diff options
Diffstat (limited to 'apps/drivers/gps/mtk.cpp')
| -rw-r--r-- | apps/drivers/gps/mtk.cpp | 274 |
1 files changed, 274 insertions, 0 deletions
diff --git a/apps/drivers/gps/mtk.cpp b/apps/drivers/gps/mtk.cpp new file mode 100644 index 000000000..4762bd503 --- /dev/null +++ b/apps/drivers/gps/mtk.cpp @@ -0,0 +1,274 @@ +/**************************************************************************** + * + * Copyright (C) 2013 PX4 Development Team. All rights reserved. + * Author: Thomas Gubler <thomasgubler@student.ethz.ch> + * Julian Oes <joes@student.ethz.ch> + * + * 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 + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/* @file mkt.cpp */ + +#include <unistd.h> +#include <stdio.h> +#include <poll.h> +#include <math.h> +#include <string.h> +#include <assert.h> +#include <systemlib/err.h> +#include <drivers/drv_hrt.h> + +#include "mtk.h" + + +MTK::MTK(const int &fd, struct vehicle_gps_position_s *gps_position) : +_fd(fd), +_gps_position(gps_position), +_mtk_revision(0) +{ + decode_init(); +} + +MTK::~MTK() +{ +} + +int +MTK::configure(unsigned &baudrate) +{ + /* set baudrate first */ + if (GPS_Helper::set_baudrate(_fd, MTK_BAUDRATE) != 0) + return -1; + + baudrate = MTK_BAUDRATE; + + /* Write config messages, don't wait for an answer */ + if (strlen(MTK_OUTPUT_5HZ) != write(_fd, MTK_OUTPUT_5HZ, strlen(MTK_OUTPUT_5HZ))) { + warnx("mtk: config write failed"); + return -1; + } + usleep(10000); + + if (strlen(MTK_SET_BINARY) != write(_fd, MTK_SET_BINARY, strlen(MTK_SET_BINARY))) { + warnx("mtk: config write failed"); + return -1; + } + usleep(10000); + + if (strlen(SBAS_ON) != write(_fd, SBAS_ON, strlen(SBAS_ON))) { + warnx("mtk: config write failed"); + return -1; + } + usleep(10000); + + if (strlen(WAAS_ON) != write(_fd, WAAS_ON, strlen(WAAS_ON))) { + warnx("mtk: config write failed"); + return -1; + } + usleep(10000); + + if (strlen(MTK_NAVTHRES_OFF) != write(_fd, MTK_NAVTHRES_OFF, strlen(MTK_NAVTHRES_OFF))) { + warnx("mtk: config write failed"); + return -1; + } + + return 0; +} + +int +MTK::receive(unsigned timeout) +{ + /* poll descriptor */ + pollfd fds[1]; + fds[0].fd = _fd; + fds[0].events = POLLIN; + + uint8_t buf[32]; + gps_mtk_packet_t packet; + + /* timeout additional to poll */ + uint64_t time_started = hrt_absolute_time(); + + int j = 0; + ssize_t count = 0; + + while (true) { + + /* first read whatever is left */ + if (j < count) { + /* pass received bytes to the packet decoder */ + while (j < count) { + if (parse_char(buf[j], packet) > 0) { + handle_message(packet); + return 1; + } + /* in case we keep trying but only get crap from GPS */ + if (time_started + timeout*1000 < hrt_absolute_time() ) { + return -1; + } + j++; + } + /* everything is read */ + j = count = 0; + } + + /* then poll for new data */ + int ret = ::poll(fds, sizeof(fds) / sizeof(fds[0]), timeout); + + if (ret < 0) { + /* something went wrong when polling */ + return -1; + + } else if (ret == 0) { + /* Timeout */ + return -1; + + } else if (ret > 0) { + /* if we have new data from GPS, go handle it */ + if (fds[0].revents & POLLIN) { + /* + * We are here because poll says there is some data, so this + * won't block even on a blocking device. If more bytes are + * available, we'll go back to poll() again... + */ + count = ::read(_fd, buf, sizeof(buf)); + } + } + } +} + +void +MTK::decode_init(void) +{ + _rx_ck_a = 0; + _rx_ck_b = 0; + _rx_count = 0; + _decode_state = MTK_DECODE_UNINIT; +} +int +MTK::parse_char(uint8_t b, gps_mtk_packet_t &packet) +{ + int ret = 0; + + if (_decode_state == MTK_DECODE_UNINIT) { + + if (b == MTK_SYNC1_V16) { + _decode_state = MTK_DECODE_GOT_CK_A; + _mtk_revision = 16; + } else if (b == MTK_SYNC1_V19) { + _decode_state = MTK_DECODE_GOT_CK_A; + _mtk_revision = 19; + } + + } else if (_decode_state == MTK_DECODE_GOT_CK_A) { + if (b == MTK_SYNC2) { + _decode_state = MTK_DECODE_GOT_CK_B; + + } else { + // Second start symbol was wrong, reset state machine + decode_init(); + } + + } else if (_decode_state == MTK_DECODE_GOT_CK_B) { + // Add to checksum + if (_rx_count < 33) + add_byte_to_checksum(b); + + // Fill packet buffer + ((uint8_t*)(&packet))[_rx_count] = b; + _rx_count++; + + /* Packet size minus checksum, XXX ? */ + if (_rx_count >= sizeof(packet)) { + /* Compare checksum */ + if (_rx_ck_a == packet.ck_a && _rx_ck_b == packet.ck_b) { + ret = 1; + } else { + warnx("MTK Checksum invalid"); + ret = -1; + } + // Reset state machine to decode next packet + decode_init(); + } + } + return ret; +} + +void +MTK::handle_message(gps_mtk_packet_t &packet) +{ + if (_mtk_revision == 16) { + _gps_position->lat = packet.latitude * 10; // from degrees*1e6 to degrees*1e7 + _gps_position->lon = packet.longitude * 10; // from degrees*1e6 to degrees*1e7 + } else if (_mtk_revision == 19) { + _gps_position->lat = packet.latitude; // both degrees*1e7 + _gps_position->lon = packet.longitude; // both degrees*1e7 + } else { + warnx("mtk: unknown revision"); + _gps_position->lat = 0; + _gps_position->lon = 0; + } + _gps_position->alt = (int32_t)(packet.msl_altitude * 10); // from cm to mm + _gps_position->fix_type = packet.fix_type; + _gps_position->eph_m = packet.hdop; // XXX: Check this because eph_m is in m and hdop is without unit + _gps_position->epv_m = 0.0; //unknown in mtk custom mode + _gps_position->vel_m_s = ((float)packet.ground_speed)*1e-2f; // from cm/s to m/s + _gps_position->cog_rad = ((float)packet.heading) * M_DEG_TO_RAD_F * 1e-2f; //from deg *100 to rad + _gps_position->satellites_visible = packet.satellites; + + /* convert time and date information to unix timestamp */ + struct tm timeinfo; //TODO: test this conversion + uint32_t timeinfo_conversion_temp; + + timeinfo.tm_mday = packet.date * 1e-4; + timeinfo_conversion_temp = packet.date - timeinfo.tm_mday * 1e4; + timeinfo.tm_mon = timeinfo_conversion_temp * 1e-2 - 1; + timeinfo.tm_year = (timeinfo_conversion_temp - (timeinfo.tm_mon + 1) * 1e2) + 100; + + timeinfo.tm_hour = packet.utc_time * 1e-7; + timeinfo_conversion_temp = packet.utc_time - timeinfo.tm_hour * 1e7; + timeinfo.tm_min = timeinfo_conversion_temp * 1e-5; + timeinfo_conversion_temp -= timeinfo.tm_min * 1e5; + timeinfo.tm_sec = timeinfo_conversion_temp * 1e-3; + timeinfo_conversion_temp -= timeinfo.tm_sec * 1e3; + time_t epoch = mktime(&timeinfo); + + _gps_position->time_gps_usec = epoch * 1e6; //TODO: test this + _gps_position->time_gps_usec += timeinfo_conversion_temp * 1e3; + _gps_position->timestamp_position = _gps_position->timestamp_time = hrt_absolute_time(); + + return; +} + +void +MTK::add_byte_to_checksum(uint8_t b) +{ + _rx_ck_a = _rx_ck_a + b; + _rx_ck_b = _rx_ck_b + _rx_ck_a; +} |