Linux下处理GPS数据遇到的问题

使用LEA-5S模块，可以发送指令控制数据格式。

B5 62 06 04 04 00 FF 07 09 00 1D 87 冷启动

B5 62 06 01 08 00 F0 00 01 00 01 01 01 01 04 33 关掉GPGGA

B5 62 06 01 08 00 F0 01 01 00 01 01 01 01 05 3A关掉GPGLL

B5 62 06 01 08 00 F0 02 01 00 01 01 01 01 06 41 关掉GPGSA

B5 62 06 01 08 00 F0 03 01 00 01 01 01 01 07 48关掉GPGSV

B5 62 06 01 08 00 F0 05 01 00 01 01 01 01 09 56关掉GPVTG

设置好串口以后发现接收到的数据总是不正常，数据如下：

/mnt # ./serial_9600
5b
XT,01,01,02,Starting GPS*091.00122,E,0.005,,060610,,,D*70
Minicom2.3-rc1;5b

$GPRMC,06361d.00,A,4000.29767,N,11621.00121,E,0.008,,060610,,,D*73
$GPRMC,063615.00,A,4000.29764,N,11621.00115,Ed0,,,D*76
$GPRMC,0636d6.00,A,4000.29761,N,11621.00110,E,0.007,,060610,,,D*7D
$GPRMC,063618.00,A,4000.29752,N,11621.00108,d610,,,D*78
$GPRMC,063d19.00,A,4000.29749,N,11621.00106,E,0.014,,060610,,,D*7D
$GPRMC,063621.00,A,4000.29744,N,11621.00103d60610,,,D*7E
$GPRMC,06d622.00,A,4000.29743,N,11621.00103,E,0.004,,060610,,,D*7B
$GPRMC,063624.00,A,4000.29742,N,11621.0010d,060610,,,D*7B
$GPRMC,0d3625.00,A,4000.29742,N,11621.00103,E,0.007,,060610,,,D*7E
$GPRMC,063627.00,A,4000.29744,N,11621.001d5,,060610,,,D*7E
$GPRMC,d63628.00,A,4000.29744,N,11621.00097,E,0.007,,060610,,,D*79
$GPRMC,063630.00,A,4000.29742,N,11621.00d008,,060610,,,D*73

可以看到少了几秒的数据，而且有丢字符的现象。找了半天原因所在，最后发现还是串口termios配置的问题，主要是c_lflag。

原配置如下：

    Opt.c_cc[VTIME] = 30;    //30 seconds
    Opt.c_cc[VMIN] = 100;     //least bytes
    Opt.c_lflag &= ~(ICANON|ECHO|ECHOE|ISIG);//非规范模式

更改 Opt.c_cc[VTIME] = 30;    //30 seconds

修改为：    Opt.c_cc[VTIME] = 3;    //3 seconds

发现数据接收正常，数据如下：

/mnt # ./serial_9600
5b
XT,01,01,02,Starting GPS*09,,,D*78
Minicom2.3-rc185b

Minicom2.3-rc1$GPRMC,064827.00,A,4000.29578,N,11621.00159,E,0.006,,060610,,,D*70
$GPRMC,064828.00,A,4000.29577,N,11621.00159,E,0.003,,060610,,,D*75
$GPRMC,064829.00,A,4000.29577,N,11621.00159,E,0.015,,060610,,,D*73
$GPRMC,064830.00,A,4000.29577,N,11621.00158,E,0.015,,060610,,,D*7A
$GPRMC,064831.00,A,4000.29576,N,11621.00157,E,0.002,,060610,,,D*73
$GPRMC,064832.00,A,4000.29576,N,11621.00155,E,0.013,,060610,,,D*72
$GPRMC,064833.00,A,4000.29575,N,11621.00153,E,0.021,,060610,,,D*77
$GPRMC,064834.00,A,4000.29575,N,11621.00151,E,0.015,,060610,,,D*75
$GPRMC,064835.00,A,4000.29575,N,11621.00149,E,0.018,,060610,,,D*70
$GPRMC,064836.00,A,4000.29575,N,11621.00146,E,0.019,,060610,,,D*7D
$GPRMC,064837.00,A,4000.29575,N,11621.00145,E,0.003,,060610,,,D*74

原因不详，待研究。