Is it possible to read NFC card reader in VC++/MFC. Is it possible to develop a callback function that will read the NFC device, and see once the card is inserted, it takes that value from the card and store it in a DB?
View 3 RepliesI'm using a uC to read the device ID from a One Wire device. I'm trying to have the ID read every second and output to over a USART serial stream for debugging, however I'm having a number of problems getting this to work correctly and I think it has to do with my misunderstanding of memory allocation in this case.
The problem is that when I upload the binary to the uC, it gets the device ID correctly the first time, and from thereafter the program is unstable and starts returning garbage (1st screenshot).
Ideally everything inside of the while loop would be inside of its own function, however I have had nothing but trouble doing that. In fact, when I put that all into it's own function that returns void and takes BUSES as an input, the correct data comes out the first and therefore it somehow exits the "while" loop and never gets back in (2nd screenshot). Another thing I noticed is that when I put the variable declaration outside of the while loop in the code below, I get the same behavior.
I haven't include the code for OWI_DetectPresence and OWI_SendByte ... I've hooked up an oscilloscope and have visually confirmed they are working correctly. Once the OWI_ROM_READ byte is sent over the bus the slave responds with it's device ID. I feel like my issue here is memory allocation and not hardware.
how to fix the issue with the output to USART and how to make this into a function that returns the string of the hex ID?
Code:
int main(void) {
unsigned char OWI_on_bus = FALSE;
// initialize UART for debugging
Init_USART();
[Code].....
Why do we say function as Callback?what does a call back mean?
View 2 Replies View RelatedIn my Project, I'm using my Parent Dialog(TestDlg) as a background dialog.
Child Dialog 1 = Main.cpp & Child Dialog 2 = Dummy.cpp
1. I like to call both dialog continuously one by one.
Using Timer function i called continuously the dialogs.
After 5 minutes getting an error, "0xC000041D An unhanded Exception was encountered during a User Callback".
2. Then, I'm using CGdiPlusBitmap.cpp file to load PNG image into buttons.
After 5 minutes getting an error - "CResource Exception".
For reference test code attached.
I want to do a basic thing but for some strange reason there is something not working.
I need to write to a file but I'm handling all the code in a callback function, which in turn is declared in a class. Here is the architecture of my code:
Code:
int main (int argc, char **argv) {
ImageConverter Aclass;
while(1); //infinite loop
return 0;
[Code] ....
But this doesn't work, the file gets created but it allways overwrites itself which is not what I need to do.
What I am doing wrong? Is it because i am constantly declaring outfile?
There is already a thread with exactly the same problem I have, but the answer to solve the problem isn't stated at the end. Problem with callback as classmember.
View 4 Replies View RelatedI have a function (name Callback), with take some parameter( name Arg). I want to create it before, pass it to other class ( class B). And in class B, call the Callback function with Arg paramater. It's something like this:
class A {
void A::doSomething(int a, bool b){//dosomething};
void A::setCallback(B b) {//I don't know how to do this};
[Code].....
How can i do this? And what happen with I want B can get more type of callback function, which mean I don't know the type of Callback's paramater?
I have a problem with an extension DLL that has an exported function. The function is being exported ok, it is called by a Windows service. The Windows service is using the exported function, and everything works. I am trying to create a file with:
ofstream file;
file.open("C:dir ofile", ios:ut);
file << "text";
But nothing happnes however. There are no errors, the file is just not created. Also, if i try to call MessageBox() in the exported function, nothing happens as well . I have a .h file which exports the function with __declspec(dllexport) DWORD WINAPI functionName(), and also a .cpp file with the function definition. There is no main().
I need to render content of CRichEditCtrl on device context of some CWnd. This code works ok:
Code:
CDC *dc = wnd->GetDC();
CRect cr;
wnd->GetClientRect( &cr );
dc->Rectangle(cr);
cr.right *= 15;
cr.bottom *= 15;
[Code] ...
The problem is that I want to scale the output. I was trying to send message to my control before blitting:
SendMessage( EM_SETZOOM, numer, denom ).
It scaled the control itself, but the blitted context was still the same size as original content CRichEditCtrl (befeoe scaling). Is there any way to blit/render scaled content of CRichEditCtrl to any device context (screen/paper) ?
Why the void pointer passed to testb doesn't continue pointing to the allocated integer after the function call returns.
Code:
#include <stdio.h>
#include <iostream>
void* testa() {
return new int(1);
[Code] ....
I have made a calendar that looks similar to Outlook, and I have the next/previous buttons, but they don't do anything when you click them. how to create the callback so that when I click next it goes to the next month?
View 4 Replies View RelatedI am trying to emulate callback mechanism in C. The code I have is follows:
Code:
#include <stdio.h>
#include <pthread.h>
struct fopen_struct {
char *filename;
char *mode;
void *(*callback) (FILE *);
[Code] .....
If I do a pthread_join in fopen_t() it works perfectly fine. But if I do that in main() I get a segmentation fault error. I want to call it in main() because I want it to be non-blocking, is there any solution?
I have an application based around a WCF Duplex service. I have problems when the user "Restarts" the work the application does... under the hood, the client side closes the connection to the WCF service and creates another. The Service contract is defined like so...
[ServiceContract(Namespace="net.tcp://namespace.MyService",
SessionMode=SessionMode.Required,
CallbackContract=typeof(IServiceCallback))]
public interface IMyService {
[OperationContract(IsOneWay=true)]
[Code] ....
The issue I see is that the _context.Close() call always times out and throws an exception. Although I'm then aborting the channel, this feels wrong to me, and I believe it's the cause of freezing in my application. Why the Close() call fails?
I missed something earlier regarding my callback implementation that might be relevant. It looks something like this:
[Callbackbehavior(ConcurrencyMode = ConcurrencyMode.Single,
UseSynchronizationContext = false,
IncludeExceptionDetailInFaults = true)]
public class CallbackImplementation : IServiceCallback {
public void SendMessage(string message){
// Do something with the message
} }
The exception message is "The ServiceHost close operation timed out after 00:00:30. This could be because a client failed to close a sessionful channel within the required time. The time allotted to this operation may have been a portion of a longer timeout.". There's no inner exception.
The big problem is that the client application freezes when the main application process is started after one client has been disposed and a new one created. I've also noticed that when you close the WPF application, it doesn't close properly and keeps running in the background, preveting you from starting a new instance.
I'm developing a short c++ program to scan all devices connected to the system through the USB connections.
I have used libusb to scan them and it really works but this library does not provide me with the mounting point, so I get a list of devices including manufacturer, serial number, etc but not the mounting point.
I have also used libudev library but it seems to happen something similar...
I need to get the mounting point for all USB devices connected to the board, you know: /dev/ttyUSB0 ....
I am supposed to write a C program to send through USB interface to the analog device AD9914. Now I am doing the USB interface part where my computer has to detect the AD when it is plugged in and send the signals to it. I have to write the program to detect the device when it is plugged in. What kind of functions can I use? I know that the registry stores the device when it is plugged in. What functions are available to read?
View 2 Replies View RelatedI am looking to retrieve data from a USB device, this device is a fingerprint scanner. Because I bought it online and wasn't reading carefully enough, drivers and other installation programs weren't included. Send it back? Nah . . .
I want to see if it is possible to retrieve data from this device. To be honest, I don't even know if it's possible, but I would love to give it a whack.
I looked into making INF files and things Microsoft has put out, but I honestly don't know where to start simply because I have absolutely no experience doing this. I have a program set up to organize the data and such, I just need to find a way to actually get it.
What should I research and look into? Are drivers necessary?
Here is a little more information :-)
I want to save data from a fingerprint scanner.I bought a fingerprint scanner, but nothing came with it (drivers, software, etc.). I decided to not return it and see what fun I could have.
I have no code written up yet (mainly because I don't know where to start). But I looked into the device a little...Microsoft recognizes it as a "Fingerprint Scanner" but is still considered unrecognized.I have the USB identifier (at work right now, don't have it on hand)...
Is it even possible to communicate with the device without the initial drivers.Do I really need drivers for the device, or can I communicate with it as it is now.If I do need drivers, where should I start?What should I look into to get communicating with the device?
I need to get the network device name for the given ip address..
I tried with dns.getHostByaddress but it didn't worked..
What I want to do is abstract and model a device (more specifically in this case, an IMU) in an embedded system.
Now, there are a couple of gotchas:
- It is basically a framework, which means that it should work with any device, any platform and any bus.
- It is an embedded system, so power consumption and memory consumption must be reduced. It is not a PC.
- It cannot be too complex, because I fear that will just make people scrap it and rewrite it from scratch :P
- It should aim for as little code as possible to write the whole model, of course. Adding 100 lines of code for each register would be a bummer.
That said, I must also model the current system, which means that the current platform, the current bus (which is I2C) and the specific IMU model (I have a datasheet).
So the model I am thinking of currently is this:
First, I have a platform. It will know what bus a device is connected on and contains the buses (or specifically, the instances of the buses). It consists of a specific class for each platform and a base. Here are the two I have now:
Code:
namespace Sensors
{
template<typename Platform_t> class GPS;
}
namespace Platforms
{
class RaspberryPi: public PlatformBase
[Code]....
Currently I am making the assumption that all platforms will have an I2c bus and UART bus, but I'm not sure about that. We have only one platform ATM, though, so for now this holds. I'm guessing I might have to move it to the specific platforms later and get rid of PlatformBase.GetI2CBus is a problematic one related to registers, but I'll get back to that.
UART is simple to model since it's just a block read and write, so:
Code:
namespace Buses
{
class UART
{
public:
UART(const std::string& UARTPath): m_Open(false), m_PathToUART(UARTPath) {}
[Code]....
I'm probably going to handle all errors through exceptions. So if I can't open the UART bus, I'll throw an exception.
The I2C bus is a problem. I have a model which deals with it on a register-based level, but ideally I'd like to be able to model and use the devices on the I2C bus on a flag-based level (ie, I have names for each individual flag in the registers which I can read or write to directly instead of writing a hexadecimal value directly to each register).
Here is code:
Code:
namespace Buses {
template<unsigned int Id>
class I2CDevice {
public:
I2CDevice(I2C& Bus): m_Bus(Bus) {}
template<typename T>
[Code]....
So I2CDevice does some checks to see that the data to write to a register is either 8 or 16 bits. It does not check that the size to write matches the register's size, but another class does not.
The idea is also that it checks which device is currently active on the bus, and if it's not the current I2CDevice, then it simply selects that before attempting to read or write (the Open call).
This is not meant for multi-threaded environments. Yet, anyway.
The Impl2::Read/Write just dispatches the call so it calls the correct function for writing and reading the correct size, depending on the size of the data.
This is all well and good, but I2C works with registers, so of course I want a class to model a register which I can read and write to directly. It must tie into the bus class since the bus class is the one that abstracts reads and writes on the bus.
The register class looks like:
Code:
template<unsigned int Bits, unsigned int RegisterId, typename Bus_t>
class Register {
public:
typedef typename Impl::RegisterBase<Bits>::Storage_t Storage_t;
static_assert(!std::is_same<Bus_t, Buses::UART>::value, "Cannot read and write registers on the UART bus.");
static_assert(Bits == 8 || Bits == 16 || Bits == 32 || Bits == 64, "Number of bits must be 8, 16, 32 or 64.");
auto Write(Storage_t Data) -> void
[Code]....
I think this explains itself, except for the Regs struct, which is an experiment by me to enable myself to access registers via Regs.Config, etc.
What is missing is the ability to access and read/write the individual bits inside the registers. I am thinking a two-way access, where you can write to individual bits, but must call .Write() to commit the write to the register for efficiency.
I haven't actually written this. I don't know a good way ATM. I don't want to add a lot of variables and a write function because that would use 1 byte for every bit which is unacceptable.
I don't want to add a lot of code to make it work, either. A good get/set class would be nice, but I can't see that working. The register must store all state and any subsequent classes must not store any state or overhead will increase.
Finally, yes, I know a lot is incomplete and untested. It probably won't even compile. But that is for later. First is finishing the model.
It would be nice if things such as the platform and buses could be made static because there will only be one instance at any time, and that would save overhead if I don't have to store objects or references to them, but I haven't figured out how to achieve this.
I got a assignment in which i have to write codes for execution of certain commands.
One of the command is set_time. if user enters set_time 12:12:12
The time should get reset to 12:12:12 no matter what it is now.
I have a college project which is a car racing game using C++ and the old-school graphics library BGI. After I draw the map and placed the objects(Car,obstacles,road's borders etc..)I added Sleep(); function to the function named Obstacles(); but the problem is, I can't move the car with the right&left arrows.a
Another problem,If I added a cleardevice(); command all objects disappears only the obstacles function keeps working. the Code is here:
char c;
do{
c = (char)getch();
if (c == KEY_LEFT) {
x = x - 10, x1 = x1 - 10;
} if (c == KEY_RIGHT) {
x = x + 10, x1 = x1 + 10;
[code].....
note: this is not the whole code, it's only a small portion of it, not a debugging question only need a hint how to fix it.
I am trying to fetch data from the USB device(say pendrive) connected to the USB port of a system. I have attached code.c file which I have wriiten for the same purpose, please find it. Here I am able to open the device file and read some random raw data which is in the log.txt file (also attached to this mail). But I want it to fetch data like minicom/teraterm does.
What methods and libraries I can use to do it successfully and how can it be done.
Write code to do the following:
1) declare a variable ptr as a pointer to int and initialize it to NULL
2) dynamically allocate memory for an array of 100 elements
3) read 100 elements from the standard input device and store them in the array.
This is what I have so far, I'd like to know if its ok or if something is wrong.
int *ptr = NULL;
ptr = new int[100];
cin >> dataPtr [arr];
My question is that I have C++ function which has a IDispatch input as argument.
I am trying to read the struct from IDispatch.
So basically, the struct definition is
struct MyStruct {
void *m_pValue;
};
I can get the ITypeInfo and read the whole structure definition from it. But I do not know how to read the struct instance value. I am dumping all the info from ITypeInfo
TYPEATTR
========
guid {A1CB710C-8D50-3181-BB38-65CE2E98F9A6} _GUID
lcid 0x00000000 unsigned long
dwReserved 0x00000000 unsigned long
memidConstructor 0xffffffff long
memidDestructor 0xffffffff long
[Code] ....
I have a jpg file. I have extracted the width and the length of the image. I have done that with some codes and markers. Now I need the image data starts as from that place i would like read the data and print the pixel value. I would like to display the pixels later.
View 2 Replies View RelatedSo I'm trying to do a homework assignment, where I read a uml about a bank program, and just create it. Here is the UML. So while working on Bank, the top one, i've come up with this so far.
Code:
#include <iostream>
#include <string>
using namespace std;
class bank
{ string name;
int routingNum;
[Code] ....
I'm assuming that's what the uml wants. However I can't seem to access that private class. Idk why. I declared it as an object in the main.
I am trying to read and store a txt file with format below:
2.5;abc;2,4000
2.5;bef;3,2000
2.5;ref;3,1000
I try the fscanf( pFile, "%d;%s;%d,%d", buffer,buffer2,buffer3,buffer4 ); to store 2.5 to buffer, abc to buffer2, 2 to buffer 3 and 4000 to buffer 4 on first line.
However, it doesn't work. How can I achieve this? I want to read the 2nd line and so on.
Code:
char buffer[100]="";
char buffer2[100]="";
char buffer3[100]="";
char buffer4[100]="";
FILE * pFile=NULL;
pFile = fopen("C: est est.txt", "r");
[Code] ....