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您好,使用OMAPL138-EVM开发板,按照《2-1开发板快速体验》,在内核编译时把"System Type -> TI DaVinci Implementations->Enable UART1 RS485 funcation"选项选上,并重新编译内核,然后使用编译后的内核启动系统。发现开发板485口能发数据,但是不能接收数据。
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/ Y0 W; b @' q我的qt程序如下:7 n0 h% x; f5 G/ y9 s
struct termios setting;
# q" ?" v5 h. x fd = open("/dev/ttyS1", O_RDWR);
z1 K/ g5 a( x k& n if (fd == -1) {
: }' q0 i0 |, h+ z. X LOG_INFO("open /dev/ttyS failure ...");0 q3 t. O* w9 x$ n8 u* D
return ;) O& w9 d: h9 y
}
& H$ q" t7 b* k1 H( u LOG_INFO("open /dev/ttyS1 success ...");
! U0 g2 A) f. f tcgetattr(fd, &setting);, k* R1 e5 e/ v
speed_t speed; [/ a. u- W8 y3 G; ^7 w9 {$ V W/ Q
speed = btr;
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( t* L1 ~* a, Y4 G! F cfsetispeed(&setting, speed);, t9 ~' h; O4 ?1 V1 \; P
cfsetospeed(&setting, speed);
6 n9 N9 F% I, T1 Y a6 r& l cfmakeraw(&setting);
" n. E3 D' `" S; Y d2 i7 P! \ setting .c_cflag |= CS8;$ r" K5 r1 U1 m. |0 a
setting.c_cflag &= ~PARENB;
" L/ Q6 J, v: q" A8 j4 X M& |/ V setting.c_iflag &= ~INPCK;
# R5 }$ U; l' v/ w- y, V9 N% I- ] setting.c_cflag &= ~CSTOPB;
9 q& y0 j' v. o5 C! ^ tcflush(fd, TCIFLUSH);
- r/ J6 z9 g% v4 ^ setting.c_cc[VTIME] = 0;
6 H! s4 H, j4 d$ r+ ? setting.c_cc[VMIN] = 0;. A; z0 A( J. I% B1 }% i( s
tcsetattr(fd, TCSANOW, &setting);& r. [, N K+ X
. ]" W P. f, v, Y( t int ret;
: C* ~8 v2 n* g6 A; D( @ char *buff = {"hello,485write ok"} ;
( f; H5 X& T! q3 P7 z ret = write(fd, buff, 17);; o3 W8 f" q9 Y
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char buff1[256] ;
( k& |2 n% Q: r while(1){
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ret = read(fd, buff1, 255);/ P0 H; i: ^+ s) G2 N: K/ Y
if(ret > 0){: X; O& l% x! h$ M" `) [
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write(fd, buff1, 5);- D" O) {8 L# Z
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LOG_INFO("rs485 receiver ret = %d " , ret);* t/ u( I2 ^/ H2 b6 D( M( q
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我使用串口调试助手,开发板能发送数据,调试助手能收到”hello,485write ok“,但是调试助手发的数据开发板却没有收到。并且用示波器可以看到UART1_RXD管脚的数据。请问为什么?
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