Colony

/**

 * Copyright (c) 2007 Colony Project

 * 

 * Permission is hereby granted, free of charge, to any person

 * obtaining a copy of this software and associated documentation

 * files (the "Software"), to deal in the Software without

 * restriction, including without limitation the rights to use,

 * copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following

 * conditions:

 * 

 * The above copyright notice and this permission notice shall be

 * included in all copies or substantial portions of the Software.

 * 

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES

 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,

 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

 * OTHER DEALINGS IN THE SOFTWARE.

 **/

/**

 * @file xbee.c

 * @brief XBee Interface

 *

 * Implementation of low level communication with the XBee in API mode.

 *

 * @author Brian Coltin, Colony Project, CMU Robotics Club

 **/

#include "xbee.h"

#include "wl_defs.h"

#ifndef ROBOT

#include <fcntl.h>

#include <unistd.h>

#include <pthread.h>

#include <errno.h>

#include <termios.h>

#else

#include <serial.h>

#include <avr/interrupt.h>

#endif

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define XBEE_FRAME_START 0x7E

/*Frame Types*/

#define XBEE_FRAME_STATUS 0x8A

#define XBEE_FRAME_AT_COMMAND 0x08

#define XBEE_FRAME_AT_COMMAND_RESPONSE 0x88

#define XBEE_FRAME_TX_REQUEST_64 0x00

#define XBEE_FRAME_TX_REQUEST_16 0x01

#define XBEE_FRAME_TX_STATUS XBEE_TX_STATUS

#define XBEE_FRAME_RX_64 0x80

#define XBEE_FRAME_RX_16 XBEE_RX

/*Internal Function Prototypes*/

/*I/O Functions*/

void xbee_send(char* buf, int size);

void xbee_send_string(char* c);

#ifndef ROBOT

void xbee_read(char* buf, int size);

#endif

/*Command Mode Functions

 * Called during initialization.

 */

void xbee_enter_command_mode(void);

void xbee_exit_command_mode(void);

void xbee_enter_api_mode(void);

void xbee_exit_api_mode(void);

void xbee_wait_for_string(char* s, int len);

void xbee_wait_for_ok(void);

/*API Mode Functions*/

int xbee_handle_packet(char* packet, int len);

void xbee_handle_at_command_response(char* command, char result,

                                     char* extra, int extraLen);

void xbee_handle_status(char status);

int xbee_verify_checksum(char* packet, int len);

char xbee_compute_checksum(char* packet, int len);

void xbee_send_frame(char* buf, int len);

void xbee_send_read_at_command(char* command);

void xbee_send_modify_at_command(char* command, char* value);

/*Global Variables*/

#ifndef ROBOT

char* xbee_com_port = XBEE_PORT_DEFAULT;

int xbee_stream;

pthread_t* xbee_listen_thread;

#endif

// TODO: is this a good size?

#define XBEE_BUFFER_SIZE        256

// a buffer for data received from the XBee

char arrival_buf[XBEE_BUFFER_SIZE];

// location of last unread byte in buffer

volatile int buffer_last = 0;

// first unread byte in buffer

volatile int buffer_first = 0;

//used to store packets as they are read

char xbee_buf[128];

int currentBufPos = 0;

//XBee status

unsigned int xbee_panID = XBEE_PAN_DEFAULT;

unsigned int xbee_pending_panID = XBEE_PAN_DEFAULT;

int xbee_channel = XBEE_CHANNEL_DEFAULT;

int xbee_pending_channel = XBEE_CHANNEL_DEFAULT;

unsigned int xbee_address = 0;

/*Function Implementations*/

#ifdef ROBOT

/**

 * Interrupt for the robot. Adds bytes received from the xbee

 * to the buffer.

 **/

#ifndef FIREFLY

ISR(USART1_RX_vect) {

  char c = UDR1;

  arrival_buf[buffer_last] = c;

  int t = buffer_last + 1;

  if (t == XBEE_BUFFER_SIZE)

    t = 0;

  if (t == buffer_first) {

    WL_DEBUG_PRINT("Out of space in buffer.\n");

  }

  buffer_last = t;

}

#else

SIGNAL(SIG_USART0_RECV) {

  char c = UDR0;

  arrival_buf[buffer_last] = c;

  int t = buffer_last + 1;

  if (t == XBEE_BUFFER_SIZE)

    t = 0;

  if (t == buffer_first) {

    WL_DEBUG_PRINT("Out of space in buffer.\n");

  }

  buffer_last = t;

}

#endif

#else

/**

 * Thread that listens to the xbee.

 **/

void* listen_to_xbee(void* x) {

  char c;

  while (1) {

    xbee_read(&c, 1);

    arrival_buf[buffer_last] = c;

    int t = buffer_last + 1;

    if (t == XBEE_BUFFER_SIZE)

      t = 0;

    if (t == buffer_first) {

      WL_DEBUG_PRINT("Out of space in buffer.\n");

    }

    buffer_last = t;

  }

  return 0;

}

#endif

/**

 * Initializes the XBee library so that other functions may be used.

 **/

int xbee_lib_init(void) {

  arrival_buf[0] = 'A';

  arrival_buf[1] = 'A';

  arrival_buf[2] = 'A';

#ifdef ROBOT

  //enable the receiving interrupt

#ifdef FIREFLY

  UCSR0B |= _BV(RXCIE) | _BV(RXEN);

#else

  UCSR1B |= _BV(RXCIE);

#endif

  sei();

#else

  printf("Connecting to port %s.\n", xbee_com_port);

  xbee_stream = open(xbee_com_port, O_RDWR);

  if (xbee_stream == -1/* || lockf(xbee_stream, F_TEST, 0) != 0*/) {

    printf("Failed to open connection to XBee on port %s\r\n", xbee_com_port);

    return -1;

  }

  // set baud rate, etc. correctly

  struct termios options;

  tcgetattr(xbee_stream, &options);

  cfsetispeed(&options, B9600);

  cfsetospeed(&options, B9600);

  options.c_iflag &= ~ICRNL;

  options.c_oflag &= ~OCRNL;

  options.c_cflag |= (CLOCAL | CREAD);

  options.c_cflag &= ~PARENB;

  options.c_cflag &= ~CSTOPB;

  options.c_cflag &= ~CSIZE;

  options.c_cflag |= CS8;

  options.c_lflag &= ~ICANON;

  options.c_cc[VMIN] = 1;

  options.c_cc[VTIME] = 50;

  if (tcsetattr(xbee_stream, TCSANOW, &options)) {

    fprintf(stderr, "Error setting attributes.\n");

    return -1;

  }

  //lockf(xbee_stream, F_LOCK, 0);

  xbee_listen_thread =

    (pthread_t*)malloc(sizeof(pthread_t));

  if (xbee_listen_thread == NULL) {

    fprintf(stderr, "%s: Malloc failed.\n", __FUNCTION__);

    return -1;

  }

  int ret = pthread_create(xbee_listen_thread, NULL,

                           listen_to_xbee, NULL);

  if (ret) {

    fprintf(stderr, "Failed to create listener thread.\r\n");

    return -1;

  }

#endif

  xbee_enter_command_mode();

  xbee_enter_api_mode();

  xbee_exit_command_mode();

  xbee_send_read_at_command("MY");

  //wait to return until the address is set

  while (xbee_address == 0) xbee_get_packet(NULL);

  return 0;

}

/**

 * Call when finished using the XBee library. This releases

 * all sued resources.

 **/

void xbee_terminate() {

#ifndef ROBOT

  pthread_cancel(*xbee_listen_thread);

  free(xbee_listen_thread);

  lockf(xbee_stream, F_ULOCK, 0);

  close(xbee_stream);

#endif

}

/**

 * Send a buffer buf of size bytes to the XBee.

 * 

 * @param buf the buffer of data to send

 * @param size the number of bytes to send

 **/

void xbee_send(char* buf, int size) {

#ifdef ROBOT

  int i;

  for (i = 0; i < size; i++)

    xbee_putc(buf[i]);

#else

  int ret = write(xbee_stream, buf, size);

  //success

  if (ret == size)

    return;

  if (ret == -1) {

    //interrupted by system signal, probably timer interrupt.

    //just try again

    if (errno == 4) {

      xbee_send(buf, size);

      return;

    }

    printf("Failed to write to xbee, error %i.\r\n", errno);

    return;

  }

  //write was interrupted after writing ret bytes

  xbee_send(buf + ret, size - ret);

#endif

}

/**

 * Sends a string to the XBee.

 *

 * @param c the string to send to the XBEE

 **/

void xbee_send_string(char* c) {

  xbee_send(c, strlen(c));

}

#ifndef ROBOT

void xbee_read(char* buf, int size) {

  if (read(xbee_stream, buf, size) == -1)

    printf("Failed to read from xbee.\r\n");

}

#endif

/**

 * Enter into command mode.

 **/

void xbee_enter_command_mode() {

  xbee_send_string("+++");

  xbee_wait_for_ok();

}

/**

 * Exit from command mode.

 **/

void xbee_exit_command_mode() {

  xbee_send_string("ATCN\r");

  xbee_wait_for_ok();

}

/**

 * Enter API mode.

 **/

void xbee_enter_api_mode() {

  xbee_send_string("ATAP 1\r");

  xbee_wait_for_ok();

}

/**

 * Exit API mode. (warning - does not check for response)

 **/

void xbee_exit_api_mode() {

  xbee_send_string("ATAP 0\r");

}

/**

 * Wait until the string "OK\r" is received from the XBee.

 **/

void xbee_wait_for_ok() {

  xbee_wait_for_string("OK\r", 3);

}

/**

 * Delay until the specified string is received from

 * the XBee. Discards all other XBee data.

 *

 * @param s the string to receive

 * @param len the length of the string

 **/

void xbee_wait_for_string(char* s, int len) {

  char* curr = s;

  while (curr - s < len) {

    // check if buffer is empty

    if (buffer_last == buffer_first)

      continue;

    char c = arrival_buf[buffer_first++];

    if (buffer_first == XBEE_BUFFER_SIZE)

      buffer_first = 0;

    if (c == *curr)

      curr++;

    else

      curr = s;

  }

}

/**

 * Verifies that the packets checksum is correct.

 * (If the checksum is correct, the sum of the bytes

 * is 0xFF.)

 *

 * @param packet the packet received. This includes the first

 * three bytes, which are header information from the XBee.

 *

 * @param len The length of the packet received from the XBee

 *

 * @return 0 if the checksum is incorrect, nonzero

 * otherwise

 **/

int xbee_verify_checksum(char* packet, int len) {

  unsigned char sum = 0;

  int i;

  for (i = 3; i < len; i++)

    sum += (unsigned char)packet[i];

  return sum == 0xFF;

}

/**

 * Returns the checksum of the given packet.

 *

 * @param buf the data for the packet to send

 * @param len the length of the packet in bytes

 *

 * @return the checksum of the packet, which will

 * become the last byte sent in the packet

 **/

char xbee_compute_checksum(char* buf, int len) {

  int i;

  unsigned char sum = 0;

  for (i = 0; i < len; i++)

    sum += (unsigned char)buf[i];

  return 0xFF - sum;

}

/**

 * Adds header information and checksum to the given

 * packet and sends it. Header information includes

 * XBEE_FRAME_START and the packet length, as two bytes.

 *

 * @param buf the packet data

 * @param len the size in bytes of the packet data

 *

 **/

void xbee_send_frame(char* buf, int len) {

  char prefix[3];

  prefix[0] = XBEE_FRAME_START;

  prefix[1] = (len & 0xFF00) >> 8;

  prefix[2] = len & 0xFF;

  char checksum = xbee_compute_checksum(buf, len);

  xbee_send(prefix, 3);

  xbee_send(buf, len);

  xbee_send(&checksum, 1);

}

/**

 * Sends an AT command to read a parameter.

 *

 * @param command the AT command to send. For exmaple,

 * use ID to read the PAN ID and MY to return the XBee ID.

 * See the XBee reference guide for a complete listing.

 **/

void xbee_send_read_at_command(char* command) {

  xbee_send_modify_at_command(command, NULL);

}

/**

 * Sends the given AT command.

 *

 * @param command the AT command to send (e.g., MY, ID)

 * @param value the value to pass as a parameter

 * (or NULL if there is no parameter)

 **/

void xbee_send_modify_at_command(char* command, char* value) {

  char buf[16];

  int i;

  buf[0] = XBEE_FRAME_AT_COMMAND;

  buf[1] = 1;

  buf[2] = command[0];

  buf[3] = command[1];

  int valueLen = 0;

  if (value != NULL) {

    valueLen = strlen(value);

    if (valueLen > 8) {

      WL_DEBUG_PRINT("AT Command too large.\r\n");

      return;

    }

    for (i = 0; i < valueLen; i++)

      buf[4 + i] = value[i];

  }

  xbee_send_frame(buf, 4 + valueLen);

}

/**

 * Send the specified packet.

 * 

 * @param packet the packet data to send

 * @param len the number of bytes in the packet

 * 

 * @param dest the ID of the XBee to send the packet to,

 * or XBEE_BROADCAST to send the message to all robots

 * in the PAN.

 * 

 * @param options a combination of the flags

 * XBEE_OPTIONS_NONE, XBEE_OPTIONS_DISABLE_RESPONSE and 

 * XBEE_OPTIONS_BROADCAST_ALL_PANS

 *

 * @param frame the frame number to associate this packet

 * with. This will be used to identify the response when

 * the XBee alerts us as to whether or not our message

 * was received.

 **/

void xbee_send_packet(char* packet, int len, int dest,

                      char options, char frame) {

  char buf[5];

  char prefix[3];

  int i;

  unsigned char checksum = 0;

  if (len > 100) {

    WL_DEBUG_PRINT("Packet is too large.\r\n");

    return;

  }

  //data for sending request

  buf[0] = XBEE_FRAME_TX_REQUEST_16;

  buf[1] = frame;

  buf[2] = (dest >> 8) & 0xFF;

  buf[3] = dest & 0xFF;

  buf[4] = options;

  //packet prefix, do this here so we don't need an extra buffer

  prefix[0] = XBEE_FRAME_START;

  prefix[1] = ((5 + len) & 0xFF00) >> 8;

  prefix[2] = (5 + len) & 0xFF;

  for (i = 0; i < 5; i++)

    checksum += (unsigned char)buf[i];

  for (i = 0; i < len; i++)

    checksum += (unsigned char)packet[i];

  checksum = 0xFF - checksum;

  xbee_send(prefix, 3);

  xbee_send(buf, 5);

  xbee_send(packet, len);

  xbee_send((char*)&checksum, 1);

}

/**

 * Reads a packet received from the XBee. This function

 * is non-blocking. The resulting packet is stored in dest.

 * Only returns transmission response packets and

 * received packets. The returned packet does not include

 * header information or the checksum. This method also

 * handles special packets dealt with by the XBee library,

 * and so should be called frequently while the XBee is in

 * use.<br><br>

 *

 * The first byte of the packet will be either

 * XBEE_TX_STATUS or XBEE_RX to indicated

 * a response to a sent message or a received message, 

 * respectively.<br><br>

 *

 * For a status response packet:<br>

 * The first byte will be XBEE_TX_STATUS.<br>

 * The second byte will be the frame number.<br>

 * The third byte will be the result. 0 indicates success,

 * and nonzero indicates that an error ocurred in 

 * transmitting the packet.<br><br>

 *

 * For a received packet:<br>

 * The first byte will be XBEE_RX.<br>

 * The second and third bytes will be the 16-bit

 * address of the packet's sender.<br>

 * The fourth byte is the signal strength.<br>

 * The fifth byte is 1 if the packet were sent to

 * a specific address, and 2 if it is a broadcast packet.<br><br>

 * 

 * @param dest set to the packet data

 * @return the length of the packet, or -1 if no packet

 * is available

 **/

int xbee_get_packet(unsigned char* dest) {

  //start reading a packet with XBEE_FRAME_START

  if (currentBufPos == 0) {

    do {

      if (buffer_first == XBEE_BUFFER_SIZE)

        buffer_first = 0;

      // check if buffer is empty

      if (buffer_first == buffer_last)

        return -1;

    }

    while (arrival_buf[buffer_first++] != XBEE_FRAME_START);

    if (buffer_first == XBEE_BUFFER_SIZE)

      buffer_first = 0;

    xbee_buf[0] = XBEE_FRAME_START;

    currentBufPos++;

  }

  int len = -1;

  if (currentBufPos >= 3)

    len = (int)xbee_buf[2] + ((int)xbee_buf[1] << 8);

  while (len == -1 //packet length has not been read yet

         || currentBufPos < len + 4) {

    if (currentBufPos == 3) {

      len = (int)xbee_buf[2] + ((int)xbee_buf[1] << 8);

      if (len > 120) {

        WL_DEBUG_PRINT("Packet too large. Probably error in XBee transmission.\n");

        currentBufPos = 0;

        return -1;

      }

    }

    // check if buffer is empty

    if (buffer_first == buffer_last)

      return -1;

    xbee_buf[currentBufPos++] = arrival_buf[buffer_first++];

    if (buffer_first == XBEE_BUFFER_SIZE)

      buffer_first = 0;

  }

  currentBufPos = 0;

  if (!xbee_verify_checksum(xbee_buf, len + 4)) {

    WL_DEBUG_PRINT("XBee checksum failed.\r\n");

    return -1;

  }

  //we will take care of the packet

  if (xbee_handle_packet(xbee_buf + 3, len))

    return -1;

  if (dest == NULL)

    return -1;

  int i;

  for (i = 3; i < len + 3; i++)

    dest[i - 3] = xbee_buf[i];

  return len;

}

/**

 * Handles modem status packets.

 *

 * @param status the type of status packet received.

 **/

void xbee_handle_status(char status) {

  switch (status) {

  case 0:

    WL_DEBUG_PRINT("XBee hardware reset.\r\n");

    break;

  case 1:

    WL_DEBUG_PRINT("Watchdog timer reset.\r\n");

    break;

  case 2:

    WL_DEBUG_PRINT("Associated.\r\n");

    break;

  case 3:

    WL_DEBUG_PRINT("Disassociated.\r\n");

    break;

  case 4:

    WL_DEBUG_PRINT("Synchronization lost.\r\n");

    break;

  case 5:

    WL_DEBUG_PRINT("Coordinator realignment.\r\n");

    break;

  case 6:

    WL_DEBUG_PRINT("Coordinator started.\r\n");

    break;

  }

}

/**

 * Handles AT command response packets.

 * @param command the two character AT command, e.g. MY or ID

 * @param result 0 for success, 1 for an error

 * @param extra the hex value of the requested register

 * @param extraLen the length in bytes of extra

 **/

void xbee_handle_at_command_response(char* command, char result,

                                     char* extra, int extraLen) {

  if (result == 1) {

    WL_DEBUG_PRINT("Error with AT");

    WL_DEBUG_PRINT(command);

    WL_DEBUG_PRINT(" packet.\r\n");

  }

  WL_DEBUG_PRINT("AT");

  WL_DEBUG_PRINT(command);

  WL_DEBUG_PRINT(" command was successful.\r\n");

  if (command[0] == 'I' && command[1] == 'D') {

    xbee_panID = xbee_pending_panID;

    WL_DEBUG_PRINT("PAN ID set to ");

    WL_DEBUG_PRINT_INT(xbee_panID);

    WL_DEBUG_PRINT(".\r\n");

    return;

  }

  if (command[0] == 'C' && command[1] == 'H') {

    xbee_channel = xbee_pending_channel;

    WL_DEBUG_PRINT("Channel set to ");

    WL_DEBUG_PRINT_INT(xbee_channel);

    WL_DEBUG_PRINT(".\r\n");

    return;

  }

  if (command[0] == 'M' && command[1] == 'Y' && extraLen != 0) {

    xbee_address = 0;

    int i;

    for (i = 0; i < extraLen; i++)

      xbee_address = (xbee_address << 8) + extra[i];

    WL_DEBUG_PRINT("XBee address is ");

    WL_DEBUG_PRINT_INT(xbee_address);

    WL_DEBUG_PRINT(".\r\n");

    if (xbee_address == 0) {

      WL_DEBUG_PRINT("XBee 16-bit address must be set using ATMY.\r\n");

      exit(0);

    }

  }

}

/**

 * Attempts to handle the packet if it is dealt with

 * by the library.

 * We will handle the following packet types:

 *    Modem Status

 *    AT Command Response

 *

 * @param packet the packet to handle

 * @param len the length of the packet

 * 

 * @return 1 if we have handled the packet, 0 otherwise

 */

int xbee_handle_packet(char* packet, int len) {

  char command[3] = {1, 2, 3};

  if (len <= 0) {

    //this should not happend

    WL_DEBUG_PRINT("Non-positive packet length.\r\n");

    return 0;

  }

  //packet type

  switch ((unsigned char)packet[0]) {

  case XBEE_FRAME_STATUS:

    xbee_handle_status(packet[1]);

    return 1;

  case XBEE_FRAME_AT_COMMAND_RESPONSE:

    command[0] = packet[2];

    command[1] = packet[3];

    command[2] = 0;

    xbee_handle_at_command_response(command,

                                    packet[4], packet + 5, len - 5);

    return 1;

  }

  return 0;

}

/**

 * Sets the personal area network id.

 *

 * @param id the new personal area network (PAN) id

 **/

void xbee_set_pan_id(int id) {

  char s[3];

  s[0] = (id >> 8) & 0xFF;

  s[1] = id & 0xFF;

  s[2] = 0;

  xbee_pending_panID = id;

  xbee_send_modify_at_command("ID", s);

}

/**

 * Get the PAN ID for the XBee.

 * 

 * @return the personal area network id, or

 * XBEE_PAN_DEFAULT if it has not yet been set.

 **/

unsigned int xbee_get_pan_id() {

  return xbee_panID;

}

/**

 * Set the channel the XBee is using.

 *

 * @param channel the channel the XBee will not use, 

 * between 0x0B and 0x1A

 *

 * @see xbee_get_channel

 **/

void xbee_set_channel(int channel) {

  if (channel < 0x0B || channel > 0x1A) {

    WL_DEBUG_PRINT("Channel out of range.\r\n");

    return;

  }

  char s[3];

  s[0] = channel & 0xFF;

  s[1] = 0;

  xbee_pending_channel = channel;

  xbee_send_modify_at_command("CH", s);

}

/**

 * Returns the channel which the XBee is currently using.

 *

 * @return the channel the XBee is using

 *

 * @see xbee_set_channel

 **/

int xbee_get_channel(void) {

  return xbee_channel;

}

/**

 * Get the 16-bit address of the XBee.

 * This is used to specify who to send messages to

 * and who messages are from.

 *

 * @return the 16-bit address of the XBee.

 **/

unsigned int xbee_get_address() {

  return xbee_address;

}

#ifndef ROBOT

void xbee_set_com_port(char* port) {

  xbee_com_port = port;

}

#endif