serial.c

serial.c

// serial.c
// -----------------------------------------------------------------------

#include <fcntl.h>
#include <termios.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <stdbool.h>
#include <errno.h>
#include <stdio.h>
#include <pthread.h>
#include <sys/signal.h>

#include "h/xb_log.h"
#include "h/debug.h"
#include "h/circular.h"

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

#define BAUDRATE B9600
#define DEVICE "/dev/ttyAMA0"

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

static int read_fd;
static int write_fd;
static struct termios tty;
static pthread_t rx_thread;

// -----------------------------------------------------------------------
// return true if there is any serial data available for reading

bool serial_available(void)
{
  int c = circular_count();
  return(0 != c);
}

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

uint8_t serial_read(void)
{
  uint8_t c;

  while(!serial_available())
    ;

  c = circular_get();
  return c;
}

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

int serial_write(uint8_t *p, uint8_t n)
{
  int z;
  for(;;)
  {
    z = write(write_fd, p, n);
    if(!(z < 0))
    {
      break;
    }
    usleep(50);
  }
  return z;
}

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

int serial_writec(uint8_t c)
{
  int cc;

  for(;;)
  {
    cc = serial_write(&c, 1);
    if(!(cc < 0))
    {
      break;
    }
    usleep(50);
  }
  return cc;
}

// -----------------------------------------------------------------------
// copy data into circular buffer after a read

static void copy_data(uint8_t *p, uint8_t n)
{
  int i;

  for(i = 0; i < n; i++)
  {
    circular_put(p[i]);
  }
}

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

void *rx_handler(void *p)
{
  int res;
  uint8_t tmp[256];

  for(;;)
  {
    for(;;)
    {
      res = read(read_fd, &tmp[0], 255);
      if(0 != res)
      {
        break;
      }
      usleep(100);
    }

    if(res == -1)
    {
      xb_log("serial", "Read Error %d", errno);
      usleep(100);
      continue;
    }
    else  if(0 == res)
    {
      xb_log("serial", "Read returned with zero bytes wtf");
    }
    tmp[res] = 0;

printf("%s\n", tmp);
#ifdef DEBUG
    xb_log("serial", "rx = %s", tmp);
#endif

    copy_data(&tmp[0], res);
  }
  return NULL;
}

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

#define C_CFLAG (CS8 | CLOCAL | CREAD)
#define C_LFLAG (ECHO | ISIG | ECHOE | ICANON)

void tty_init(int fd)
{
  tcgetattr(fd, &tty);

  cfsetispeed(&tty, BAUDRATE);
  cfsetospeed(&tty, BAUDRATE);

  tty.c_cflag &= ~(PARENB | CSIZE | CRTSCTS);
  tty.c_cflag |= C_CFLAG;

  tty.c_iflag &= ~(IXOFF | IXANY | IXON);
  tty.c_iflag |= (IGNPAR | ICRNL | ONLCR);

  tty.c_oflag = 0;
  tty.c_lflag &= ~C_LFLAG;

  tty.c_cc[VMIN] = 1;
  tty.c_cc[VTIME] = 5;

  tcsetattr(fd, TCSANOW, &tty);
  usleep(100);
}

// -----------------------------------------------------------------------
// initialize serial comms to xbee module

void init_serial(void)
{
  read_fd = open(DEVICE, O_RDONLY | O_NOCTTY);

  if(read_fd < 0)
  {
    xb_log("serial", "Failed To Open Serial Port for Read");
    exit(-1);
  }

  write_fd = open(DEVICE, O_WRONLY | O_NOCTTY);

  if(write_fd < 0)
  {
    xb_log("serial", "Failed To Open Serial Port for Write");
    exit(-1);
  }

  tcflush(read_fd, TCIFLUSH);
  tcflush(write_fd, TCOFLUSH);

  tty_init(read_fd);  // this configures the port, not the fd

  if(0 != pthread_create(&rx_thread, NULL, &rx_handler, NULL))
  {
    xb_log("serial", "Failed to create RX Thread");
    exit(-1);
  }
}

// =======================================================================