ardupilot/libraries/AP_RCProtocol/AP_RCProtocol_SRXL.h

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/*
* This file is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This file is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Code by Andrew Tridgell and Siddharth Bharat Purohit
*/
#pragma once
#include "AP_RCProtocol_config.h"
#if AP_RCPROTOCOL_SRXL_ENABLED
#include "AP_RCProtocol.h"
#include "SoftSerial.h"
#define SRXL_MIN_FRAMESPACE_US 8000U /* Minumum space between srxl frames in us (applies to all variants) */
#define SRXL_MAX_CHANNELS 20U /* Maximum number of channels from srxl datastream */
/* Variant specific SRXL datastream characteristics */
/* Framelength in byte */
#define SRXL_FRAMELEN_V1 27U /* Framelength with header in byte for: Mpx SRXLv1 or XBUS Mode B */
#define SRXL_FRAMELEN_V2 35U /* Framelength with header in byte for: Mpx SRXLv2 */
#define SRXL_FRAMELEN_V5 18U /* Framelength with header in byte for Spk AR7700 etc. */
#define SRXL_FRAMELEN_MAX 35U /* maximum possible framelengh */
/* Headerbyte */
#define SRXL_HEADER_V1 0xA1U /* Headerbyte for: Mpx SRXLv1 or XBUS Mode B */
#define SRXL_HEADER_V2 0xA2U /* Headerbyte for: Mpx SRXLv2 */
#define SRXL_HEADER_V5 0xA5U /* Headerbyte for: Spk AR7700 etc. */
#define SRXL_HEADER_NOT_IMPL 0xFFU /* Headerbyte for non impemented srxl header*/
class AP_RCProtocol_SRXL : public AP_RCProtocol_Backend {
public:
AP_RCProtocol_SRXL(AP_RCProtocol &_frontend) : AP_RCProtocol_Backend(_frontend) {}
void process_pulse(uint32_t width_s0, uint32_t width_s1) override;
void process_byte(uint8_t byte, uint32_t baudrate) override;
private:
void _process_byte(uint32_t timestamp_us, uint8_t byte);
int srxl_channels_get_v1v2(uint16_t max_values, uint8_t *num_values, uint16_t *values, bool *failsafe_state);
int srxl_channels_get_v5(uint16_t max_values, uint8_t *num_values, uint16_t *values, bool *failsafe_state);
uint8_t buffer[SRXL_FRAMELEN_MAX]; /* buffer for raw srxl frame data in correct order --> buffer[0]=byte0 buffer[1]=byte1 */
uint8_t buflen; /* length in number of bytes of received srxl dataframe in buffer */
uint32_t last_data_us; /* timespan since last received data in us */
uint16_t channels[SRXL_MAX_CHANNELS] = {0}; /* buffer for extracted RC channel data as pulsewidth in microseconds */
uint16_t max_channels = 0;
enum {
STATE_IDLE, /* do nothing */
STATE_NEW, /* get header of frame + prepare for frame reception + begin new crc cycle */
STATE_COLLECT /* collect RC channel data from frame + concurrently calc crc over payload data + extract channel information */
};
uint8_t frame_header = 0U; /* Frame header from SRXL datastream */
uint8_t frame_len_full = 0U; /* Length in number of bytes of full srxl datastream */
uint8_t decode_state = STATE_IDLE; /* Current state of SRXL frame decoding */
uint8_t decode_state_next = STATE_IDLE; /* State of frame decoding thatwill be applied when the next byte from dataframe drops in */
uint16_t crc_fmu = 0U; /* CRC calculated over payload from srxl datastream on this machine */
uint16_t crc_receiver = 0U; /* CRC extracted from srxl datastream */
SoftSerial ss{115200, SoftSerial::SERIAL_CONFIG_8N1};
};
#endif // AP_RCPROTOCOL_SRXL_ENABLED