mirror of https://github.com/ArduPilot/ardupilot
154 lines
3.8 KiB
C++
154 lines
3.8 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
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//
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// DIYDrones Custom Mediatek GPS driver for ArduPilot and ArduPilotMega.
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// Code by Michael Smith, Jordi Munoz and Jose Julio, DIYDrones.com
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//
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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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//
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// GPS configuration : Custom protocol per "DIYDrones Custom Binary Sentence Specification V1.1"
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//
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#include "GCS_SIMPLE.h"
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#include <stdint.h>
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// Public Methods //////////////////////////////////////////////////////////////
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GCS_SIMPLE::GCS_SIMPLE(Stream *s) : _port(s)
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{
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}
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// Process bytes available from the stream
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//
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// The stream is assumed to contain only our custom message. If it
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// contains other messages, and those messages contain the preamble bytes,
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// it is possible for this code to become de-synchronised. Without
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// buffering the entire message and re-processing it from the top,
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// this is unavoidable.
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//
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// The lack of a standard header length field makes it impossible to skip
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// unrecognised messages.
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//
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void
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GCS_SIMPLE::ack(void)
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{
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buff_pointer = 0;
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flush(1);
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}
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bool
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GCS_SIMPLE::read(void)
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{
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uint8_t data;
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int numc;
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bool parsed = false;
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numc = _port->available();
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for (int i = 0; i < numc; i++){
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// Process bytes received
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// read the next byte
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data = _port->read();
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//_port->write(data);
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restart:
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switch(_step){
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case 0:
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if(52 == data){
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_step++;
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_payload_counter = 0;
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}
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break;
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case 1:
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if (68 == data) {
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_step++;
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break;
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}
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_step = 0;
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goto restart;
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case 2:
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_length = data;
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_step++;
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break;
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case 3:
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_id = data;
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_step++;
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break;
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case 4:
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_buffer.bytes[_payload_counter++] = data;
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if (_payload_counter == sizeof(_buffer)){
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_step = 0;
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parsed = true;
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}
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index = _buffer.msg.index;
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id = _buffer.msg.id;
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p1 = _buffer.msg.p1;
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altitude = _buffer.msg.altitude;
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latitude = _buffer.msg.latitude;
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longitude = _buffer.msg.longitude;
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break;
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}
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}
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return parsed;
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}
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// Add binary values to the buffer
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void
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GCS_SIMPLE::write_byte(uint8_t val)
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{
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mess_buffer[buff_pointer++] = val;
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}
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void
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GCS_SIMPLE::write_int(int val )
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{
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int_out.value = val;
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mess_buffer[buff_pointer++] = int_out.bytes[0];
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mess_buffer[buff_pointer++] = int_out.bytes[1];
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}
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void
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GCS_SIMPLE::write_float(float val)
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{
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double_out.float_value = val;
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mess_buffer[buff_pointer++] = double_out.bytes[0];
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mess_buffer[buff_pointer++] = double_out.bytes[1];
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mess_buffer[buff_pointer++] = double_out.bytes[2];
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mess_buffer[buff_pointer++] = double_out.bytes[3];
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}
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void
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GCS_SIMPLE::write_long(long val)
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{
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double_out.long_value = val;
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mess_buffer[buff_pointer++] = double_out.bytes[0];
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mess_buffer[buff_pointer++] = double_out.bytes[1];
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mess_buffer[buff_pointer++] = double_out.bytes[2];
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mess_buffer[buff_pointer++] = double_out.bytes[3];
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}
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void
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GCS_SIMPLE::flush(uint8_t msg_id)
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{
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_port->print("4D"); // This is the message preamble
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_port->write(buff_pointer); // Length
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_port->write(msg_id); // id
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for (uint8_t i = 0; i < buff_pointer; i++) {
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_port->write(mess_buffer[i]);
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}
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buff_pointer = 0;
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}
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