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XBee packet I/O (linux)
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include "xbee.h"
static unsigned int bitrate_conversion[][2] = {
{ 50, B50 },
{ 75, B75 },
{ 110, B110 },
{ 134, B134 },
{ 150, B150 },
{ 200, B200 },
{ 300, B300 },
{ 600, B600 },
{ 1200, B1200 },
{ 1800, B1800 },
{ 2400, B2400 },
{ 4800, B4800 },
{ 9600, B9600 },
{ 19200, B19200 },
{ 38400, B38400 }
#if defined(B57600)
, { 57600, B57600 }
#endif
#if defined(B115200)
, { 115200, B115200 }
#endif
#if defined(B230400)
, { 230400, B230400 }
#endif
};
static int convert_bitrate(int speed)
{
int i;
for (i = 0; i < sizeof(bitrate_conversion); i++)
if (bitrate_conversion[i][0] == speed)
return bitrate_conversion[i][1];
return -1;
}
int open_device(char *device, int speed)
{
int s = convert_bitrate(speed);
struct termios tc;
int fd = open(device, O_RDWR | O_SYNC | O_NOCTTY);
if (0 > fd) {
perror("open");
return -1;
}
if (0 > s) {
fprintf(stderr, "unknown bitrate %d\n", speed);
goto fail;
}
if (0 > tcgetattr(fd, &tc)) {
perror("tcgetattr");
goto fail;
}
cfmakeraw(&tc);
cfsetspeed(&tc, s);
if (tcsetattr(fd, TCSANOW, &tc)) {
perror("tcsetattr");
goto fail;
}
return fd;
fail:
close(fd);
return -1;
}
#define START_BYTE 0x7e
int recv_response(int fd, uint8_t *data, uint16_t *n)
{
uint8_t p = 0, checksum = 0;
uint16_t off = 0, frame_len;
for (;;) {
uint8_t b = 0;
int r = read(fd, &b, 1);
if (0 > r) {
perror("read");
return -1;
}
if (0 == r)
continue;
switch (p) {
case 0:
if (b == START_BYTE)
p++;
break;
case 1:
frame_len = ((uint16_t)b) << 8;
p++;
break;
case 2:
frame_len += b;
p++;
break;
default:
checksum += b;
if (p < frame_len+3) {
data[off++] = b;
p++;
break;
}
*n = off;
return (checksum == 0xff)? 0: -1;
}
}
}
static int send_byte(int fd, uint8_t b)
{
int n = write(fd, &b, 1);
return n;
}
static int send_frame(int fd, uint8_t api_id, uint8_t *frame, uint16_t frame_len)
{
static uint8_t frame_id = 1;
uint8_t checksum = api_id + frame_id;
int i;
send_byte(fd, START_BYTE);
send_byte(fd, (frame_len + 2) / 256);
send_byte(fd, (frame_len + 2) % 256);
send_byte(fd, api_id);
send_byte(fd, frame_id);
for (i = 0; i < frame_len; i++) {
uint8_t b = frame[i];
send_byte(fd, b);
checksum += b;
}
checksum = 0xff - checksum;
send_byte(fd, checksum);
if (++frame_id == 0) ++frame_id;
for (i = 0; i < frame_len; i++) {
uint8_t b = frame[i];
send_byte(fd, b);
checksum += b;
}
checksum = 0xff - checksum;
send_byte(fd, checksum);
if (++frame_id == 0) ++frame_id;
return 0; // FIXME
}
int send_remote_at_command_request(int fd, uint8_t *remote64, char *cmd, uint8_t *data, uint16_t n)
{
uint8_t frame[256];
frame[0] = remote64[0];
frame[1] = remote64[1];
frame[2] = remote64[2];
frame[3] = remote64[3];
frame[4] = remote64[4];
frame[5] = remote64[5];
frame[6] = remote64[6];
frame[7] = remote64[7];
frame[8] = 0xff;
frame[9] = 0xfe;
frame[10] = 0x02;
frame[11] = cmd[0];
frame[12] = cmd[1];
memcpy(frame + 13, data, n);
send_frame(fd, REMOTE_AT_REQUEST, frame, n + 13);
return 0;
}
int send_at_command_request(int fd, char *cmd, uint8_t *data, uint16_t n)
{
uint8_t frame[256];
frame[0] = cmd[0];
frame[1] = cmd[1];
memcpy(frame + 2, data, n);
send_frame(fd, AT_REQUEST, frame, n + 2);
return 0;
}
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