/***********************************************************************************
* am335x Qt SocketCAN Demo hacking
* 说明：
* 本源代码来自OK335xS，主要是为分析如何在Qt中使用SocketCAN的这种通信方式。
*
* 2015-9-12 晴 深圳 南山平山村 曾剑锋
**********************************************************************************/
cat main.c
#include <QtGui/QApplication>
#include "mainwindow.h"
#include "myinputpanelcontext.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
/**
* 创建软键盘
*/
MyInputPanelContext *ic = new MyInputPanelContext;
/**
* This function replaces the QInputContext instance used by the application with inputContext.
* Qt takes ownership of the given inputContext.
*
* 设置软键盘
*/
a.setInputContext(ic); //将输入上下文与应用程序关联
MainWindow w;
/**
* Qt::WindowMaximizeButtonHint:
* Adds a maximize button. On some platforms this implies Qt::WindowSystemMenuHint for it to work.
* Qt::WindowMinimizeButtonHint:
* Adds a minimize button. On some platforms this implies Qt::WindowSystemMenuHint for it to work.
*/
w.setWindowFlags(w.windowFlags()& ~Qt::WindowMaximizeButtonHint& ~Qt::WindowMinimizeButtonHint);
w.showMaximized();
w.show();
return a.exec();
}
cat mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QProcess>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/can.h>
#include "thread.h"
#include <QButtonGroup>
/**
* 引入界面文件生成的UI类
*/
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
protected:
void moveEvent(QMoveEvent *); // 界面移动事件
void resizeEvent(QResizeEvent *); // 界面重绘大小事件
void closeEvent(QCloseEvent *); // 界面关闭事件
private slots:
void on_send_clicked(); // 发送按钮点击槽
void msg(QString str); // 信息处理信号槽
void stopcan(int v); // 停止can信号槽
void startcan(int v); // 开始can信号槽
void on_can0_toggled(bool checked); // can0 被点击翻转信号槽
void on_can1_toggled(bool checked); // can1 被点击翻转信号槽
private:
Ui::MainWindow *ui; // 声明图形界面指针
int socket; // can socket 描述符
struct sockaddr_can addr; // can socket 地址结构体
Thread *t; // 线程
QButtonGroup* btg; // 按钮
};
#endif // MAINWINDOW_H
cat mainwindow.c
#include <sys/ioctl.h>
#include <fcntl.h>
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>
#include <unistd.h>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent), // 构造函数初始化父类构造函数
ui(new Ui::MainWindow) // 创建ui实体，并赋值
{
ui->setupUi(this); // 设置将图形界面放置在哪个对象上
btg = new QButtonGroup; // 创建分组，多选一
btg->addButton(ui->can0,0);
btg->addButton(ui->can1,1);
startcan(0);
}
MainWindow::~MainWindow()
{
/**
* 这里让人怀疑，都已经删除了ui界面，button group又怎么能够获取到ui里面的checkedId呢？
* 唯一的解释就是button group里面保存了最后一次toggle事件获取的checkedId值，而不是运行
* checkedId()的时候去获取checkedId
*/
delete ui;
stopcan(btg->checkedId());
}
void MainWindow::msg(QString str)
{
/**
* 将获取到的信息放到显示文本框的最后去
*/
ui->label->append(str);
}
void MainWindow::on_send_clicked()
{
/**
* struct can_frame - basic CAN frame structure
* @can_id: CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition
* @can_dlc: frame payload length in byte (0 .. 8) aka data length code
* N.B. the DLC field from ISO 11898-1 Chapter 8.4.2.3 has a 1:1
* mapping of the 'data length code' to the real payload length
* @data: CAN frame payload (up to 8 byte)
*
* struct can_frame {
* canid_t can_id; // 32 bit CAN_ID + EFF/RTR/ERR flags
* __u8 can_dlc; // frame payload length in byte (0 .. CAN_MAX_DLEN)
* __u8 data[CAN_MAX_DLEN] __attribute__((aligned(8)));
* };
*/
struct can_frame frame;
/**
* 获取将要发送的文本内容
* Returns a std::string object with the data contained in this QString.
* The Unicode data is converted into 8-bit characters using the toUtf8() function.
*/
std::string str=ui->edit->text().toStdString();
/**
* 如果文本的长度大于8，那么将给出提示信息，并直接返回，不发送数据
*/
if(str.length() > 8)
{
QMessageBox::about(this,"error","length of send string must less than 8 bytes");
return;
}
/**
* 默认发送的can id是0x123
*
* 扩展格式识别符由 29 位组成。其格式包含两个部分：11 位基本 ID、18 位扩展 ID。
* Controller Area Network Identifier structure:
*
* bit 0-28 : CAN识别符 (11/29 bit)
* bit 29 : 错误帧标志 (0 = data frame, 1 = error frame)
* bit 30 : 远程发送请求标志 (1 = rtr frame)
* bit 31 : 帧格式标志 (0 = standard 11 bit, 1 = extended 29 bit)
*
* typedef __u32 canid_t;
*
* struct can_frame {
* canid_t can_id; // 32 bit CAN_ID + EFF/RTR/ERR flags
* __u8 can_dlc; // 数据长度: 0 .. 8
* __u8 data[8] __attribute__((aligned(8)));
* };
*/
frame.can_id = 0x123;
/**
* Returns a pointer to an array that contains a null-terminated sequence of
* characters (i.e., a C-string) representing the current value of the string object.
* This array includes the same sequence of characters that make up the value of
* the string object plus an additional terminating null-character ('\0') at the end.
*/
strcpy((char*)frame.data, str.c_str());
/**
* 目前猜测：dlc --> data length count
* 于是可以很好的解释：can 发送的数据长度，是按字节算的
*/
frame.can_dlc = str.length();
/**
* Send N bytes of BUF on socket FD to peer at address ADDR (which is
* ADDR_LEN bytes long). Returns the number sent, or -1 for errors.
*
* This function is a cancellation point and therefore not marked with
* __THROW.
*
* extern ssize_t sendto (int __fd, __const void *__buf, size_t __n,
* int __flags, __CONST_SOCKADDR_ARG __addr,
* socklen_t __addr_len);
*/
sendto(socket,&frame,sizeof(struct can_frame),0,(struct sockaddr*)&addr,sizeof(addr));
}
void MainWindow::moveEvent(QMoveEvent *)
{
/**
* 让测试窗口不会被移动
*/
this->move(QPoint(0,0));
}
void MainWindow::resizeEvent(QResizeEvent *)
{
/**
* 让窗口最大化显示
*/
this->showMaximized();
}
void MainWindow::closeEvent(QCloseEvent *)
{
/**
* 直接退出，不用关闭can口么？也就是说程序会在真正推出前，先解析掉所有当前生成的类实体？
*/
exit(0);
}
void MainWindow::startcan(int v)
{
/**
* 从提示信息可以看出，使用125000作为默认的波特率
*/
if(v == 0)
{
system("canconfig can0 bitrate 125000 ctrlmode triple-sampling on");
system("canconfig can0 start");
}
else
{
system("canconfig can1 bitrate 125000 ctrlmode triple-sampling on");
system("canconfig can1 start");
}
/**
* Create a new socket of type TYPE in domain DOMAIN, using
* protocol PROTOCOL. If PROTOCOL is zero, one is chosen automatically.
* Returns a file descriptor for the new socket, or -1 for errors.
*
* extern int socket (int __domain, int __type, int __protocol) __THROW;
*
* #define PF_CAN 29 // Controller Area Network.
*
* SOCK_RAW = 3, // Raw protocol interface.
* #define SOCK_RAW SOCK_RAW
*
* particular protocols of the protocol family PF_CAN
* #define CAN_RAW 1 // RAW sockets
*
*/
socket = ::socket(PF_CAN, SOCK_RAW, CAN_RAW);
/**
* struct ifreq
* {
* # define IFHWADDRLEN 6
* # define IFNAMSIZ IF_NAMESIZE
* union
* {
* char ifrn_name[IFNAMSIZ]; // Interface name, e.g. "en0".
* } ifr_ifrn;
*
* union
* {
* struct sockaddr ifru_addr;
* struct sockaddr ifru_dstaddr;
* struct sockaddr ifru_broadaddr;
* struct sockaddr ifru_netmask;
* struct sockaddr ifru_hwaddr;
* short int ifru_flags;
* int ifru_ivalue;
* int ifru_mtu;
* struct ifmap ifru_map;
* char ifru_slave[IFNAMSIZ]; // Just fits the size
* char ifru_newname[IFNAMSIZ];
* __caddr_t ifru_data;
* } ifr_ifru;
* };
* # define ifr_name ifr_ifrn.ifrn_name // interface name
* # define ifr_hwaddr ifr_ifru.ifru_hwaddr // MAC address
* # define ifr_addr ifr_ifru.ifru_addr // address
* # define ifr_dstaddr ifr_ifru.ifru_dstaddr // other end of p-p lnk
* # define ifr_broadaddr ifr_ifru.ifru_broadaddr // broadcast address
* # define ifr_netmask ifr_ifru.ifru_netmask // interface net mask
* # define ifr_flags ifr_ifru.ifru_flags // flags
* # define ifr_metric ifr_ifru.ifru_ivalue // metric
* # define ifr_mtu ifr_ifru.ifru_mtu // mtu
* # define ifr_map ifr_ifru.ifru_map // device map
* # define ifr_slave ifr_ifru.ifru_slave // slave device
* # define ifr_data ifr_ifru.ifru_data // for use by interface
* # define ifr_ifindex ifr_ifru.ifru_ivalue // interface index
* # define ifr_bandwidth ifr_ifru.ifru_ivalue // link bandwidth
* # define ifr_qlen ifr_ifru.ifru_ivalue // queue length
* # define ifr_newname ifr_ifru.ifru_newname // New name
* # define _IOT_ifreq _IOT(_IOTS(char),IFNAMSIZ,_IOTS(char),16,0,0)
* # define _IOT_ifreq_short _IOT(_IOTS(char),IFNAMSIZ,_IOTS(short),1,0,0)
* # define _IOT_ifreq_int _IOT(_IOTS(char),IFNAMSIZ,_IOTS(int),1,0,0)
*
* SIOCGIFINDEX:
* Retrieve the interface index of the interface into ifr_ifindex.
*/
struct ifreq ifr;
strcpy((char *)(ifr.ifr_name),v == 0 ? "can0" : "can1");
ioctl(socket,SIOCGIFINDEX,&ifr);
/**
* 绑定socket
*/
addr.can_family = AF_CAN;
addr.can_ifindex = ifr.ifr_ifindex;
bind(socket,(struct sockaddr*)&addr,sizeof(addr));
/**
* 这里是存在问题，每次线程并没有关闭，而是直接不管，可能导致一些问题
* 从后续的代码可以看出，每次都已经停止了线程，delete了对象实体。
*/
t = NULL;
/**
* 创建线程，并将socket文件描述符作为参数传入线程，主要作为接受数据线程
*/
t = new Thread(socket);
/**
* 用于处理线程发出的信号
*/
connect(t,SIGNAL(msg(QString)),this,SLOT(msg(QString)));
/**
* 开启线程
*/
t->start();
}
void MainWindow::stopcan(int v)
{
/**
* 关闭对应的can之前，先关闭对应socket接受线程
*/
if(t)
{
t->stop();
t->deleteLater();
}
/**
* 关闭socket文件描述符
*/
::close(socket);
/**
* 给出相关的提示信息
*/
if(v == 0)
system("canconfig can0 stop");
else
system("canconfig can1 stop");
}
void MainWindow::on_can0_toggled(bool checked)
{
/**
* 根据对应的情况，打开，或者关闭对应的can设备
*/
if(checked)
{
stopcan(1);
startcan(0);
}
}
void MainWindow::on_can1_toggled(bool checked)
{
/**
* 根据对应的情况，打开，或者关闭对应的can设备
*/
if(checked)
{
stopcan(0);
startcan(1);
}
}
