configure UART1 for using hardware flow control in Linux

Hi all!

On custom board, based on DM816x EVM, I have UART1 connected to the ADM3078EARZ (http://pdf1.alldatasheet.net/datasheet-pdf/view/164508/AD/ADM3078EARZ.html). I wrote test application to check that data is transmitted. I see (by oscilloscope) data on UART1_TXD line, but I can not see what RTS line is driven (RTS connected to the DE on ADM3078) and data not be transmitted. I use default linux kernel and MUX settings for UART1 from EZSDK_5_04_00_11.

Please tell me how I can drive RTS line to enable DE signal on ADM3078EARZ?

May be I have error in test application, or need additional MUX settings for CTS/RTS pins?

Thank you.

Application File: 5008.main.cpp

usage: ./app /dev/ttyO1

My application code: 

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <termios.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <sys/types.h>

//-----------------------------------------------------------------------------

#define BUF_SIZE 4

//-----------------------------------------------------------------------------

volatile int exit_flag = 0;

//-----------------------------------------------------------------------------

void exit_app(int sig)
{
 exit_flag = 1;
}

//-----------------------------------------------------------------------------

int main(int argc, char *argv[])
{
 int err = 0;
 
 signal(SIGINT, exit_app);
 
 if(argc == 1) {
 printf("usage: %s <device name>\n", argv[0]);
 return -1;
 }

printf("Start testing device %s\n", argv[1]);
 
 int fd = open(argv[1], O_RDWR | O_NOCTTY | O_NDELAY);
 if(fd < 0) {
 fprintf(stderr, "%s(): Error open device %s\n", __FUNCTION__, argv[1]);
 return fd;
 }
 
 printf("Open device %s\n",argv[1]);

 struct termios options;

 tcgetattr(fd, &options);

 cfsetispeed(&options, B115200);
 cfsetospeed(&options, B115200);

 options.c_cflag &= ~PARENB;
 options.c_cflag &= ~CSTOPB;
 options.c_cflag &= ~CSIZE;
 options.c_cflag |= CS8;
 options.c_cc[VMIN] = 0;
 options.c_cc[VTIME] = 1;
 options.c_cflag |= (CLOCAL | CREAD | CRTSCTS);

 if(tcsetattr(fd, TCSANOW, &options)!= 0) {

 printf("Error setup serial port\n");
 close(fd);
 return -1;
 }

 unsigned char outBuf[BUF_SIZE];
 unsigned char inBuf[BUF_SIZE];
 
 for(int i=0; i<BUF_SIZE; i++) {
 outBuf[i] = i;
 inBuf[i] = 0;
 }
 
 do {
 
 printf("Press Enter to write data\n");
 getchar();
 
 if(exit_flag) {
 break;
 }
 
 err = write(fd, outBuf, sizeof(outBuf));
 if(err < 0) {
 printf("Error write device: %s\n", strerror(errno));
 break;
 } else {
 printf("Write %d bytes\n", err);
 }
 
 } while (1);

 close(fd);

 return err;
}