I am receiving the following error:
error: expected constructor, destructor, or type conversion before ‘(’ token
Here is the source code that I have written:
void setup() {
pinMode(1,OUTPUT);
[...]
pinMode(13,INPUT);
}
int i = 1;
bool pushed = digitalRead(13);
bool val = 0;
randomSeed(analogRead(0));
void loop() {
if (pushed == 1) {
for (i = 1; i < 9; i++) {
val = random(2);
digitalWrite(i,val);
}
}
}
The variables and the setup are OK; the error is located on the for line. Can anyone tell me how to fix this?
(edit : added the begining of the script, and sorry for the presentation (first question here)
(edit : looks like the error is not in the "i" definition. I'm using an Arduino UNO SMD Edition, if that helps (and the arduino alpha 0022 linux version of the IDE) )
EDIT: okay guys, solved now. It appears that my version of Arduino IDE was not completely downloaded, and that I put the randomSeed in the wrong place (it should be in the setup function.) (when i did put it in the setup function before updating, it shown an error message, saying /opt/arduino/lib/math.h was missing something (or something like that, i don't have the full message) ). Thanks for your help and i hope i'll be able to help you in arduino soon!
for (int i = 1; i < 9; i++)
is valid in C99/C11 but not valid in C89.
If you use a C89 compiler you have to define i outside the for loop clauses:
int i;
for (i = 1; i < 9; i++)
Also in C89, all declarations have to follow the left brace of a block, you cannot freely mix declarations and statements.
You appear to have a statement randomSeed(analogRead(0)); floating in between your setup() and loop() function definitions.
Move it and any other IO operations to the end of the setup() function so you read after setting up the pin directions:
int i = 1;
bool pushed;
bool val = 0;
void setup() {
pinMode(1,OUTPUT);
[...]
pinMode(13,INPUT);
pushed = digitalRead(13);
randomSeed(analogRead(0));
}
void loop() {
if (pushed == 1) {
for (i = 1; i < 9; i++) {
val = random(2);
digitalWrite(i,val);
}
}
}
That will reading the value of pin 13 into pushed only once ( e.g. you are holding a button when powering it on ); depending what you want it to do you may want to move the read to the start of loop() so writes random values whenever the button is pressed.
In C (previous to C99), it's not permissible to define a new variable in the first expression of a for loop. Try declaring your variable i at the top of the function instead.
#define pinMode1 1
#define pinMode2 13
bool pushed;
bool val = 0;
void setup() {
// Declare OUTPUT pin.
pinMode(pinMode1, OUTPUT);
// Declare INPUT pin.
pinMode(pinMode2, INPUT);
// Set digitalRead().
pushed = digitalRead(pinMode2);
// Initializes the pseudo-random number generator.
randomSeed(analogRead(0));
}
void loop() {
if (pushed == 1) {
for (int i = 1; i < 9; i++) {
val = random(2);
// Set i to HIGH or LOW.
digitalWrite(i, val);
}
}
}
Related
I'm trying to build a tachometer in C++ for my ESP32. When I uncomment Serial.printf("outside rev: %d \n", rev); outside of the conditional it works, but when I comment it I get values that are orders of magnitude greater than they should be (700 revolutions without, vs 7 revolutions with). My best guess is that the print statement is slowing the loop() down just enough for incrementRevolutions() to toggle the global variable passedMagnet from true to false before the next loop. That would make sense, since a delay in updating passedMagnet would allow newRevCount++; to be triggered multiple times. But this is obviously something I can't debug with either print statements or step-through debugging given the time-sensitive nature of the race condition.
bool passedMagnet = true;
int incrementRevolutions(int runningRevCount, bool passingMagnet)
{
// Serial.printf("passedMagnet: %d , passingMagnet %d , runningRevCount: %d \n", passedMagnet, passingMagnet, runningRevCount);
int newRevCount = runningRevCount;
if (passedMagnet && passingMagnet)
{ //Started a new pass of the magnet
passedMagnet = false;
newRevCount++;
}
else if (!passedMagnet && !passingMagnet)
{ //The new pass of the magnet is complete
passedMagnet = true;
}
return newRevCount;
}
unsigned long elapsedTime = 0;
unsigned long intervalTime = 0;
int rev = 0;
void loop()
{
intervalTime = millis() - elapsedTime;
rev = incrementRevolutions(rev, digitalRead(digitalPin));
// Serial.printf("outside rev: %d \n", rev);
if (intervalTime > 1000)
{
Serial.printf("rev: %d \n", rev);
rev = 0;
elapsedTime = millis();
}
}
Is this a known gotcha with Arduino or C++ programming? What should I do to fix it?
I think the test is to blame. I had to rename and move things a bit to visualize the logic, sorry about that.
bool magStateOld = false; // initialize to digitalRead(digitalPin) in setup()
int incrementRevolutions(int runningRevCount, bool magState)
{
int newRevCount = runningRevCount;
// detect positive edge.
if (magState && !magStateOld) // <- was eq. to if (magState && magStateOld)
// the large counts came from here.
{
newRevCount++;
}
magStateOld = magState; // record last state unconditionally
return newRevCount;
}
You could also write it as...
int incrementRevolutions(int n, bool magState)
{
n += (magState && !magStateOld);
magStateOld = magState;
return n;
}
But the most economical (and fastest) way of doing what you want would be:
bool magStateOld;
inline bool positiveEdge(bool state, bool& oldState)
{
bool result = (state && !oldState);
oldState = state;
return result;
}
void setup()
{
// ...
magStateOld = digitalRead(digitalPin);
}
void loop()
{
// ...
rev += (int)positiveEdge(digitalRead(digitalPin), magStateOld);
// ...
}
It's reusable, and saves both stack space and unnecessary assignments.
If you cannot get clean transitions from your sensor (noise on positive and negative edges, you'll need to debounce the signal a bit, using a timer.
Example:
constexpr byte debounce_delay = 50; // ms, you may want to play with
// this value, smaller is better.
// but must be high enough to
// avoid issues on expected
// RPM range.
// 50 ms is on the high side.
byte debounce_timestamp; // byte is large enough for delays
// up to 255ms.
// ...
void loop()
{
// ...
byte now = (byte)millis();
if (now - debounce_timestamp >= debounce_delay)
{
debounce_timestamp = now;
rev += (int)positiveEdge(digitalRead(digitalPin), magStateOld);
}
// ...
}
Context
The context of the problem is that I am currently writing a small library for use with the Arduino in order to act as a game controller. The problem I am encountering has more to do with C++ than anything Arduino specific however.
I've included the libraries' header and source code below, followed by the Arduino code. I've truncated it where possible.
Problem
In short, only the last switch / action I define actually gets properly handles.
These actions get defined in the Arduino setup function. For example:
controller.addSwitchContinuous(10, 0); // Pin 10; btn index 0
means that pin 10 gets mapped to button 0. When pin 10 is switched closed this is treated as the button being pressed. This works fine for a single action but when I start adding more only the last action actually works. So in the following example only pin 9 is recognized:
controller.addSwitchContinuous(10, 0); // <-- Doesn't work
controller.addSwitchContinuous(9, 1); // <-- Works
This goes for any arbitrary number of actions:
controller.addSwitchContinuous(10, 0); // <-- Doesn't work
controller.addSwitchContinuous(9, 1); // <-- Doesn't work
controller.addSwitchContinuous(8, 2); // <-- Doesn't work
controller.addSwitchContinuous(7, 3); // <-- Works
Potential causes
I am fairly novice with C++ so this I suspect I'm doing something wrong with pointers. More specifically, something seems wrong with how the Joystick_ instance gets passed around.
I have been fiddling with the constructor and trying to use references instead of pointers but I couldn't get it to work properly.
I can confirm the iteration in JFSF::loop does iterate over all actions, if I modify it with:
void JFSF::loop()
{
for (int n = 0; n < _nextActionIndex; n++)
{
if (_actions[n])
{
_actions[n]->loop();
_joystick->setButton(n, PRESSED); // Debug: Set button pressed, regardless of switch.
}
}
if (_doSendState)
{
_joystick->sendState();
}
}
then buttons 0 through n get pressed as expected. It is possible that loop() isn't properly being called, but I would expect it to fail for the N = 1 case as well in that case. Furthermore the fact the last action always succeeds would suggest the iteration is ok.
Full code
// JFSF.h
#ifndef JFSF_h
#define JFSF_h
// ... include for Arduino.h and Joystick.h; bunch of defines
namespace JFSF_PRIV
{
class AbstractAction
{
public:
virtual void loop();
};
/* A Switch that essentially acts as a push button. */
class SwitchContinuousAction : public AbstractAction
{
public:
SwitchContinuousAction(Joystick_ *joystick, int pin, int btnIndex);
void loop();
private:
Joystick_ *_joystick;
int _pin;
int _btnIndex;
};
} // namespace JFSF_PRIV
class JFSF
{
public:
JFSF(Joystick_ *joystick, bool doSendState); // doSendState should be true if Joystick_ does not auto send state.
void loop();
void addSwitchContinuous(int inputPin, int btnIndex);
private:
Joystick_ *_joystick;
JFSF_PRIV::AbstractAction *_actions[MAX_ACTIONS];
int _nextActionIndex;
bool _doSendState;
};
#endif
Source file (trimmed):
// JFSF.cpp
#include "Arduino.h"
#include "Joystick.h"
#include "JFSF.h"
#define PRESSED 1
#define RELEASED 0
// Private classes
namespace JFSF_PRIV
{
SwitchContinuousAction::SwitchContinuousAction(Joystick_ *joystick, int pin, int btnIndex)
{
_joystick = joystick;
_pin = pin;
_btnIndex = btnIndex;
pinMode(_pin, INPUT_PULLUP);
}
void SwitchContinuousAction::loop()
{
int _state = digitalRead(_pin) == LOW ? PRESSED : RELEASED;
_joystick->setButton(_btnIndex, _state);
}
} // namespace JFSF_PRIV
JFSF::JFSF(Joystick_ *joystick, bool doSendState)
{
_joystick = joystick;
_nextActionIndex = 0;
_doSendState = doSendState;
}
void JFSF::addSwitchContinuous(int inputPin, int btnIndex)
{
JFSF_PRIV::SwitchContinuousAction newBtnAction(_joystick, inputPin, btnIndex);
_actions[_nextActionIndex++] = &newBtnAction;
}
void JFSF::loop()
{
for (int n = 0; n < _nextActionIndex; n++)
{
if (_actions[n])
{
_actions[n]->loop();
}
}
if (_doSendState)
{
_joystick->sendState();
}
}
For completeness sake, this is the code for the Arduino, but it is pretty much just declarations:
#include <JFSF.h>
// ... A bunch of const declarations used below. These are pretty self explanatory.
// See: https://github.com/MHeironimus/ArduinoJoystickLibrary#joystick-library-api
Joystick_ joystick(HID_REPORT_ID,
JOYSTICK_TYPE_JOYSTICK, // _JOYSTICK, _GAMEPAD or _MULTI_AXIS
BTN_COUNT, HAT_SWITCH_COUNT,
INCLUDE_X_AXIS, INCLUDE_Y_AXIS, INCLUDE_Z_AXIS,
INCLUDE_RX_AXIS, INCLUDE_RY_AXIS, INCLUDE_RZ_AXIS,
INCLUDE_RUDDER, INCLUDE_THROTTLE,
INCLUDE_ACCELERATOR, INCLUDE_BRAKE, INCLUDE_STEERING);
JFSF controller(&joystick, !DO_AUTO_SEND_STATE);
void setup() {
joystick.begin(DO_AUTO_SEND_STATE);
controller.addSwitchContinuous(10, 0); // <-- Doesn't work
controller.addSwitchContinuous(9, 1); // <-- Works
}
void loop() {
controller.loop();
}
References
ArduinoJoystickLibrary (Source for Joystick_) can be found here: https://github.com/MHeironimus/ArduinoJoystickLibrary#joystick-library-api
I dont really understand your code. Please read How to create a Minimal, Complete and Verifiable example. Anyhow, the following is certainly wrong and likely the cause of your problem:
void JFSF::addSwitchContinuous(int inputPin, int btnIndex)
{
JFSF_PRIV::SwitchContinuousAction newBtnAction(_joystick, inputPin, btnIndex);
_actions[_nextActionIndex++] = &newBtnAction;
}
Lets rewrite it a bit for clarity:
void foo(){
T bar;
container[index] = &bar;
}
What happens here is that bar gets destroyed when it goes out of scope, hence the pointer you put into the container, points to garbage. Presumably somewhere else in your code you are dereferencing those pointers, which is undefined behaviour (aka anything can happen).
Long story short: It is a common pattern among c++ beginners to overuse pointers. Most likely you should make container a container of objects rather than pointers and make use of automatic memory managment instead of trying to fight it.
Thanks to #user463035818 and #drescherjm for identifiying the actual problem.
So in the end I fixed it by simply moving the Action object creation up to the Arduino code (where it's essentially global) and passing references to those objects to the controller.
In code this translates to:
JFSF.cpp
void JFSF::addAction(JFSF_PRIV::AbstractAction *action){
_actions[_nextActionIndex++] = action;
}
Arduino code (ino)
// See code in original post
JFSF controller(&joystick, !DO_AUTO_SEND_STATE);
JFSF_PRIV::SwitchContinuousAction btnOne(&joystick, 10, 0);
JFSF_PRIV::SwitchContinuousAction btnTwo(&joystick, 9, 1);
void setup() {
joystick.begin(DO_AUTO_SEND_STATE);
// controller.addSwitchContinuous(10, 0); // Pin 10; btn index 0
// controller.addSwitchContinuous(9, 1); // Pin 9 ; btn index 1
controller.addAction(&btnOne);
controller.addAction(&btnTwo);
}
// loop() is unchanged
its my first time here. My code is suppose to make two ultrasonic sensors function at the same time using an mbed. However, i cant seem to make both classes void us_right() and void us_left() in the code run concurrently. Help please :(
#include "mbed.h"
DigitalOut triggerRight(p9);
DigitalIn echoRight(p10);
DigitalOut triggerLeft(p13);
DigitalIn echoLeft(p14);
//DigitalOut myled(LED1); //monitor trigger
//DigitalOut myled2(LED2); //monitor echo
PwmOut steering(p21);
PwmOut velocity(p22);
int distanceRight = 0, distanceLeft = 0;
int correctionRight = 0, correctionLeft = 0;
Timer sonarRight, sonarLeft;
float vo=0;
// Velocity expects -1 (reverse) to +1 (forward)
void Velocity(float v) {
v=v+1;
if (v>=0 && v<=2) {
if (vo>=1 && v<1) { //
velocity.pulsewidth(0.0014); // this is required to
wait(0.1); //
velocity.pulsewidth(0.0015); // move into reverse
wait(0.1); //
} //
velocity.pulsewidth(v/2000+0.001);
vo=v;
}
}
// Steering expects -1 (left) to +1 (right)
void Steering(float s) {
s=s+1;
if (s>=0 && s<=2) {
steering.pulsewidth(s/2000+0.001);
}
}
void us_right() {
sonarRight.reset();
sonarRight.start();
while (echoRight==2) {};
sonarRight.stop();
correctionRight = sonarLeft.read_us();
triggerRight = 1;
sonarRight.reset();
wait_us(10.0);
triggerRight = 0;
while (echoRight==0) {};
// myled2=echoRight;
sonarRight.start();
while (echoRight==1) {};
sonarRight.stop();
distanceRight = ((sonarRight.read_us()-correctionRight)/58.0);
printf("Distance from Right is: %d cm \n\r",distanceRight);
}
void us_left() {
sonarLeft.reset();
sonarLeft.start();
while (echoLeft==2) {};
sonarLeft.stop();
correctionLeft = sonarLeft.read_us();
triggerLeft = 1;
sonarLeft.reset();
wait_us(10.0);
triggerLeft = 0;
while (echoLeft==0) {};
// myled2=echoLeft;
sonarLeft.start();
while (echoLeft==1) {};
sonarLeft.stop();
distanceLeft = (sonarLeft.read_us()-correctionLeft)/58.0;
printf("Distance from Left is: %d cm \n\r",distanceLeft);
}
int main() {
while(true) {
us_right();
us_left();
}
if (distanceLeft < 10 || distanceRight < 10) {
if (distanceLeft < distanceRight) {
for(int i=0; i>-100; i--) { // Go left
Steering(i/100.0);
wait(0.1);
}
}
if (distanceLeft > distanceRight) {
for(int i=0; i>100; i++) { // Go Right
Steering(i/100.0);
wait(0.1);
}
}
}
wait(0.2);
}
You need to use some mechanism to create new threads or processes. Your implementation is sequential, there is nothing you do that tells the code to run concurrently.
You should take a look at some threads libraries (pthreads for example, or if you have access to c++11, there are thread functionality there) or how to create new processes as well as some kind of message passing interface between these processes.
Create two threads, one for each ultrasonic sensor:
void read_left_sensor() {
while (1) {
// do the reading
wait(0.5f);
}
}
int main() {
Thread left_thread;
left_thread.start(&read_left_sensor);
Thread right_thread;
right_thread.start(&read_right_sensor);
while (1) {
// put your control code for the vehicle here
wait(0.1f);
}
}
You can use global variables to write to when reading the sensor, and read them in your main loop. The memory is shared.
Your first problem is that you have placed code outside of your infinite while(true) loop. This later code will never run. But maybe you know this.
int main() {
while(true) {
us_right();
us_left();
} // <- Loops back to the start of while()
// You Never pass this point!!!
if (distanceLeft < 10 || distanceRight < 10) {
// Do stuff etc.
}
wait(0.2);
}
But, I think you are expecting us_right() and us_left() to happen at exactly the same time. You cannot do that in a sequential environment.
Jan Jongboom is correct in suggesting you could use Threads. This allows the 'OS' to designate time for each piece of code to run. But it is still not truly parallel. Each function (classes are a different thing) will get a chance to run. One will run, and when it is finished (or during a wait) another function will get its chance to run.
As you are using an mbed, I'd suggest that your project is an MBED OS 5 project
(you select this when you start a new project). Otherwise you'll need to use an RTOS library. There is a blinky example using threads that should sum it up well. Here is more info.
Threading can be dangerous for someone without experience. So stick to a simple implementation to start with. Make sure you understand what/why/how you are doing it.
Aside: From a hardware perspective, running ultrasonic sensors in parallel is actually not ideal. They both broadcast the same frequency, and can hear each other. Triggering them at the same time, they interfere with each other.
Imagine two people shouting words in a closed room. If they take turns, it will be obvious what they are saying. If they both shout at the same time, it will be very hard!
So actually, not being able to run in parallel is probably a good thing.
I have a program which allows the user to play Dominoes against 3 CPU players, with varying difficulty. Each CPU player can be either Beginner, Intermediate or Expert, and each difficulty has it's own class. If I initiate my 3 CPU players at the beginning of my 'Window' class (below), the program runs fine.
In Window.h
public:
Window(QWidget *parent = 0);
Intermediate *cpu1;
Beginner *cpu2;
Intermediate *cpu3;
In Window.cpp
Window::Window(QWidget *parent):QDialog(parent) {
cpu1 = new Intermediate;
cpu2 = new Beginner;
cpu3 = new Intermediate;
}
However I want the user to be able to select the CPU difficulties at the beginning of the game, so I now have a function within 'Window' that creates the objects. As soon as I call this function the game freezes and I get an error message pop up saying telling me the program has ended unexpectedly.
void Window:: startGame(){
cpu1 = new Intermediate;
cpu2 = new Beginner;
cpu3 = new Intermediate;
}
If anyone would be able to explain to me what is going on and what I can do to get around this that would be great.
Intermediate.cpp (Beginner.cpp is almost identical)
#include "intermediate.h"
Intermediate::Intermediate()
{
tilePlaced = false;
skipGo = false;
}
void Intermediate::findDoubles(int a[7][2]){
for(int i = 0; i < 7; i++){ // Creates new doubles list after each go.
doublesList[i] = 0;
}
for(int i = 0; i < 7; i++){ // Creates a list of doubles
if ((a[i][0] == a[i][1]) && (a[i][0] != 7)){
doublesList[a[i][0]] = 1;
}
}
}
bool Intermediate::addDomino(){} // Function that finds best domino to replace and returns bool
if(tilePlaced == false){
pass++;
text += "\nPassed turn";
return false;
}
else{
pass = 0;
text += QString("\nPlaced [%1 : %2]").arg(a).arg(b);
return true;
}
}
One way to start would be to narrow down which class is causing the fault. Does it work if they are all Beginner, or if they are all Intermediate? If so then the other one is causing the problem.
Is there a way to update the number of joysticks plugged in at run-time other than constantly calling remove_joystick() then install_joystick? This proves to be extremely slow (goes from 60 FPS to around 5).
Allegro 4.2 answers only please...
void Joystick::Update() {
//If joystick input was lost, attempt to reacquire.
if(GetNumJoysticks() == 0) {
throw InputNotAvailableException("Joystick");
}
//If all joysticks were deleted remove input and do nothing.
if(_numjoysticks == 0) {
remove_joystick();
return;
}
//Update state information
if(poll_joystick() < 0) {
throw InputNotAvailableException("Joystick");
}
for(int i = 0; i < _numButtons; ++i) {
_prevButtons[i].b = _curButtons[i].b;
_prevButtons[i].name = _curButtons[i].name;
_curButtons[i].b = joy[_joyNumber].button[i].b;
_curButtons[i].name = joy[_joyNumber].button[i].name;
}
for(int i = 0; i < _numSticks; ++i) {
for(int j = 0; j < joy[_joyNumber].stick[i].num_axis; ++j) {
_prevSticks[i].axis[j].name = _curSticks[i].axis[j].name;
_prevSticks[i].axis[j].pos = _curSticks[i].axis[j].pos;
_prevSticks[i].axis[j].d1 = _curSticks[i].axis[j].d1;
_prevSticks[i].axis[j].d2 = _curSticks[i].axis[j].d2;
_curSticks[i].axis[j].name = joy[_joyNumber].stick[i].axis[j].name;
_curSticks[i].axis[j].pos = joy[_joyNumber].stick[i].axis[j].pos;
_curSticks[i].axis[j].d1 = joy[_joyNumber].stick[i].axis[j].d1;
_curSticks[i].axis[j].d2 = joy[_joyNumber].stick[i].axis[j].d2;
}
_prevSticks[i].flags = _curSticks[i].flags;
_prevSticks[i].name = _curSticks[i].name;
_curSticks[i].flags = joy[_joyNumber].stick[i].flags;
_curSticks[i].name = joy[_joyNumber].stick[i].name;
}
}
int Joystick::GetNumJoysticks() {
remove_joystick();
if(install_joystick(JOY_TYPE_DIRECTX)) {
return 0;
}
return (num_joysticks);
}
The 4.x series does not. The 5.x series does.
You'll have to either listen for native OS events using custom platform specific code (assuming such things exist) and only call the Allegro deinit/init functions when a change is detected, or require the user to initiate joystick refresh manually.
Under Linux, you could inotify_add_watch() /dev/input to check for changes. Looking at the 4.4 Allegro code, looks like you'd want to call the Win32 functions joyGetNumDevs() and joyGetPos(). Something like:
int WIN_MAX_JOYSTICKS = joyGetNumDevs(); // this should never change
JOYINFO ji;
int pluggedin_count = 0;
for (int i = 0; i < WIN_MAX_JOYSTICKS; ++i)
if (joyGetPos(i, &ji) == JOYERR_NOERROR) ++pluggedin_count;
if (pluggedin_count != last_pluggedin_count) /* reinit Allegro */
You'd have to do that every N seconds.
Those joy* functions are Windows functions, so read MSDN docs to learn how to use them.