Nvidia TX1 TX2 串口通信方法

• 英伟达TX2串口
• • 串口硬件
  • 板子串口描述
  • 硬件连接方式
  • 测试工具及方法
  • c++通信代码

英伟达TX2串口

使用英伟达嵌入式板进行 串口通信 。

串口硬件

串口位置为下图中红色方框位置，标示UARTQ20和J17。

板子串口描述

串口共6个引脚，靠近板子边缘处的第一个为GND引脚，接地；
第四个TX引脚；
第五个RX引脚；

通过USB转接连接到主机Host。

硬件连接方式

使用串口转USB转接器，将TX2引脚与主机USB连接。

测试工具及方法

在linux环境下，分别在Host 和 nvidia device 上使用cutecom:

1. 使用 sudo apt-get install cutecom 即可安装；
2. 安裝完成后，使用 sudo cutecom 启动程序；

启动界面如下图：
说明：

1. . Device: 选择串口名称，Host上串口名称为ttyUSB*命名模式，在英伟达TX2上为ttyTHS2，可修改字符串名字。
2. Settings: 设置波特率等，两者设置相同即可。
3. 点击 Open启动通信。
4. Input后输入内容，将会通过软件送到串口，开始通信。
5. 上部分空白显示串口接收的内容，下方空白显示输入 Input历史。

c++通信代码

包含三个文件，分别为serialport.h、serialport.cpp、main.cpp文件。
serialport.h:

#ifndef BINOCULAR_CUSTOM_SERIALPORT_H#define BINOCULAR_CUSTOM_SERIALPORT_H#include <string>#include <termios.h>#include <vector> struct termios;class SerialPort {public:    enum BaudRate     { BR0 = 0000000, BR50 = 0000001, BR75 = 0000002,BR110 = 0000003, BR134 = 0000004, BR150 = 0000005, BR200 = 0000006,BR300 = 0000007, BR600 = 0000010, BR1200 = 0000011, BR1800 = 0000012, BR2400 = 0000013,BR4800 = 0000014, BR9600 = 0000015, BR19200 = 0000016, BR38400 = 0000017, BR57600 = 0010001,BR115200 = 0010002, BR230400 = 0010003, BR460800 = 0010004, BR500000 = 0010005, BR576000 = 0010006,BR921600 = 0010007, BR1000000 = 0010010, BR1152000 = 0010011, BR1500000 = 0010012, BR2000000 = 0010013,BR2500000 = 0010014, BR3000000 = 0010015, BR3500000 = 0010016, BR4000000 = 0010017 };    enum DataBits { DataBits5, DataBits6, DataBits7, DataBits8, };    enum StopBits { StopBits1, StopBits2 };    enum Parity { ParityNone, ParityEven, PariteMark, ParityOdd, ParitySpace };    struct OpenOptions { bool autoOpen; BaudRate baudRate; DataBits dataBits; StopBits stopBits; Parity parity; bool xon; bool xoff; bool xany; int vmin; int vtime; };    static BaudRate BaudRateMake(unsigned long baudrate);    static const OpenOptions defaultOptions;    explicit SerialPort(const std::string& path, const OpenOptions options = defaultOptions);    bool open();    bool open(const std::string& path, const OpenOptions& options);    bool isOpen() const;    int write(const void *data, int length);    int read(void *data, int length);    void close();    static std::vector<std::string > list();protected:    void termiosOptions(termios& tios, const OpenOptions& options);private:    std::string _path;    OpenOptions _open_options;    int _tty_fd; bool _is_open;};bool operator==(const SerialPort::OpenOptions& lhs, const SerialPort::OpenOptions& rhs);bool operator!=(const SerialPort::OpenOptions& lhs, const SerialPort::OpenOptions& rhs);#endif //BINOCULAR_CUSTOM_SERIALPORT_H

serialport.cpp:

//// Created by yaqiang on 7/22/19.//#include <dirent.h>#include <unistd.h>#include <fcntl.h>#include <termios.h>#include "serialport.h"const SerialPort::OpenOptions SerialPort::defaultOptions = { true, // bool autoOpen;    SerialPort::BR9600, //    BaudRate baudRate;    SerialPort::DataBits8, //    DataBits dataBits;    SerialPort::StopBits1, //    StopBits stopBits;    SerialPort::ParityNone,//    Parity parity;    false, // input xon    false, // input xoff    false, // input xany    0, // c_cc vmin    50, // c_cc vtime }; SerialPort::SerialPort(const std::string &path, const OpenOptions options) : _path(path), _open_options(options){    if(options.autoOpen)    { printf("opening!\n"); _is_open = open(_path, _open_options);    }}bool SerialPort::open(){    return _is_open = open(_path, _open_options), _is_open;}bool SerialPort::open(const std::string &path, const OpenOptions &options){    if(_path != path) _path = path;    if(_open_options != options) _open_options = options;    _tty_fd = ::open(path.c_str(), O_RDWR | O_NOCTTY | O_NONBLOCK);    if(_tty_fd < 0)    { return false;    }    struct termios tios;    termiosOptions(tios, options);    tcsetattr(_tty_fd, TCSANOW, &tios);    tcflush(_tty_fd, TCIOFLUSH); return true;}void SerialPort::termiosOptions(termios &tios, const OpenOptions &options){    tcgetattr(_tty_fd, &tios); tios.c_oflag = 0; tios.c_iflag = 0;    tios.c_lflag = 0; cfsetispeed(&tios, options.baudRate);    cfsetospeed(&tios, options.baudRate); tios.c_iflag |= (options.xon ? IXON : 0) | (options.xoff ? IXOFF: 0) | (options.xany ? IXANY : 0); // data bits    int databits[] = {CS5, CS6, CS7, CS8}; tios.c_cflag &= ~0x30; tios.c_cflag |= databits[options.dataBits]; // stop bits    if(options.stopBits == StopBits2) { tios.c_cflag |= CSTOPB; } else { tios.c_cflag &= ~CSTOPB; } // parity    if(options.parity == ParityNone) { tios.c_cflag &= ~PARENB; } else { tios.c_cflag |= PARENB;    if(options.parity == PariteMark) { tios.c_cflag |= PARMRK; } else { tios.c_cflag &= ~PARMRK; }    if(options.parity == ParityOdd) { tios.c_cflag |= PARODD; } else { tios.c_cflag &= ~PARODD; }    }    tios.c_cc[VMIN] = options.vmin; tios.c_cc[VTIME] = options.vtime;}bool SerialPort::isOpen() const { return _is_open; }int SerialPort::write(const void *data, int length){    return ::write(_tty_fd, data, length);}int SerialPort::read(void *data, int length) { return ::read(_tty_fd, data, length); }void SerialPort::close() { ::close(_tty_fd); _is_open = false; }SerialPort::BaudRate SerialPort::BaudRateMake(unsigned long baudrate){    switch (baudrate)    { case 50: return BR50; case 75: return BR75; case 134: return BR134; case 150: return BR150; case 200: return BR200; case 300: return BR300; case 600: return BR600; case 1200: return BR1200; case 1800: return BR1800; case 2400: return BR2400; case 4800: return BR4800; case 9600: return BR9600; case 19200: return BR19200; case 38400: return BR38400; case 57600: return BR57600; case 115200: return BR115200; case 230400: return BR230400; case 460800: return BR460800; case 500000: return BR500000; case 576000: return BR576000; case 921600: return BR921600; case 1000000: return BR1000000; case 1152000: return BR1152000; case 1500000: return BR1500000; case 2000000: return BR2000000; case 2500000: return BR2500000; case 3000000: return BR3000000; case 3500000: return BR3500000; case 4000000: return BR4000000; default: break;    }    return BR0;}std::vector<std::string> SerialPort::list(){    DIR *dir; struct dirent *ent; dir = opendir("/dev");    std::vector<std::string> ttyList;    while(ent = readdir(dir), ent != nullptr)    { if("tty" == std::string(ent->d_name).substr(0, 3)) {     ttyList.emplace_back(ent->d_name); }    }    return ttyList;}bool operator==(const SerialPort::OpenOptions& lhs, const SerialPort::OpenOptions& rhs){    return lhs.autoOpen == rhs.autoOpen && lhs.baudRate == rhs.baudRate && lhs.dataBits == rhs.dataBits && lhs.parity == rhs.parity && lhs.stopBits == rhs.stopBits && lhs.vmin == rhs.vmin && lhs.vtime == rhs.vtime && lhs.xon == rhs.xon && lhs.xoff == rhs.xoff && lhs.xany == rhs.xany;}bool operator!=(const SerialPort::OpenOptions& lhs, const SerialPort::OpenOptions& rhs){    return !(lhs == rhs);}

main.cpp:

#include "serialport.h"typedef  unsigned char uchar;int main(){   printf("begin!\n");   SerialPort serialPort = SerialPort("/dev/ttyUSB0");   printf("connecting!\n");   serialPort.open();   if(serialPort.isOpen())printf("connected!\n");   else {printf("connect failed!\n");return 0;   }   char* buffer = new char[10];   for(int i=0;i<10;i++)   {buffer[i]='a';   }   printf("begin write!\n");   serialPort.write(buffer,sizeof(char)*10);   printf("write end!\n");//    serialPort.close();//    serialPort.open();//    int* buffer2= new int[10];//    int* buffer2;//    serialPort.read(buffer2,sizeof(int)*10);//    for(int i=0;i<10;i++)//    {// printf("%d \n",buffer2[i]);//    }   serialPort.close();   if(serialPort.isOpen())printf("still connecting!\n");   else {printf("connect closed!\n");return 0;   }   }