mirror of https://github.com/ArduPilot/ardupilot
344 lines
9.9 KiB
C++
344 lines
9.9 KiB
C++
/*
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st24 decoder, based on PX4Firmware/src/rc/lib/rc/st24.c from PX4Firmware
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modified for use in AP_HAL_* by Andrew Tridgell
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*/
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/****************************************************************************
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*
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* Copyright (c) 2014 PX4 Development Team. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/*
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* @file st24.cpp
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*
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* RC protocol implementation for Yuneec ST24 transmitter.
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*
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* @author Lorenz Meier <lm@inf.ethz.ch>
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include "st24.h"
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#define ST24_DATA_LEN_MAX 64
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#define ST24_STX1 0x55
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#define ST24_STX2 0x55
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enum ST24_PACKET_TYPE {
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ST24_PACKET_TYPE_CHANNELDATA12 = 0,
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ST24_PACKET_TYPE_CHANNELDATA24,
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ST24_PACKET_TYPE_TRANSMITTERGPSDATA
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};
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#pragma pack(push, 1)
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typedef struct {
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uint8_t header1; ///< 0x55 for a valid packet
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uint8_t header2; ///< 0x55 for a valid packet
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uint8_t length; ///< length includes type, data, and crc = sizeof(type)+sizeof(data[payload_len])+sizeof(crc8)
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uint8_t type; ///< from enum ST24_PACKET_TYPE
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uint8_t st24_data[ST24_DATA_LEN_MAX];
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uint8_t crc8; ///< crc8 checksum, calculated by st24_common_crc8 and including fields length, type and st24_data
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} ReceiverFcPacket;
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/**
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* RC Channel data (12 channels).
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*
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* This is incoming from the ST24
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*/
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typedef struct {
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uint16_t t; ///< packet counter or clock
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uint8_t rssi; ///< signal strength
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uint8_t packet_count; ///< Number of UART packets sent since reception of last RF frame (this tells something about age / rate)
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uint8_t channel[18]; ///< channel data, 12 channels (12 bit numbers)
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} ChannelData12;
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/**
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* RC Channel data (12 channels).
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*
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*/
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typedef struct {
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uint16_t t; ///< packet counter or clock
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uint8_t rssi; ///< signal strength
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uint8_t packet_count; ///< Number of UART packets sent since reception of last RF frame (this tells something about age / rate)
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uint8_t channel[36]; ///< channel data, 24 channels (12 bit numbers)
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} ChannelData24;
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/**
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* Telemetry packet
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*
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* This is outgoing to the ST24
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*
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* imuStatus:
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* 8 bit total
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* bits 0-2 for status
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* - value 0 is FAILED
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* - value 1 is INITIALIZING
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* - value 2 is RUNNING
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* - values 3 through 7 are reserved
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* bits 3-7 are status for sensors (0 or 1)
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* - mpu6050
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* - accelerometer
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* - primary gyro x
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* - primary gyro y
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* - primary gyro z
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*
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* pressCompassStatus
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* 8 bit total
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* bits 0-3 for compass status
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* - value 0 is FAILED
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* - value 1 is INITIALIZING
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* - value 2 is RUNNING
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* - value 3 - 15 are reserved
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* bits 4-7 for pressure status
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* - value 0 is FAILED
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* - value 1 is INITIALIZING
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* - value 2 is RUNNING
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* - value 3 - 15 are reserved
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*
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*/
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typedef struct {
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uint16_t t; ///< packet counter or clock
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int32_t lat; ///< latitude (degrees) +/- 90 deg
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int32_t lon; ///< longitude (degrees) +/- 180 deg
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int32_t alt; ///< 0.01m resolution, altitude (meters)
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int16_t vx, vy, vz; ///< velocity 0.01m res, +/-320.00 North-East- Down
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uint8_t nsat; ///<number of satellites
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uint8_t voltage; ///< 25.4V voltage = 5 + 255*0.1 = 30.5V, min=5V
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uint8_t current; ///< 0.5A resolution
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int16_t roll, pitch, yaw; ///< 0.01 degree resolution
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uint8_t motorStatus; ///< 1 bit per motor for status 1=good, 0= fail
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uint8_t imuStatus; ///< inertial measurement unit status
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uint8_t pressCompassStatus; ///< baro / compass status
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} TelemetryData;
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#pragma pack(pop)
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enum ST24_DECODE_STATE {
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ST24_DECODE_STATE_UNSYNCED = 0,
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ST24_DECODE_STATE_GOT_STX1,
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ST24_DECODE_STATE_GOT_STX2,
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ST24_DECODE_STATE_GOT_LEN,
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ST24_DECODE_STATE_GOT_TYPE,
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ST24_DECODE_STATE_GOT_DATA
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};
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/* define range mapping here, -+100% -> 1000..2000 */
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#define ST24_RANGE_MIN 0.0f
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#define ST24_RANGE_MAX 4096.0f
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#define ST24_TARGET_MIN 1000.0f
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#define ST24_TARGET_MAX 2000.0f
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/* pre-calculate the floating point stuff as far as possible at compile time */
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#define ST24_SCALE_FACTOR ((ST24_TARGET_MAX - ST24_TARGET_MIN) / (ST24_RANGE_MAX - ST24_RANGE_MIN))
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#define ST24_SCALE_OFFSET (int)(ST24_TARGET_MIN - (ST24_SCALE_FACTOR * ST24_RANGE_MIN + 0.5f))
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static enum ST24_DECODE_STATE _decode_state = ST24_DECODE_STATE_UNSYNCED;
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static uint8_t _rxlen;
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static ReceiverFcPacket _rxpacket;
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static uint8_t st24_common_crc8(uint8_t *ptr, uint8_t len)
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{
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uint8_t i, crc ;
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crc = 0;
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while (len--) {
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for (i = 0x80; i != 0; i >>= 1) {
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if ((crc & 0x80) != 0) {
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crc <<= 1;
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crc ^= 0x07;
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} else {
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crc <<= 1;
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}
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if ((*ptr & i) != 0) {
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crc ^= 0x07;
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}
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}
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ptr++;
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}
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return (crc);
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}
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int st24_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channel_count, uint16_t *channels,
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uint16_t max_chan_count)
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{
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int ret = 1;
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switch (_decode_state) {
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case ST24_DECODE_STATE_UNSYNCED:
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if (byte == ST24_STX1) {
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_decode_state = ST24_DECODE_STATE_GOT_STX1;
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} else {
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ret = 3;
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}
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break;
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case ST24_DECODE_STATE_GOT_STX1:
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if (byte == ST24_STX2) {
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_decode_state = ST24_DECODE_STATE_GOT_STX2;
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} else {
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_decode_state = ST24_DECODE_STATE_UNSYNCED;
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}
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break;
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case ST24_DECODE_STATE_GOT_STX2:
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/* ensure no data overflow failure or hack is possible */
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if ((unsigned)byte <= sizeof(_rxpacket.length) + sizeof(_rxpacket.type) + sizeof(_rxpacket.st24_data)) {
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_rxpacket.length = byte;
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_rxlen = 0;
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_decode_state = ST24_DECODE_STATE_GOT_LEN;
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} else {
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_decode_state = ST24_DECODE_STATE_UNSYNCED;
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}
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break;
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case ST24_DECODE_STATE_GOT_LEN:
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_rxpacket.type = byte;
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_rxlen++;
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_decode_state = ST24_DECODE_STATE_GOT_TYPE;
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break;
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case ST24_DECODE_STATE_GOT_TYPE:
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_rxpacket.st24_data[_rxlen - 1] = byte;
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_rxlen++;
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if (_rxlen == (_rxpacket.length - 1)) {
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_decode_state = ST24_DECODE_STATE_GOT_DATA;
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}
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break;
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case ST24_DECODE_STATE_GOT_DATA:
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_rxpacket.crc8 = byte;
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_rxlen++;
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if (st24_common_crc8((uint8_t *) & (_rxpacket.length), _rxlen) == _rxpacket.crc8) {
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ret = 0;
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/* decode the actual packet */
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switch (_rxpacket.type) {
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case ST24_PACKET_TYPE_CHANNELDATA12: {
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ChannelData12 *d = (ChannelData12 *)_rxpacket.st24_data;
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*rssi = d->rssi;
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*rx_count = d->packet_count;
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/* this can lead to rounding of the strides */
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*channel_count = (max_chan_count < 12) ? max_chan_count : 12;
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unsigned stride_count = (*channel_count * 3) / 2;
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unsigned chan_index = 0;
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for (unsigned i = 0; i < stride_count; i += 3) {
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channels[chan_index] = ((uint16_t)d->channel[i] << 4);
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channels[chan_index] |= ((uint16_t)(0xF0 & d->channel[i + 1]) >> 4);
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/* convert values to 1000-2000 ppm encoding in a not too sloppy fashion */
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channels[chan_index] = (uint16_t)(channels[chan_index] * ST24_SCALE_FACTOR + .5f) + ST24_SCALE_OFFSET;
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chan_index++;
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channels[chan_index] = ((uint16_t)d->channel[i + 2]);
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channels[chan_index] |= (((uint16_t)(0x0F & d->channel[i + 1])) << 8);
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/* convert values to 1000-2000 ppm encoding in a not too sloppy fashion */
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channels[chan_index] = (uint16_t)(channels[chan_index] * ST24_SCALE_FACTOR + .5f) + ST24_SCALE_OFFSET;
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chan_index++;
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}
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}
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break;
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case ST24_PACKET_TYPE_CHANNELDATA24: {
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ChannelData24 *d = (ChannelData24 *)&_rxpacket.st24_data;
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*rssi = d->rssi;
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*rx_count = d->packet_count;
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/* this can lead to rounding of the strides */
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*channel_count = (max_chan_count < 24) ? max_chan_count : 24;
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unsigned stride_count = (*channel_count * 3) / 2;
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unsigned chan_index = 0;
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for (unsigned i = 0; i < stride_count; i += 3) {
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channels[chan_index] = ((uint16_t)d->channel[i] << 4);
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channels[chan_index] |= ((uint16_t)(0xF0 & d->channel[i + 1]) >> 4);
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/* convert values to 1000-2000 ppm encoding in a not too sloppy fashion */
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channels[chan_index] = (uint16_t)(channels[chan_index] * ST24_SCALE_FACTOR + .5f) + ST24_SCALE_OFFSET;
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chan_index++;
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channels[chan_index] = ((uint16_t)d->channel[i + 2]);
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channels[chan_index] |= (((uint16_t)(0x0F & d->channel[i + 1])) << 8);
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/* convert values to 1000-2000 ppm encoding in a not too sloppy fashion */
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channels[chan_index] = (uint16_t)(channels[chan_index] * ST24_SCALE_FACTOR + .5f) + ST24_SCALE_OFFSET;
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chan_index++;
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}
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}
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break;
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case ST24_PACKET_TYPE_TRANSMITTERGPSDATA: {
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// ReceiverFcPacket* d = (ReceiverFcPacket*)&_rxpacket.st24_data;
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/* we silently ignore this data for now, as it is unused */
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ret = 2;
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}
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break;
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default:
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ret = 2;
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break;
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}
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} else {
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/* decoding failed */
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ret = 4;
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}
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_decode_state = ST24_DECODE_STATE_UNSYNCED;
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break;
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}
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return ret;
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}
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