Re: [ts-7000] TS7260-Reading from /dev/ttyUSB0

[Alexey Vdovin <>]

Tsao,

In function receivePacket try read more then 1 byte at once:

unsigned char temp = read(fd, buffer+i, left_to_read);
i += temp;
left_to_read -= temp;

To avoid hangs add read timeout to this function.
Keep in mind, some date bytes may be lost or corrupted during 
transmission, you need error checking mechanism.

---
Best Regards
Alexey Vdovin

-----Original Message-----
From: "tsao.terence" <>
To: 
Date: Thu, 04 Mar 2010 08:44:03 -0000
Subject: [ts-7000] TS7260-Reading from /dev/ttyUSB0

> Dear Linux masters,
> 
>      I am communicating TS7260 with my sensor device using a USB to serial 
> FTDI converter.  The sensor uses the uart interface, and the TS7260 uses the 
> USB interface.  The sensor device will send TS7260 a packet of data which 
> contains 512 bytes, aka each packet is 512 bytes.
> 
> 
> I had success reading from ttyUSB0 with 9600 and 38400 baudrate, but when I 
> jump to 57600 baud, the program just hangs.  I think there might be something 
> wrong as I open the USB port, or my receive function has too much software 
> overhead.  Anyone here had success reading from the ttyUSB0 port?
> 
> Here is my open USB function:
> int openUSB()
> {
>     int fd = open ("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY | O_FSYNC);
>     if (fd==-1)
>     {
>       fprintf(stderr, "open_port: Unable to open /dev/ttyUSB0 -%s \n",
>                strerror(errno));
>     }
> 
>     struct termios options;
> 
>     /*Configure port reading*/
>     fcntl (fd, F_SETFL, FNDELAY);
>     /*Get the current options for the port*/
>     tcgetattr(fd, &options);
> 
>     /*Set baudrate to 500000Mb*/
>     cfsetispeed(&options, B57600);
>     cfsetospeed(&options, B57600);
> 
>     /*Mark the character size to 8 bits, no parity*/
>     options.c_cflag     |= (CLOCAL | CREAD);
>     options.c_lflag     &= ~(ICANON | ECHO | ECHOE | ISIG);
>     options.c_oflag     &= ~OPOST;
>     options.c_iflag     &= ~(IXON | ICRNL);
>     options.c_cc[VMIN]  = 0;
>     options.c_cc[VTIME] = 0;
>     tcsetattr(fd, TCSANOW, &options);
>     return fd;
> }
> 
> Here is my read function:.
> unsigned char receivePacket(int fd, unsigned char *buffer)
> {
> 
>     unsigned int i=0;
>     unsigned int left_to_read=520;
>     unsigned char byte;
>     while(left_to_read>0)
>     {
>      nsigned char temp = read(fd, &byte, 1);
>      if(temp>0)
>      {
>       left_to_read--;
>       buffer[i]=byte;
>       printf("%.2x",byte);
>       i++;
>      }
>     }
>     return 0;
> }
> 



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