I have the following code which I am trying to run, however the wait_for_connection() appears to be being run before the preceding 2 lines, and I can't seem to understand why? I really need the two preceding lines to be run before the wait_for_connection() function is called. Even if I enter a sleep(1) before calling the wait_for_connection() function, it is still run before the preceding lines.
My code is as follows:
void wait_for_connection() {
for (int i = 0; i < 10; i++) {
g_print("Checking server...\n");
if (connected == 1) {
g_print("Connected to: %s", selectedServerStr);
break;
}
sleep(1);
}
}
int connect_server(GtkButton *button, gpointer user_data) {
.......
if (gtk_tree_selection_get_selected(GTK_TREE_SELECTION(selectedServer), &model, &iter)) {
path = gtk_tree_model_get_path(model, &iter);
serverIndex = *gtk_tree_path_get_indices(path);
g_print("Selected Server IP: %s\n", serverIPArray[serverIndex][0]);
gtk_widget_set_sensitive(serverList, FALSE); // These 2 lines needs to be run first
append_to_log("Attemping connection, please wait...", 1);
wait_for_connection(); // This is where the error lies, this runs before the above 2 lines
return 1;
} else {
gtk_widget_set_name(serverBox, "fieldsError");
g_print("No server selected: Aborting...\n");
return -1;
}
}
The line gtk_widget_set_sensitive() is used to disable user interaction of a selection widget, however this doesn't seem to happen until after the wait_for_connection() function has finished printing "Checking server..." 10 times. The value connected is 0, so currently the function just print "Checking server..." 10 times.
Does anyone have any idea as to what may be happening? Any help would be greatly appreciated, thanks.
GUI applications on almost all platforms are event-driven. They need their event-handling functions to execute at regular interval, or the user-interface will seem unresponsive and maybe even seem like it locks up or nothing is happening.
In your wait_for_connection you have a loop which can iterate up to ten times, and each iteration you will do sleep(1) which sleeps a whole second. While this loop is iterating and sleeping, the event-handling will not happen, and as mentioned that will make it seem like your user-interface is unresponsive and doesn't do anything.
You need to modify your code to be event-driven as well, so the "connection" status will be sent as an event that you can handle, or somehow make the polling asynchronous so it happens in parallel to the event-handling.
Related
We have several tasks running on an STM32 MCU. In the main.c file we call all the init functions for the various threads. Currently there is one renewing xTimer to trigger a periodic callback (which, at present, does nothing except print a message that it was called). Declarations as follows, outside any function:
TimerHandle_t xMotorTimer;
StaticTimer_t xMotorTimerBuffer;
EventGroupHandle_t MotorEventGroupHandle;
In the init function for the thread:
xMotorTimer = xTimerCreateStatic("MotorTimer",
xTimerPeriod,
uxAutoReload,
( void * ) 0,
MotorTimerCallback,
&xMotorTimerBuffer);
xTimerStart(xMotorTimer, 100);
One thread starts an infinite loop that pauses on an xEventGroupWaitBits() to determine whether to enter an inner loop, which is then governed by its own state:
DeclareTask(MotorThread)
{
bool done = false;
EventBits_t event;
for (;;)
{
Packet * pkt = NULL;
event = xEventGroupWaitBits( MotorEventGroupHandle,
EVT_MOTOR_START | EVT_MOTOR_STOP, // EventBits_t uxBitsToWaitFor
pdTRUE, // BaseType_t xClearOnExit
pdFALSE, // BaseType_t xWaitForAllBits,
portMAX_DELAY //TickType_t xTicksToWait
);
if (event & EVT_MOTOR_STOP)
{
MotorStop(true);
}
if (event & EVT_MOTOR_START)
{
EnableMotor(MOTOR_ALL);
done = false;
while (!done && !abortTest)
{
xQueueReceive(motorQueue, &pkt, portMAX_DELAY);
if (pkt == NULL)
{
done = true;
} else {
done = MotorExecCmd(pkt);
done = ( uxQueueMessagesWaiting(motorQueue) == ( UBaseType_t ) 0);
FreePacket(pkt);
}
}
}
}
}
xEventGroupWaitBits() fires successfully once, the inner loop enters, then exits when the program state meets the expected conditions. The outer loop repeats as it should, but when it arrives again at the xEventGroupWaitBits() call, it crashes almost instantly. In fact, it crashes a few lines down into the wait function, at a call to uxTaskResetEventItemValue(). I can't even step the debugger into the function, as if calling a bad address. But if I check the disassembly, the memory address for the BL instruction hasn't changed since the previous loop, and that address is valid. The expected function is actually there.
I can prevent this chain of events happening altogether by not calling that xTimerStart() and leaving everything else as-is. Everything runs just fine, so it's definitely not xEventGroupWaitBits() (or at least not just that). We tried switching to xEventGroupGetBits() and adding a short osDelay to the loop just as an experiment. That also froze the whole system.
So, main question. Are we doing something FreeRTOS is not meant to do here, using xEventGroupWaitBits() with xTimers running? Or is there supposed to be something between xEventGroupWaitBits() calls, possibly some kind of state reset that we've overlooked? Reviewing the docs, I can't see it, but I could have missed a detail. The
Well, I certainly should go to python since I did several functions of this type, keyboard event and mouse event, but decide to try to learn the windows api.
My goal is to know when button 1 of the mouse is pressed.
I created this file in a very beginner way, it returns in mouseData only 0.
The curious thing is that whenever I run it, it flashes my monitor at short intervals in blinks, but between 1 second with it off. Very strange that, execution is not viable.
Could someone help me understand and try to execute to see if it is only here.
Code:
int main()
{
DWORD mouseData = 0;
MOUSEINPUT tagMouse;
tagMouse.dx = 0;
tagMouse.dy = 0;
tagMouse.mouseData = mouseData;
tagMouse.dwFlags = MOUSEEVENTF_XDOWN;
tagMouse.dwExtraInfo = 0;
INPUT tagInput;
tagInput.type = INPUT_MOUSE;
tagInput.mi = tagMouse;
while (true) {
if (GetAsyncKeyState(VK_DELETE)) break;
SendInput(1, &tagInput, sizeof(INPUT));
printf("KEYWORD: %d\n", mouseData);
Sleep(500);
}
system("pause");
return 0;
}
I can reproduce your reported 'symptoms' - and the effect is really brutal!
Now, while I cannot offer a full explanation, I can offer a fix! You have an uninitialized field in your tagMouse structure (the time member, which is a time-stamp used by the system). Setting this to zero (which tells the system to generate its own time-stamp) fixes the problem. So, just add this line to your other initializer statements:
//...
tagMouse.dwExtraInfo = 0;
tagMouse.time = 0; // Adding this line fixes it!
//...
Note: I, too, would appreciate a fuller explanation; however, an uninitialized field, to me, smells like undefined behaviour! I have tried a variety of other values (i.e. not zero) for the time field but haven't yet found one that works.
The discussion here on devblogs may help. This quote seems relevant:
And who knows what sort of havoc that will create if a program checks
the timestamps and notices that they are either from the future or
have traveled back in time.
I'm making a GTK+3 application in C and I want a spinner to show when the program is processing the data. Here's what I generally have:
main()
{
//Some statements
g_signal_connect(G_OBJECT(btnGenerate), "clicked", G_CALLBACK(Generate), &mainform);
}
void Generate(GtkWidget *btnGenerate, form_widgets *p_main_form)
{
gtk_spinner_start(GTK_SPINNER(p_main_form->spnProcessing));
Begin_Lengthy_Processing(Parameters, Galore, ...);
//gtk_spinner_stop(GTK_SPINNER(p_main_form->spnProcessing));
}
I have the stop function commented out so I can see the spinner spin even after the function has finished, but the spinner starts after the function is finished, and I suspect it turns on in the main loop.
I also found out that the entire interface freezes during the execution of the long going function.
Is there a way to get it to start and display inside the callback function? I found the same question, but it uses Python and threads. This is C, not Python, so I would assume things are different.
You need to run your lengthy computation in a separate thread, or break it up into chunks and run each of them separately as idle callbacks in the main thread.
If your lengthy computation takes a single set of inputs and doesn’t need any more inputs until it’s finished, then you should construct it as a GTask and use g_task_run_in_thread() to start the task. Its result will be delivered back to the main thread via the GTask’s GAsyncReadyCallback. There’s an example here.
If it takes more input as it progresses, you probably want to use a GAsyncQueue to feed it more inputs, and a GThreadPool to provide the threads (amortising the cost of creating threads over multiple calls to the lengthy function, and protecting against denial of service).
The GNOME developer docs give an overview of how to do threading.
This is what I got:
int main()
{
// Statements...
g_signal_connect(G_OBJECT(btnGenerate), "clicked", G_CALLBACK(Process), &mainform);
// More statements...
}
void Process(GtkWidget *btnGenerate, form_widgets *p_main_form)
{
GError *processing_error;
GThread *start_processing;
gtk_spinner_start(GTK_SPINNER(p_main_form->spnProcessing));
active = true;
if((start_processing = g_thread_try_new(NULL, (GThreadFunc)Generate, p_main_form, &processing_error)) == NULL)
{
printf("%s\n", processing_error->message);
printf("Error, cannot create thread!?!?\n\n");
exit(processing_error->code);
}
}
void Generate(form_widgets *p_main_form)
{
// Long process
active = false;
}
My program, once cleaned up and finished, as there are many other bugs in the program, will be put on GitHub.
Thank you all for your help. This answer comes from looking at all of your answers and comments as well as reading some more documentation, but mostly your comments and answers.
I did something similar in my gtk3 program. It's not that difficult. Here's how I would go about it.
/**
g_idle_add_full() expects a pointer to a function with the signature below:
(*GSourceFunc) (gpointer user_data).
So your function signature must adhere to that in order to be called.
But you might want to pass variables to the function.
If you don't want to have the variables in the global scope
then you can do this:
typedef struct myDataType {
char* name;
int age;
} myDataType;
myDataType person = {"Max", 25};
then when calling g_idle_add_full() you do it this way:
g_idle_add_full(G_PRIORITY_HIGH_IDLE, myFunction, person, NULL);
*/
int main()
{
// Assumming there exist a pointer called data
g_idle_add_full(G_PRIORITY_HIGH_IDLE, lengthyProcessCallBack, data, NULL);
// GTK & GDK event loop continues and window should be responsive while function runs in background
}
gboolean lengthyProcessCallBack(gpointer data)
{
myDataType person = (myDataType) *data;
// Doing lenghthy stuff
while(;;) {
sleep(3600); // hypothetical long process :D
}
return FALSE; // removed from event sources and won't be called again.
}
I have this loop, how would I end the loop?
void loop() {
// read the pushbutton input pin:
a ++;
Serial.println(a);
analogWrite(speakerOut, NULL);
if(a > 50 && a < 300){
analogWrite(speakerOut, 200);
}
if(a <= 49){
analogWrite(speakerOut, NULL);
}
if(a >= 300 && a <= 2499){
analogWrite(speakerOut, NULL);
}
This isn't published on Arduino.cc but you can in fact exit from the loop routine with a simple exit(0);
This will compile on pretty much any board you have in your board list. I'm using IDE 1.0.6. I've tested it with Uno, Mega, Micro Pro and even the Adafruit Trinket
void loop() {
// All of your code here
/* Note you should clean up any of your I/O here as on exit,
all 'ON'outputs remain HIGH */
// Exit the loop
exit(0); //The 0 is required to prevent compile error.
}
I use this in projects where I wire in a button to the reset pin. Basically your loop runs until exit(0); and then just persists in the last state. I've made some robots for my kids, and each time the press a button (reset) the code starts from the start of the loop() function.
Arduino specifically provides absolutely no way to exit their loop function, as exhibited by the code that actually runs it:
setup();
for (;;) {
loop();
if (serialEventRun) serialEventRun();
}
Besides, on a microcontroller there isn't anything to exit to in the first place.
The closest you can do is to just halt the processor. That will stop processing until it's reset.
Matti Virkkunen said it right, there's no "decent" way of stopping the loop. Nonetheless, by looking at your code and making several assumptions, I imagine you're trying to output a signal with a given frequency, but you want to be able to stop it.
If that's the case, there are several solutions:
If you want to generate the signal with the input of a button you could do the following
int speakerOut = A0;
int buttonPin = 13;
void setup() {
pinMode(speakerOut, OUTPUT);
pinMode(buttonPin, INPUT_PULLUP);
}
int a = 0;
void loop() {
if(digitalRead(buttonPin) == LOW) {
a ++;
Serial.println(a);
analogWrite(speakerOut, NULL);
if(a > 50 && a < 300) {
analogWrite(speakerOut, 200);
}
if(a <= 49) {
analogWrite(speakerOut, NULL);
}
if(a >= 300 && a <= 2499) {
analogWrite(speakerOut, NULL);
}
}
}
In this case we're using a button pin as an INPUT_PULLUP. You can read the Arduino reference for more information about this topic, but in a nutshell this configuration sets an internal pullup resistor, this way you can just have your button connected to ground, with no need of external resistors.
Note: This will invert the levels of the button, LOW will be pressed and HIGH will be released.
The other option would be using one of the built-ins hardware timers to get a function called periodically with interruptions. I won't go in depth be here's a great description of what it is and how to use it.
The three options that come to mind:
1st) End void loop() with while(1)... or equally as good... while(true)
void loop(){
//the code you want to run once here,
//e.g., If (blah == blah)...etc.
while(1) //last line of main loop
}
This option runs your code once and then kicks the Ard into
an endless "invisible" loop. Perhaps not the nicest way to
go, but as far as outside appearances, it gets the job done.
The Ard will continue to draw current while it spins itself in
an endless circle... perhaps one could set up a sort of timer
function that puts the Ard to sleep after so many seconds,
minutes, etc., of looping... just a thought... there are certainly
various sleep libraries out there... see
e.g., Monk, Programming Arduino: Next Steps, pgs., 85-100
for further discussion of such.
2nd) Create a "stop main loop" function with a conditional control
structure that makes its initial test fail on a second pass.
This often requires declaring a global variable and having the
"stop main loop" function toggle the value of the variable
upon termination. E.g.,
boolean stop_it = false; //global variable
void setup(){
Serial.begin(9600);
//blah...
}
boolean stop_main_loop(){ //fancy stop main loop function
if(stop_it == false){ //which it will be the first time through
Serial.println("This should print once.");
//then do some more blah....you can locate all the
// code you want to run once here....eventually end by
//toggling the "stop_it" variable ...
}
stop_it = true; //...like this
return stop_it; //then send this newly updated "stop_it" value
// outside the function
}
void loop{
stop_it = stop_main_loop(); //and finally catch that updated
//value and store it in the global stop_it
//variable, effectively
//halting the loop ...
}
Granted, this might not be especially pretty, but it also works.
It kicks the Ard into another endless "invisible" loop, but this
time it's a case of repeatedly checking the if(stop_it == false) condition in stop_main_loop()
which of course fails to pass every time after the first time through.
3rd) One could once again use a global variable but use a simple if (test == blah){} structure instead of a fancy "stop main loop" function.
boolean start = true; //global variable
void setup(){
Serial.begin(9600);
}
void loop(){
if(start == true){ //which it will be the first time through
Serial.println("This should print once.");
//the code you want to run once here,
//e.g., more If (blah == blah)...etc.
}
start = false; //toggle value of global "start" variable
//Next time around, the if test is sure to fail.
}
There are certainly other ways to "stop" that pesky endless main loop
but these three as well as those already mentioned should get you started.
This will turn off interrupts and put the CPU into (permanent until reset/power toggled) sleep:
cli();
sleep_enable();
sleep_cpu();
See also http://arduino.land/FAQ/content/7/47/en/how-to-stop-an-arduino-sketch.html, for more details.
just use this line to exit function:
return;
I'm attempting to write a function that will pull text from different sources (Ethernet client/Serial/etc.) into a single line, then compare them and run other functions based on them. Simple..
And while this works, I am having issues when trying to call a simple Serial.println() from a function OTHER than loop().
So far, I have around 140 lines of code, but here's a trimmed down version of the portion that's causing me problems:
boolean fileTerm;
setup() {
fileTerm = false;
}
loop() {
char character;
String content="";
while (Serial.available()) {
character = Serial.read();
content.concat(character);
delay(1);
}
if (content != "") {
Serial.println("> " + content);
/** Error from Serial command string.
* 0 = No error
* 1 = Invalid command
*/
int err = testInput(content);
}
int testInput(String content) {
if (content == "term") {
fileTerm = true;
Serial.println("Starting Terminal Mode");
return 0;
}
if (content == "exit" && fileTerm == true) {
fileTerm = false;
Serial.println("Exiting Terminal Mode");
return 0;
}
return 1;
}
(full source at http://pastebin.com/prEuBaRJ)
So the point is to catch the "term" command and enter some sort of filesystem terminal mode (eventually to access and manipulate files on the SD card). The "exit" command will leave the terminal mode.
However, whenever I actually compile and type these commands with others into the Serial monitor, I see:
> hello
> term
> test for index.html
> exit
> test
> foo
> etc...
I figure the function is catching those reserved terms and actually processing them properly, but for whatever reason, is not sending the desired responses over the Serial bus.
Just for the sake of proper syntax, I am also declaring the testInput() function in a separate header, though I would doubt this has any bearing on whether or not this particular error would occur.
Any explainable reason for this?
Thanks.
Model: Arduino Uno R3, IDE version: 1.0.4, though this behavior also happened on v1.0.5 in some instances..
It is kinda guessable how you ended up putting delay(1) in your code, that was a workaround for a bug in your code. But you didn't solve it properly. What you probably saw was that your code was too eager to process the command, before you were done typing it. So you slowed it down.
But that wasn't the right fix, what you really want to do is wait for the entire command to be typed. Until you press the Enter key on your keyboard.
Which is the bug in your code right now, the content variable doesn't just contain "term", it also contains the character that was generated by your terminal's Enter key. Which is why you don't get a match.
So fix your code, add a test to check that you got the Enter key character. And then process the command.