C++ :: Look-up Mounting Point Of USB Device
Apr 15, 2013
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 ....
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Jun 26, 2013
I have one code that use MPI broadcast and I want to change it into Asynchronous Point to Point communication. I am newbie in Parallel programming. Looking for implementation of one simple same program in broadcast and P2P ?
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Sep 25, 2014
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?
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Jun 16, 2014
I 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?
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Aug 13, 2013
I need to get the network device name for the given ip address..
I tried with dns.getHostByaddress but it didn't worked..
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Oct 13, 2013
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.
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Sep 10, 2013
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.
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Dec 14, 2014
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.
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Jan 7, 2015
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?
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Sep 26, 2013
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.
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Feb 19, 2014
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];
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Mar 9, 2012
I'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].....
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Mar 4, 2013
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) ?
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Jan 3, 2015
I don't know why this doesn't work. It doesn't return any errors, but it does the polynomial equation wrong. I tried using "^" instead of "pow" and it still does it wrong. I'm getting results like "-897123897" instead of "3". This is the code:
Code:
#include <stdio.h>
#include <conio.h>
#include <math.h>
int main()
[code]....
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May 14, 2013
I am reading about positive and negative infinity in c++ and i am trying to implement them in a fixed point math arthimethic implementation
I can see that max of a int will be equal to std::numeric_limits<int>::max();
and min value of the int will be equal to std::numeric_limits<int>::min();
in c++
Here as i am defining the int max and int min manually in my fixed point math implementation, my doubt is
int min = -int max; or int min = -int max -1; ?
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Mar 16, 2014
Code:
#include<stdio.h>
#include<conio.h>
void main()
{
float i;
i=0.7;
[Code] ....
If i do run the above program in turbo C/C++ complier, it outputs "h". But,if i change the code as i=0.6 and if (i<0.6), it outputs "w". Even if i change it to i=0.8 and if(i<0.8), then also it outputs "w".
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May 8, 2014
Code:
#include<stdio.h>
#include<conio.h>
float square(float);
void main() { clrscr();
float a,b;
printf("ENter a Number");
scanf("%f",&a);
[Code] ....
In the above program, I am calculating the square of float number. But sometimes the number is entered as NAN and sometimes Output is NAN. What is NAN? I am entering floating point number, then y NAN is entered?
SEE the Image attached for the OUTPUT.
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Oct 9, 2013
I have been writing a fixed point library the would handle fixed point numbers with an 8:24 whole/fraction ratio. This has been working quite well but since I have a 24 bit fractional part, it should be able to store 2^(-24).
Code:
long long fraction_part = 0;
long long divisor = 1;
while(*string) {
fraction_part *= 10;
fraction_part += *string - '0';
divisor *= 10;
string++;
}
fraction_part <<= 24;
fraction_part /= divisor;
The issue here is that since the smallest possible fraction is 2^(-24) the divisor could end up needing more than 64 bits and so won't work. I'm not quite sure how else I could do this.
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Oct 15, 2014
I have to create dynamic array, where each element of it points to some value. I know how to create dynamic array
Code: array_record * record_1 = (array_record*)malloc( (group!/(2!(group!-2)!)) *sizeof(array_record));
But i don't know how i create this case. for example what i want if array elements are:
Code:
index value value
0 01 -> 345
1 02 -> 457
2 03 -> 689
3 21 -> 634
so if i have value somewhere 01 match with 01 in this array it display 345. how i can implement it?
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Sep 27, 2014
I'm wondering about the point of pointers to functions. When is it used?I saw the below example. It doesn't make sense to me. I mean we can easily write code that does the same without having to use pointers.
Code:
#include <stdio.h>
int addInt(int a, int b); // Adds 2 integers
int add5to4(int (*function_pointer)(int, int));
int main(void)
{
int sum;
int (*function_pointer)(int, int);
}
[code]....
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Apr 1, 2013
now that I can pick a mesh I want to put it in the ground.So I'm looking for the 3d position of my mouse in the ground.this is my code about picking:
D3DXMATRIX p_matProjection, p_matView, p_matWorld, p_matInverse;
pDevice->GetTransform(D3DTS_PROJECTION,&p_matProjection);
pDevice->GetTransform(D3DTS_VIEW, &p_matView);
pDevice->GetTransform(D3DTS_WORLD, &p_matWorld);
// use the mouse coordinates to get the mouse angle
[code].....
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Aug 17, 2013
Program which accepts two lines and and determines their intersection point and whether they lie within a circle, also given interactively. I'm racing against time and I've racked my skull to no avail
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Jul 9, 2014
I dont see any point of NULL in cstring. The code given below just outputs same as it would have done with NULL. My understanding is if size of char array is less than length of char array then null must be manually added?
#include <iostream>
using namespace std;
int main(){
char chr[0];
cin>>chr;//or if you use cin.getline;
cout<<chr<<endl;
return 0;
}
Enter something: hellowwwww
hellowwwww
Segmentation fault (core dumped)
why? for NULL char or something else?
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Mar 28, 2014
if we have a decimal number like c=3.46
And i want to set two number, a and b
now a= static_type<int>(c); so a=3;
and i want b= 46
which is the two numbers after the decimal how can I do that ? how can I set b = 46 ?
P.S: i do not know what c equals to. now it's two number after the floating point but it might be more or less
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Aug 25, 2013
how can I check if the number is float point number without converting the number to string and then find '.'?
For example, this number (5.0) should not be integer. I found the following way in Python but it didn't work in C++
abs(n - (int)n) < 0.000001
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May 13, 2014
So, I have created a class called "point" and i have 4 "point" objects. They only have 2 variables, x and y (their position). The first 3 points form a triangle and now I need to tell if the forth one is inside or outside. I have found some solutions but they involve heavy math (they are based on the sum of the angles or something like that). I want to know if there is any way to solve this only by using the distance between points. I have created a function which takes 2 "point" objects and returns a float value which is their distance.
Here is some code:
#include <iostream>
#include <cstdlib>
#include <math.h>
using namespace std;
[Code]....
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