Refactor the EM-406 support into a 406-specific init routine and a generic SiRF parser.

git-svn-id: https://arducopter.googlecode.com/svn/trunk@423 f9c3cf11-9bcb-44bc-f272-b75c42450872
This commit is contained in:
DrZiplok@gmail.com 2010-09-07 04:20:34 +00:00
parent c981b7d0b0
commit c6ceb85c21
4 changed files with 322 additions and 158 deletions

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@ -1,156 +1,38 @@
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
/*
GPS_406.cpp - 406 GPS library for Arduino
Code by Jason Short, Jordi Muñoz and Jose Julio. DIYDrones.com
This code works with boards based on ATMega168/328 ATMega1280 (Serial port 1)
This library is free software; you can redistribute it and / or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
GPS configuration : 406 protocol
Baud rate : 57600
Methods:
init() : GPS initialization
update() : Call this funcion as often as you want to ensure you read the incomming gps data
Properties:
Latitude : Latitude * 10,000,000 (long value)
Longitude : Longitude * 10,000,000 (long value)
altitude : altitude * 100 (meters) (long value)
ground_speed : Speed (m/s) * 100 (long value)
ground_course : Course (degrees) * 100 (long value)
new_data : 1 when a new data is received.
You need to write a 0 to new_data when you read the data
fix : 1: GPS FIX, 0: No fix (normal logic)
*/
//
// GPS_406.cpp - 406 GPS library for Arduino
// Code by Michael Smith, Jason Short, Jordi Muñoz and Jose Julio. DIYDrones.com
// This code works with boards based on ATMega168/328 ATMega1280 (Serial port 1)
//
// This library is free software; you can redistribute it and / or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
#include "../FastSerial/FastSerial.h" // because we need to change baud rates... ugh.
#include "AP_GPS_406.h"
#include "WProgram.h"
#include <Stream.h>
uint8_t AP_GPS_406::buffer[MAXPAYLOAD] = {0x24,0x50,0x53,0x52,0x46,0x31,0x30,0x30,0x2C,0x30,0x2C,0x35,0x37,0x36,0x30,0x30,0x2C,0x38,0x2C,0x31,0x2C,0x30,0x2A,0x33,0x37,0x0D,0x0A};
#define PAYLOAD_LENGTH 92
#define BAUD_RATE 57600
static const char init_str[] = "$PSRF100,0,57600,8,1,0*37";
// Constructors ////////////////////////////////////////////////////////////////
AP_GPS_406::AP_GPS_406(Stream *s) : GPS(s)
AP_GPS_406::AP_GPS_406(Stream *s) : AP_GPS_SIRF(s)
{
}
// Public Methods ////////////////////////////////////////////////////////////////////
void AP_GPS_406::init(void)
{
change_to_sirf_protocol(); // Changes to SIRF protocol and sets baud rate
delay(100); // Waits fot the GPS to start_UP
configure_gps(); // Function to configure GPS, to output only the desired msg's
}
_change_to_sirf_protocol(); // Changes to SIRF protocol and sets baud rate
_configure_gps(); // Function to configure GPS, to output only the desired msg's
// optimization : This code doesn´t wait for data, only proccess the data available
// We can call this function on the main loop (50Hz loop)
// If we get a complete packet this function calls parse_gps() to parse and update the GPS info.
void AP_GPS_406::update(void)
{
byte data;
int numc;
numc = _port->available();
if (numc > 0){
for (int i = 0; i < numc; i++){ // Process bytes received
data = _port->read();
switch(step){
case 0:
if(data == 0xA0)
step++;
break;
case 1:
if(data == 0xA2)
step++;
else
step = 0;
break;
/* case 2:
if(data == 0xA2)
step++;
else
step = 0;
break;
*/
case 2:
if(data == 0x00)
step++;
else
step = 0;
break;
case 3:
if(data == 0x5B)
step++;
else
step = 0;
break;
case 4:
if(data == 0x29){
payload_counter = 0;
step++;
}else
step = 0;
break;
case 5: // Payload data read...
if (payload_counter <= PAYLOAD_LENGTH){ // We stay in this state until we reach the payload_length
buffer[payload_counter] = data;
payload_counter++;
if (payload_counter == PAYLOAD_LENGTH){
parse_gps();
step = 0;
}
}
break;
}
} // End for...
}
AP_GPS_SIRF::init(); // let the superclass do anything it might need here
}
// Private Methods //////////////////////////////////////////////////////////////
void
AP_GPS_406::parse_gps(void)
{
uint8_t j;
fix = buffer[1] > 0;
latitude = _swapl(&buffer[22]); // lat * 10, 000, 000
longitude = _swapl(&buffer[26]); // lon * 10, 000, 000
altitude = _swapl(&buffer[34]); // alt in meters * 100
ground_speed = _swapi(&buffer[39]); // meters / second * 100
if (ground_speed >= 50) { // Only updates data if we are really moving...
ground_course = (unsigned int)_swapi(&buffer[41]); // meters / second * 100
}
//climb_rate = _swapi(&buffer[45]); // meters / second * 100
if (latitude == 0) {
new_data = false;
fix = false;
} else {
new_data = true;
}
}
void
AP_GPS_406::configure_gps(void)
AP_GPS_406::_configure_gps(void)
{
const uint8_t gps_header[] = {0xA0, 0xA2, 0x00, 0x08, 0xA6, 0x00};
const uint8_t gps_payload[] = {0x02, 0x04, 0x07, 0x09, 0x1B};
@ -170,23 +52,22 @@ AP_GPS_406::configure_gps(void)
}
}
// The EM406 defalts to NMEA at 4800bps. We want to switch it to SiRF binary
// mode at a higher rate.
//
// The change is sticky, but only for as long as the internal supercap holds
// settings (usually less than a week).
//
void
AP_GPS_406::change_to_sirf_protocol(void)
AP_GPS_406::_change_to_sirf_protocol(void)
{
FastSerial *fs = (FastSerial *)_port; // this is a bit grody...
fs->begin(4800); // First try at 4800bps
fs->begin(4800);
delay(300);
_port->write(buffer, 28); // Sending special bytes declared at the beginning
_port->print(init_str);
delay(300);
fs->begin(9600); // Then try at 9600bps
delay(300);
_port->write(buffer, 28);
delay(300);
fs->begin(BAUD_RATE); // Finally try at the configured bit rate (57600?)
delay(300);
_port->write(buffer, 28);
fs->begin(GPS_406_BITRATE);
}

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@ -1,28 +1,31 @@
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
//
// EM406 GPS driver for ArduPilot and ArduPilotMega.
// Code by Michael Smith, Jason Short, Jordi Muñoz and Jose Julio. DIYDrones.com
//
// This library is free software; you can redistribute it and / or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
#ifndef AP_GPS_406_h
#define AP_GPS_406_h
#include <GPS.h>
#define MAXPAYLOAD 100
#include "AP_GPS_SIRF.h"
class AP_GPS_406 : public GPS
#define GPS_406_BITRATE 57600
class AP_GPS_406 : public AP_GPS_SIRF
{
public:
// Methods
AP_GPS_406(Stream *port);
void init();
void update();
void init();
private:
// Internal variables
uint8_t step;
uint8_t payload_counter;
static uint8_t buffer[MAXPAYLOAD];
void parse_gps();
void change_to_sirf_protocol(void);
void configure_gps(void);
void _change_to_sirf_protocol(void);
void _configure_gps(void);
};
#endif

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
//
// SiRF Binary GPS driver for ArduPilot and ArduPilotMega.
// Code by Michael Smith.
//
// This library is free software; you can redistribute it and / or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
#include "AP_GPS_SIRF.h"
#include "WProgram.h"
// Initialisation messages
//
// Turn off all messages except for 0x29.
//
// XXX the bytes show up on the wire, but at least my test unit (EM-411) seems to ignore them.
//
static uint8_t init_messages[] = {
0xa0, 0xa2, 0x00, 0x08, 0xa6, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xa8, 0xb0, 0xb3,
0xa0, 0xa2, 0x00, 0x08, 0xa6, 0x00, 0x29, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0xd0, 0xb0, 0xb3
};
// Constructors ////////////////////////////////////////////////////////////////
AP_GPS_SIRF::AP_GPS_SIRF(Stream *s) : GPS(s)
{
}
// Public Methods //////////////////////////////////////////////////////////////
void AP_GPS_SIRF::init(void)
{
// For modules that default to something other than SiRF binary,
// the module-specific subclass should take care of switching to binary mode.
_port->write(init_messages, sizeof(init_messages));
}
// Process bytes available from the stream
//
// The stream is assumed to contain only messages we recognise. If it
// contains other messages, and those messages contain the preamble
// bytes, it is possible for this code to fail to synchronise to the
// stream immediately. Without buffering the entire message and
// re-processing it from the top, this is unavoidable. The parser
// attempts to avoid this when possible.
//
void AP_GPS_SIRF::update(void)
{
byte data;
int numc;
numc = _port->available();
while(numc--) {
// read the next byte
data = _port->read();
switch(_step){
// Message preamble detection
//
// If we fail to match any of the expected bytes, we reset
// the state machine and re-consider the failed byte as
// the first byte of the preamble. This improves our
// chances of recovering from a mismatch and makes it less
// likely that we will be fooled by the preamble appearing
// as data in some other message.
//
case 1:
if (PREAMBLE2 == data) {
_step++;
break;
}
_step = 0;
// FALLTHROUGH
case 0:
if(PREAMBLE1 == data)
_step++;
break;
// Message length
//
// We always collect the length so that we can avoid being
// fooled by preamble bytes in messages.
//
case 2:
_step++;
_payload_length = (uint16_t)data << 8;
break;
case 3:
_step++;
_payload_length |= data;
_payload_counter = 0;
_checksum = 0;
break;
// Message header processing
//
// We sniff the message ID to determine whether we are going
// to gather the message bytes or just discard them.
//
case 4:
_step++;
_accumulate(data);
_payload_length--;
_gather = false;
switch(data) {
case MSG_GEONAV:
if (_payload_length == sizeof(sirf_geonav)) {
_gather = true;
_msg_id = data;
}
break;
default:
_error("ignoring message %d\n", (int)data);
}
break;
// Receive message data
//
// Note that we are effectively guaranteed by the protocol
// that the checksum and postamble cannot be mistaken for
// the preamble, so if we are discarding bytes in this
// message when the payload is done we return directly
// to the preamble detector rather than bothering with
// the checksum logic.
//
case 5:
if (_gather) { // gather data if requested
_accumulate(data);
_buffer.bytes[_payload_counter] = data;
if (++_payload_counter == _payload_length)
_step++;
} else {
if (++_payload_counter == _payload_length)
_step = 0;
}
break;
// Checksum and message processing
//
case 6:
_step++;
if ((_checksum >> 8) != data) {
_error("GPS_SIRF: checksum error\n");
_step = 0;
}
break;
case 7:
_step = 0;
if ((_checksum & 0xff) != data) {
_error("GPS_SIRF: checksum error\n");
break;
}
if (_gather) {
_parse_gps(); // Parse the new GPS packet
}
}
}
}
void
AP_GPS_SIRF::_parse_gps(void)
{
switch(_msg_id) {
case MSG_GEONAV:
time = _swapl(&_buffer.nav.time);
fix = (0 == _buffer.nav.fix_invalid) && (FIX_3D == (_buffer.nav.fix_type & FIX_MASK));
latitude = _swapl(&_buffer.nav.latitude);
longitude = _swapl(&_buffer.nav.longitude);
altitude = _swapl(&_buffer.nav.altitude_msl);
ground_speed = _swapi(&_buffer.nav.ground_speed);
ground_course = _swapi(&_buffer.nav.ground_course);
num_sats = _buffer.nav.satellites;
break;
}
new_data = true;
}
void
AP_GPS_SIRF::_accumulate(uint8_t val)
{
_checksum = (_checksum + val) & 0x7fff;
}

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
//
// SiRF Binary GPS driver for ArduPilot and ArduPilotMega.
// Code by Michael Smith.
//
// This library is free software; you can redistribute it and / or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
#ifndef AP_GPS_SIRF_h
#define AP_GPS_SIRF_h
#include <GPS.h>
class AP_GPS_SIRF : public GPS {
public:
AP_GPS_SIRF(Stream *s);
virtual void init();
virtual void update();
private:
#pragma pack(1)
struct sirf_geonav {
uint16_t fix_invalid;
uint16_t fix_type;
uint16_t week;
uint32_t time;
uint16_t year;
uint8_t month;
uint8_t day;
uint8_t hour;
uint8_t minute;
uint16_t second;
uint32_t satellites_used;
int32_t latitude;
int32_t longitude;
int32_t altitude_ellipsoid;
int32_t altitude_msl;
int8_t map_datum;
int16_t ground_speed;
int16_t ground_course;
int16_t res1;
int16_t climb_rate;
uint16_t heading_rate;
uint32_t horizontal_position_error;
uint32_t vertical_position_error;
uint32_t time_error;
int16_t horizontal_velocity_error;
int32_t clock_bias;
uint32_t clock_bias_error;
int32_t clock_drift;
uint32_t clock_drift_error;
uint32_t distance;
uint16_t distance_error;
uint16_t heading_error;
uint8_t satellites;
uint8_t hdop;
uint8_t mode_info;
};
#pragma pack(pop)
enum sirf_protocol_bytes {
PREAMBLE1 = 0xa0,
PREAMBLE2 = 0xa2,
POSTAMBLE1 = 0xb0,
POSTAMBLE2 = 0xb3,
MSG_GEONAV = 0x29
};
enum sirf_fix_type {
FIX_3D = 0x6,
FIX_MASK = 0x7
};
// State machine state
uint8_t _step;
uint16_t _checksum;
bool _gather;
uint16_t _payload_length;
uint16_t _payload_counter;
uint8_t _msg_id;
// Message buffer
union {
sirf_geonav nav;
uint8_t bytes[];
} _buffer;
void _parse_gps(void);
void _accumulate(uint8_t val);
};
#endif // AP_GPS_SIRF_h