Browse Source
git-svn-id: https://arducopter.googlecode.com/svn/trunk@1504 f9c3cf11-9bcb-44bc-f272-b75c42450872master
deweibel@gmail.com
14 years ago
3 changed files with 271 additions and 0 deletions
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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
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/*
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GPS_MTK.cpp - Ublox GPS library for Arduino |
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Code by Jordi MuÒoz and Jose Julio. DIYDrones.com |
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This code works with boards based on ATMega168/328 and ATMega1280 (Serial port 1) |
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This library is free software; you can redistribute it and/or |
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modify it under the terms of the GNU Lesser General Public |
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License as published by the Free Software Foundation; either |
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version 2.1 of the License, or (at your option) any later version. |
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GPS configuration : Costum protocol |
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Baud rate : 38400 |
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Methods: |
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init() : GPS initialization |
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update() : Call this funcion as often as you want to ensure you read the incomming gps data |
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Properties: |
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lattitude : lattitude * 10000000 (long value) |
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longitude : longitude * 10000000 (long value) |
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altitude : altitude * 100 (meters) (long value) |
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ground_speed : Speed (m/s) * 100 (long value) |
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ground_course : Course (degrees) * 100 (long value) |
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new_data : 1 when a new data is received. |
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You need to write a 0 to new_data when you read the data |
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fix : 1: GPS NO fix, 2: 2D fix, 3: 3D fix. |
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*/ |
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#include "AP_GPS_IMU.h" |
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#include "WProgram.h" |
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// Constructors ////////////////////////////////////////////////////////////////
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AP_GPS_IMU::AP_GPS_IMU(Stream *s) : GPS(s) |
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{ |
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} |
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// Public Methods //////////////////////////////////////////////////////////////
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void
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AP_GPS_IMU::init(void) |
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{ |
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// we expect the stream to already be open at the corret bitrate
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} |
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// optimization : This code doesn't wait for data. It only proccess the data available.
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// We can call this function on the main loop (50Hz loop)
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// If we get a complete packet this function calls parse_IMU_gps() to parse and update the GPS info.
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bool
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AP_GPS_IMU::read(void) |
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{ |
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byte data; |
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int numc = 0; |
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static byte message_num = 0; |
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numc = _port->available(); |
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if (numc > 0){ |
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for (int i=0;i<numc;i++){ // Process bytes received
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data = _port->read(); |
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switch(step){ //Normally we start from zero. This is a state machine
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case 0:
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if(data == 0x44) // IMU sync char 1
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step++; //OH first data packet is correct, so jump to the next step
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break;
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case 1:
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if(data == 0x49) // IMU sync char 2
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step++; //ooh! The second data packet is correct, jump to the step 2
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else
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step=0; //Nop, is not correct so restart to step zero and try again.
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break; |
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case 2:
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if(data == 0x59) // IMU sync char 3
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step++; //ooh! The second data packet is correct, jump to the step 2
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else
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step=0; //Nop, is not correct so restart to step zero and try again.
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break; |
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case 3:
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if(data == 0x64) // IMU sync char 4
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step++; //ooh! The second data packet is correct, jump to the step 2
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else
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step=0; //Nop, is not correct so restart to step zero and try again.
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break; |
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case 4: |
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payload_length = data; |
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checksum(payload_length); |
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step++; |
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if (payload_length > 28){ |
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step = 0; //Bad data, so restart to step zero and try again.
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payload_counter = 0; |
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ck_a = 0; |
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ck_b = 0; |
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//payload_error_count++;
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}
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break; |
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case 5: |
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message_num = data; |
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checksum(data); |
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step++; |
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break; |
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case 6: // Payload data read...
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// We stay in this state until we reach the payload_length
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buffer[payload_counter] = data; |
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checksum(data); |
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payload_counter++; |
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if (payload_counter >= payload_length) {
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step++;
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} |
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break; |
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case 7: |
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GPS_ck_a = data; // First checksum byte
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step++; |
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break; |
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case 8: |
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GPS_ck_b = data; // Second checksum byte
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// We end the IMU/GPS read...
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// Verify the received checksum with the generated checksum..
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if((ck_a == GPS_ck_a) && (ck_b == GPS_ck_b)) { |
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if (message_num == 0x02) { |
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join_data(); |
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} else if (message_num == 0x03) { |
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GPS_join_data(); |
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} else if (message_num == 0x04) { |
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join_data_xplane(); |
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} else if (message_num == 0x0a) { |
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//PERF_join_data();
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} else { |
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// _error("Invalid message number = %d\n", (int)message_num);
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} |
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} else { |
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// _error("XXX Checksum error\n"); //bad checksum
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//imu_checksum_error_count++;
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}
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// Variable initialization
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step = 0; |
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payload_counter = 0; |
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ck_a = 0; |
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ck_b = 0; |
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break; |
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} |
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}// End for...
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} |
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} |
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/****************************************************************
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*
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****************************************************************/ |
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void AP_GPS_IMU::join_data(void) |
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{ |
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//Verifing if we are in class 1, you can change this "IF" for a "Switch" in case you want to use other IMU classes..
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//In this case all the message im using are in class 1, to know more about classes check PAGE 60 of DataSheet.
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//Storing IMU roll
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roll_sensor = *(int *)&buffer[0]; |
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//Storing IMU pitch
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pitch_sensor = *(int *)&buffer[2]; |
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//Storing IMU heading (yaw)
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ground_course = *(int *)&buffer[4]; |
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imu_ok = true; |
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} |
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void AP_GPS_IMU::join_data_xplane() |
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{ |
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//Storing IMU roll
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roll_sensor = *(int *)&buffer[0]; |
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//Storing IMU pitch
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pitch_sensor = *(int *)&buffer[2]; |
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//Storing IMU heading (yaw)
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ground_course = *(unsigned int *)&buffer[4]; |
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//Storing airspeed
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airspeed = *(int *)&buffer[6]; |
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imu_ok = true; |
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} |
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void AP_GPS_IMU::GPS_join_data(void) |
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{ |
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longitude = *(long *)&buffer[0]; // degrees * 10e7
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latitude = *(long *)&buffer[4]; |
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//Storing GPS Height above the sea level
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altitude = (long)*(int *)&buffer[8] * 10; |
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//Storing Speed
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speed_3d = ground_speed = (float)*(int *)&buffer[10]; |
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//We skip the gps ground course because we use yaw value from the IMU for ground course
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time = *(long *)&buffer[14]; |
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imu_health = buffer[15]; |
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new_data = true; |
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fix = true; |
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} |
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/****************************************************************
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*
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****************************************************************/ |
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// checksum algorithm
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void AP_GPS_IMU::checksum(byte data) |
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{ |
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ck_a += data; |
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ck_b += ck_a;
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} |
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@ -0,0 +1,44 @@
@@ -0,0 +1,44 @@
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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
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#ifndef AP_GPS_IMU_h |
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#define AP_GPS_IMU_h |
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#include <GPS.h> |
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#define MAXPAYLOAD 32 |
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class AP_GPS_IMU : public GPS { |
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public: |
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// Methods
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AP_GPS_IMU(Stream *s); |
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virtual void init(void); |
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virtual bool read(void); |
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// Properties
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long roll_sensor; // how much we're turning in deg * 100
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long pitch_sensor; // our angle of attack in deg * 100
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int airspeed; |
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float imu_health; |
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uint8_t imu_ok; |
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private: |
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// Packet checksums
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uint8_t ck_a;
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uint8_t ck_b; |
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uint8_t GPS_ck_a; |
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uint8_t GPS_ck_b; |
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uint8_t step; |
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uint8_t msg_class; |
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uint8_t message_num; |
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uint8_t payload_length; |
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uint8_t payload_counter; |
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uint8_t buffer[MAXPAYLOAD]; |
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void join_data(); |
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void join_data_xplane(); |
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void GPS_join_data(); |
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void checksum(unsigned char data); |
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}; |
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#endif |
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