
int calibrationTime = 10;
//the time when the sensor outputs a low impulse
long unsigned int lowIn;
//the amount of milliseconds the sensor has to be low
//before we assume all motion has stopped
long unsigned int pause = 90000;
//
boolean lockLow = true;
boolean takeLowTime;
int pirPin = 2; //the digital pin connected to the PIR sensor's output
int ledPin = 13;
/////////////////////////////
//SETUP
void setup(){
Serial.begin(9600);
pinMode(pirPin, INPUT);
pinMode(ledPin, OUTPUT);
digitalWrite(pirPin, LOW);
Ethernet.begin(mac);
//give the sensor some time to calibrate
Serial.print("calibrating sensor ");
for(int i = 0; i < calibrationTime; i++){
Serial.print(".");
delay(1000);
}
Serial.println(" done");
Serial.println("SENSOR ACTIVE");
delay(50);
loop();
}
////////////////////////////
//LOOP
void loop(){
if(digitalRead(pirPin) == HIGH){
digitalWrite(ledPin, HIGH); //the led visualizes the sensors output pin state
if(lockLow){
//makes sure we wait for a transition to LOW before any further output is made:
lockLow = false;
Serial.print("motion detected at ");
Serial.print(millis()/1000);
Serial.println(" sec");
getMovement();
}
takeLowTime = true;
}
if(digitalRead(pirPin) == LOW){
digitalWrite(ledPin, LOW); //the led visualizes the sensors output pin state
if(takeLowTime){
lowIn = millis(); //save the time of the transition from high to LOW
takeLowTime = false; //make sure this is only done at the start of a LOW phase
}
//if the sensor is low for more than the given pause,
//we assume that no more motion is going to happen
if(!lockLow && millis() - lowIn > pause){
//makes sure this block of code is only executed again after
//a new motion sequence has been detected
lockLow = true;
Serial.print("motion ended at "); //output
Serial.print((millis() - pause)/1000);
Serial.println(" sec");
getNoMovement();
}
}
}
It's hard to say without a better description of symptoms.
Are the LED still blinking ?
If yes, the socket code seems wrong to me:
void getMovement() {
client.stop();
You must remember that TCP requires connection tracking, so you can't immediately stop a socket, it has to linger a bit for acknowledging packets sent.
If you look at the implementation:
void EthernetClient::stop() {
if (_sock == MAX_SOCK_NUM)
return;
[...]
}
stop() will fail if you have more than MAX_SOCK_NUM (which is 4 on your platform) opened at a time. Can this happen?
In all case, you should avoid as much as possible dynamic allocations, you should have a single function sendMovement(bool detected) that's writing the detected value (getMovement and getNoMovement are the same function, so factorize them). You should re-use the client as much as possible (avoid closing the socket and re-opening it unless you get an error from any socket function). Finally, you might want to set up an interrupt on the digital input pin (with some software debouncing) to avoid polling on it, that would release CPU, and, depending on the configuration, might release more time to process SPI messages.
If the LED are not blinking, try to comment out the SPI related code (EthernetClient's code) and check if it works (in that case, I would check the HW for errors, some of the socket code is busy looping (socket::send does this) that would never finish and stop your loop function from progressing. In that case, if you use JTAG to pause the CPU, it'll be in the client.connect or client.println method.
If it still does not work (LED not blinking with no SPI code), then the issue is likely hardware, check voltage / temperature / JTAG connect to the board to interrupt the CPU to figure out where it's struck.
BTW, if you are doing HTTP, the request is wrong and should be:
GET url HTTP/1.1\r\n
Host: yourserverhost.com\r\n
Connection: Keep-Alive\r\n
\r\n
The part HTTP/1.x after the GET url is absolutely required even for HTTP/1.0. Unless you've written your own server (in that case, there's no need to mimick HTTP), it should not work at all, not even once.
Trying to send serial messages using Arduino Uno and standard IDE. Ran into issue parsing the serial message sent to the device.
See that if I include this line Serial.println("Serial.available() = " + String(Serial.available())); I will be able to read the rest of the message. If this is commented out I will only see the first letter of the message and skip over the rest. Attached image of output that I'm seeing with and without the added line of code.
// the setup routine runs once when you press reset:
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
while (!Serial) {} // wait for serial to be initialized
Serial.println("Setup called. Serial port ready.");
Serial.println("Waiting for time sync message...");
while (!Serial.available()) {}
processSyncMessage();
}
void processSyncMessage() {
// parse first letter of message
char messageHeader = (char) Serial.read();
switch (messageHeader) {
case TIME_HEADER:
// do processing
break;
default:
Serial.println("Unknown message sent with header: " + String(messageHeader));
// must include this line in order to see the entire message sent
// just calling a println or a Serial.available() doesn't work ????
Serial.println("Serial.available() = " + String(Serial.available()));
Serial.println("---start of message");
for (int r = 0; r != -1; r = Serial.read()) {
Serial.print((char) r);
}
Serial.println();
Serial.println("---end of message");
break;
}
}
Missing Buffer
With printout
Is this somehow related to a buffer? Can I flush it somehow with fflush(SOME_SECRET_BUFFER)?
have you tried Serial.readString() to parse the entire missing characters?
Serial data is transmitted and received one character at a time. At 9600 baud, the transmission rate is approximately one character per millisecond.
The code assumes that once the first character has arrived, all of them have. This is not the case. The addition of the println consumes CPU time, and therefore has the effect of adding a delay. This delay allows the rest of the original message to be received.
A receive function with an appropriate timeout for your application is needed here.
I'm developing an application that sends a lot of messages by an UDP connection.
Sometimes some packets were lost and after some tests I conclude that the socket was busy.
Thus I put a tiny sleep between calls to sendto API trying to prevent a new send before the last one ends.
It worked, but I want to use a better approach, like treat a signal or something else which point me that the previous send was done.
Is there anything like that?
I'm using C++ language on a Linux environment.
The below code snippet shows what I'm doing:
#define MAX_SIZE 4096
string long_msg = GetLongMessage();
if (!long_msg.empty()) {
long int to_send = long_msg.size();
while (to_send) {
long int ret = sendto(socket_fd,
&long_msg[long_msg.size() - to_send],
(to_send > MAX_SIZE ? MAX_SIZE : to_send), 0,
reinterpret_cast<struct sockaddr*>(&addr_client),
addr_client_len);
if (ret > 0) {
to_send -= ret;
sleep(10);
} else {
// Log error
}
}
}
Edit: The intent of this question is to know a way to detect if a UDP socket is busy due a previous send call and not discuss TCP vs UDP advantages/disadvantages.
So, I've built a basic QT GUI where I want to establish communication with an Arduino Nano through USB. I send a number through the GUI and the Arduino receives the number and processes it.
The communication works fine when I upload the code to Arduino and right afterwards open the GUI and start the process. However, when I disconnect the Arduino from the USB (or restart my PC - I've tried both) and reconnect it to use it with the GUI, the Arduino behaves like it received nothing.
More specifically, in the first case Serial.available() returns "1" as it receives the number properly, but in the latter case it returns "0", so it does nothing.
I made the code as simple as I could trying to track down the issue and the problem continues.
So here is the main QT GUI code:
depth_ = insertDepthEdit->text().toInt(); // user input from GUI
myThread *mThread;
mThread = new myThread(this, depth_);
connect(mThread, SIGNAL(valueRead(QString)), this, SLOT(onTextChange(QString)));
//valueRead is the signal emitted from Arduino
//onTextChange the function that processes the received string
mThread->start();
mThread->wait(100);
mThread->quit();
The Arduino thread code (also QT):
void myThread::run() {
QSerialPort serial;
serial.setPortName("COM3");
serial.setBaudRate(QSerialPort::Baud9600);
serial.setDataBits(QSerialPort::Data8);
serial.setParity(QSerialPort::NoParity);
serial.setStopBits(QSerialPort::OneStop);
serial.setFlowControl(QSerialPort::NoFlowControl);
serial.open(QIODevice::ReadWrite);
if (serial.isOpen() && serial.isWritable()) {
qDebug() << "Ready to write..." << endl;
QByteArray ba(QString::number(depth_).toStdString().c_str());
qDebug() << ba << endl;
serial.write(ba);
if (serial.bytesToWrite() > 0) {
serial.flush();
if (serial.waitForBytesWritten(1000)) {
qDebug() << "data has been sent" << endl;
}
}
if (serial.flush()) {
qDebug() << "ok" << endl;
}
}
else {
qDebug() << "Error";
}
if (serial.isOpen() && serial.isReadable()) {
qDebug() << "Ready to read..." <<endl;
while (serial.waitForReadyRead(5000)) {
QByteArray inByteArray = serial.readLine();
input_ = QString(inByteArray);
qDebug() << input_;
qDebug() << "ok" << endl;
emit valueRead(input_);
}
}
serial.close();
}
And finally the Arduino code:
int c = 0;
const int ledPin = 13;
void setup() {
Serial.begin(9600);
}
void loop() {
Serial.print(Serial.available());
while (Serial.available() > 0) {
digitalWrite(ledPin, HIGH);
delay(5);
c = Serial.read() - '0';
Serial.flush();
}
delay(1000);
digitalWrite(ledPin, LOW);
delay(500);
}
When I upload the code to Arduino, it functions properly no matter if I close the GUI and restart it. The problem happens only if Arduino loses power, e.g: when I disconnect it from USB or restart the PC.
~~~~~~~~~~~~~~~~~~~~~~~~~~EDIT~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
COM port remains the same after reconnecting and Arduino Rx LED flashes normally when I send data through the GUI.
~~~~~~~~~~~~~~~~~~~~~~~~~~EDIT 2~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
OK, so, I tried using the code from Arduino Serial documentation and the problem remains. When I upload the code the Arduino receives the character properly and turns the LED on, but once I disconnect it and then connect it back, it does nothing, the LED remains low as it never enters "if".
Here's the code I used:
int incomingByte = 0;
void setup() {
Serial.begin(9600);
}
void loop() {
if (Serial.available() > 0) {
digitalWrite(13, HIGH);
incomingByte = Serial.read();
}
}
~~~~~~~~~~~~~~~~~~~~~~EDIT 3~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
So I have the following 3 scenarios:
Use Scenario A:
Upload code
Run GUI
Send data - It receives properly
Disconnect and reconnect
Run GUI again
Send data - RX blinks but Serial.available returns 0
Use Scenario B:
Upload code
Run Brays
Send data - It receives properly
Disconnect and reconnect
Run Brays again
Send data - It receives properly
Use Scenario C (the most interesting) :
Upload code
Run GUI
Send data - It receives properly
Disconnect and reconnect
Run Brays this time
Send data - It receives properly
Run GUI again after Brays
Send data - It receives properly
I also made the QT GUI code as simple as that but the problem persists:
void myThread::run()
{
QSerialPort *serial = new QSerialPort();
serial->setPortName("COM3");
serial->setBaudRate(QSerialPort::Baud9600);
serial->setDataBits(QSerialPort::Data8);
serial->open(QIODevice::WriteOnly);
if (serial->isOpen() && serial->isWritable())
{
QByteArray ba(QString::number(depth_).toStdString().c_str());
serial->write(ba);
serial->flush();
serial->close();
}
delete serial;
}
~~~~~~~~~~~~~~~~~~~~~~EDIT 4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
So after much effort and curiosity, I realized that the source of the problem is not the Arduino code but something related to QT or Windows. I added the delays that Jeff recommended and noticed that each time it functioned properly Rx blinked and LED became high as indicated by the code. However, after reconnecting, the problem still remained but I noticed that, this time, immediately after clicking "Send" to send the characters, the LED blinked for some milliseconds (possibly indicating some error??) and then after the 1 second delay the Rx blinked indicating the receipt of data and LED remained LOW as Serial.available remained 0.
So, what I tried next, was to remove one line of code at a time to see what causes the problem. And I ended up with literally blank Arduino code, just empty setup and loop methods, and the following QT GUI code:
void myThread::run()
{
QSerialPort *serial1 = new QSerialPort();
serial1->setPortName("COM5");
serial1->open(QIODevice::WriteOnly);
serial1->close();
}
To summarize, what happens now is:
Upload code to Arduino
Run GUI
Send data
Nothing happens (normal behaviour)
Disconnect and reconnect Arduino to USB
Run GUI
Send data
Arduino LED momentarily blinks once (possibly indicating some kind of error)
OK, so, after hours of debugging I've found what caused the problem.
The root of it was that after reconnecting the Arduino, each time I called serial.open in QT, Arduino did a reset (indicated by the blink of the LED) and by the time it was after the bootloader stage and was running the code, the main program had already passed the serial.write QT command without receiving the data.
So, what I did to solve the problem was to just add a Sleep(uint(2000)); after serial.open in order to let Arduino finish booting and then start sending data.
Thank you all for your help and immediate answers!
In my experience, the issue is not the code in the Arduino. It is because the serial port gets a different name when it is plugged back in.
For example in Linux, originally the port is /dev/ARD0, but when it is disconnected and plugged back in with connections on ARD0, the new plugin is named /dev/ARD1. (In Windows, it might be COM17 then COM18.)
The only way I know to make it become the original port name is to close everything that is connected to it before plugging in again: Close the Arduino IDE, close all programs which have opened the port, etc.
If you use this example for the Arduino Serial documentation do you receive the chars you send?
int incomingByte = 0; // for incoming serial data
void setup() {
Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
}
void loop() {
// send data only when you receive data:
if (Serial.available() > 0) {
// read the incoming byte:
incomingByte = Serial.read();
// say what you got:
Serial.print("I received: ");
Serial.println(incomingByte, DEC);
}
}
Grasping at straws here, replace my comments below a one second delay. Editing on iPhone messed with the format a little, but I believe you can see my intent.
Edit: Also, I think you should not do serial->close inside your loop. I would also try sending a single character repeatedly until we have that working.
void myThread::run()
{
QSerialPort *serial = new QSerialPort();
serial->setPortName("COM3");
serial->setBaudRate(QSerialPort::Baud9600);
serial->setDataBits(QSerialPort::Data8);
serial->open(QIODevice::WriteOnly);
if (serial->isOpen() && serial->isWritable())
{
QByteArray ba(QString::number(depth_).toStdString().c_str());
serial->write("x");
delay 1 second here
serial->flush();
delay 1 second here
}
serial->close();
delay 1 second here
delete serial;
}
I've run the simple serial program on my Arduino Uno, which just echos whatever you type to it. This works perfectly when run in the Arduino Sketch IDE (v22).
int incomingByte = 0; // for incoming serial data
void setup() {
Serial.begin(115200); // opens serial port, sets data rate
}
void loop() {
// send data only when you receive data:
if (Serial.available() > 0) {
// read the incoming byte:
incomingByte = Serial.read();
// say what you got:
Serial.print("I received: ");
Serial.println(incomingByte, DEC);
}
}
(Code taken from http://arduino.cc/en/Serial/Available)
However, I prefer not to use the Arduino IDE and would rather compile my C++ code with avr-g++, so I wrote this, which should function exactly the same as above:
extern "C" {
#include <avr/io.h>
}
#include <HardwareSerial.h>
extern "C" void __cxa_pure_virtual() { while(1); }
int main (void)
{
int incomingByte = 0;
Serial.begin(115200);
while (1) {
if (Serial.available() > 0) {
incomingByte = Serial.read();
//print as an ASCII character
Serial.print("received: ");
Serial.println(incomingByte, DEC);
}
}
return 1;
}
I compile and run it, but it doesn't work. I never see my text echoed back to me. I tried printing out the value of Serial.available() in the while(1) loop, and it's always zero. Whenever I type on the keyboard, I see the RX LED light up, but nothing happens after that. I can edit my code to successfully call Serial.println() as long as it's outside the Serial.available() conditional.
I've confirmed that my baud rate in my serial software is also set to 115200. And yes, my serial software is pointing to the right serial port.
What am I missing?
Arduino's original glue code looks like this:
#include <WProgram.h>
int main(void)
{
init();
setup();
for (;;)
loop();
return 0;
}
The init() stuff is missing in your code. init() is defined in $ARDUINO_HOME/hardware/arduino/cores/arduino/wiring.c, you can either link against it directly or just copy the code of init() into your code.
You probably have not properly initialized the UART port on the chip. This has to be done manually for microcontrollers, and the Arduino IDE was probably doing it for you. Check the AVR datasheet for your chip, specifically the serial port section.
Found the answer to my own question:
It turns out the HardwareSerial.h library relies on interrupts. This is something that is automagically taken care of for you when building with the Arduino IDE. If you aren't using the Arduino IDE (like me), then you must remember to enable interrupts on your own.
Just #include <avr/interrupt.h>, and call sei(); to turn on interrupts before you try to use the Serial Library.
cheers!