hott_sensors.cpp

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/****************************************************************************
 *
 *   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
 *   Author: Simon Wilks <sjwilks@gmail.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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/**
 * @file hott_sensors.c
 * @author Simon Wilks <sjwilks@gmail.com>
 *
 * Graupner HoTT sensor driver implementation.
 *
 * Poll any sensors connected to the PX4 via the telemetry wire.
 */

#include <fcntl.h>
#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/defines.h>
#include <px4_platform_common/tasks.h>
#include <poll.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <systemlib/err.h>

#include "../comms.h"
#include "../messages.h"

#define DEFAULT_UART "/dev/ttyS0";      /**< USART1 */

static int thread_should_exit = false;      /**< Deamon exit flag */
static int thread_running = false;      /**< Deamon status flag */
static int deamon_task;             /**< Handle of deamon task / thread */
static const char daemon_name[] = "hott_sensors";
static const char commandline_usage[] = "usage: hott_sensors start|status|stop [-d <device>]";

/**
 * Deamon management function.
 */
extern "C" __EXPORT int hott_sensors_main(int argc, char *argv[]);

/**
 * Mainloop of daemon.
 */
int hott_sensors_thread_main(int argc, char *argv[]);

static int recv_data(int uart, uint8_t *buffer, size_t *size, uint8_t *id);
static int send_poll(int uart, uint8_t *buffer, size_t size);

int
send_poll(int uart, uint8_t *buffer, size_t size)
{
    for (size_t i = 0; i < size; i++) {
        write(uart, &buffer[i], sizeof(buffer[i]));

        /* Sleep before sending the next byte. */
        usleep(POST_WRITE_DELAY_IN_USECS);
    }

    /* A hack the reads out what was written so the next read from the receiver doesn't get it. */
    /* TODO: Fix this!! */
    uint8_t dummy[size];
    read(uart, &dummy, size);

    return OK;
}

int
recv_data(int uart, uint8_t *buffer, size_t *size, uint8_t *id)
{
    static const int timeout_ms = 1000;

    struct pollfd fds;
    fds.fd = uart;
    fds.events = POLLIN;

    // XXX should this poll be inside the while loop???
    if (poll(&fds, 1, timeout_ms) > 0) {
        int i = 0;
        bool stop_byte_read = false;

        while (true)  {
            read(uart, &buffer[i], sizeof(buffer[i]));

            if (stop_byte_read) {
                // XXX process checksum
                *size = ++i;
                return OK;
            }

            // XXX can some other field not have the STOP BYTE value?
            if (buffer[i] == STOP_BYTE) {
                *id = buffer[1];
                stop_byte_read = true;
            }

            i++;
        }
    }

    return PX4_ERROR;
}

int
hott_sensors_thread_main(int argc, char *argv[])
{
    warnx("starting");

    thread_running = true;

    const char *device = DEFAULT_UART;

    /* read commandline arguments */
    for (int i = 0; i < argc && argv[i]; i++) {
        if (strcmp(argv[i], "-d") == 0 || strcmp(argv[i], "--device") == 0) { //device set
            if (argc > i + 1) {
                device = argv[i + 1];

            } else {
                thread_running = false;
                errx(1, "missing parameter to -d\n%s", commandline_usage);
            }
        }
    }

    /* enable UART, writes potentially an empty buffer, but multiplexing is disabled */
    const int uart = open_uart(device);

    if (uart < 0) {
        errx(1, "Open fail, exiting.");
        thread_running = false;
    }

    init_pub_messages();

    uint8_t buffer[MAX_MESSAGE_BUFFER_SIZE];
    size_t size = 0;
    uint8_t id = 0;

    while (!thread_should_exit) {
        // Currently we only support a General Air Module sensor.
        build_gam_request(&buffer[0], &size);
        send_poll(uart, buffer, size);

        // The sensor will need a little time before it starts sending.
        usleep(5000);

        recv_data(uart, &buffer[0], &size, &id);

        // Determine which module sent it and process accordingly.
        if (id == GAM_SENSOR_ID) {
            publish_gam_message(buffer);

        } else {
            warnx("Unknown sensor ID: %d", id);
        }
    }

    warnx("exiting");
    close(uart);
    thread_running = false;

    return 0;
}

/**
 * Process command line arguments and start the daemon.
 */
int
hott_sensors_main(int argc, char *argv[])
{
    if (argc < 2) {
        errx(1, "missing command\n%s", commandline_usage);
    }

    if (!strcmp(argv[1], "start")) {

        if (thread_running) {
            warnx("already running");
            exit(0);
        }

        thread_should_exit = false;
        deamon_task = px4_task_spawn_cmd(daemon_name,
                         SCHED_DEFAULT,
                         SCHED_PRIORITY_DEFAULT,
                         1024,
                         hott_sensors_thread_main,
                         (argv) ? (char *const *)&argv[2] : (char *const *)NULL);
        exit(0);
    }

    if (!strcmp(argv[1], "stop")) {
        thread_should_exit = true;
        exit(0);
    }

    if (!strcmp(argv[1], "status")) {
        if (thread_running) {
            warnx("is running");

        } else {
            warnx("not started");
        }

        exit(0);
    }

    errx(1, "unrecognized command\n%s", commandline_usage);
}