Line data    Source code

       1             : /*
       2             :  * This file is free software: you can redistribute it and/or modify it
       3             :  * under the terms of the GNU General Public License as published by the
       4             :  * Free Software Foundation, either version 3 of the License, or
       5             :  * (at your option) any later version.
       6             :  *
       7             :  * This file is distributed in the hope that it will be useful, but
       8             :  * WITHOUT ANY WARRANTY; without even the implied warranty of
       9             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
      10             :  * See the GNU General Public License for more details.
      11             :  *
      12             :  * You should have received a copy of the GNU General Public License along
      13             :  * with this program.  If not, see <http://www.gnu.org/licenses/>.
      14             :  *
      15             :  * Code by Andrew Tridgell and Siddharth Bharat Purohit
      16             :  */
      17             : 
      18             : #pragma once
      19             : 
      20             : #include "AP_RCProtocol_config.h"
      21             : 
      22             : #if AP_RCPROTOCOL_SRXL_ENABLED
      23             : 
      24             : #include "AP_RCProtocol.h"
      25             : #include "SoftSerial.h"
      26             : 
      27             : #define SRXL_MIN_FRAMESPACE_US 8000U    /* Minumum space between srxl frames in us (applies to all variants)  */
      28             : #define SRXL_MAX_CHANNELS 20U           /* Maximum number of channels from srxl datastream  */
      29             : 
      30             : /* Variant specific SRXL datastream characteristics */
      31             : /* Framelength in byte */
      32             : #define SRXL_FRAMELEN_V1    27U      /* Framelength with header in byte for:  Mpx SRXLv1 or XBUS Mode B */
      33             : #define SRXL_FRAMELEN_V2    35U      /* Framelength with header in byte for:  Mpx SRXLv2 */
      34             : #define SRXL_FRAMELEN_V5    18U      /* Framelength with header in byte for  Spk AR7700 etc. */
      35             : #define SRXL_FRAMELEN_MAX   35U      /* maximum possible framelengh  */
      36             : 
      37             : /* Headerbyte */
      38             : #define SRXL_HEADER_V1          0xA1U    /* Headerbyte for:  Mpx SRXLv1 or XBUS Mode B */
      39             : #define SRXL_HEADER_V2          0xA2U    /* Headerbyte for:  Mpx SRXLv2  */
      40             : #define SRXL_HEADER_V5          0xA5U    /* Headerbyte for:  Spk AR7700 etc. */
      41             : #define SRXL_HEADER_NOT_IMPL    0xFFU    /* Headerbyte for non impemented srxl header*/
      42             : 
      43             : class AP_RCProtocol_SRXL : public AP_RCProtocol_Backend {
      44             : public:
      45        2094 :     AP_RCProtocol_SRXL(AP_RCProtocol &_frontend) : AP_RCProtocol_Backend(_frontend) {}
      46             :     void process_pulse(uint32_t width_s0, uint32_t width_s1) override;
      47             :     void process_byte(uint8_t byte, uint32_t baudrate) override;
      48             : private:
      49             :     void _process_byte(uint32_t timestamp_us, uint8_t byte);
      50             :     int srxl_channels_get_v1v2(uint16_t max_values, uint8_t *num_values, uint16_t *values, bool *failsafe_state);
      51             :     int srxl_channels_get_v5(uint16_t max_values, uint8_t *num_values, uint16_t *values, bool *failsafe_state);
      52             :     uint8_t buffer[SRXL_FRAMELEN_MAX];       /* buffer for raw srxl frame data in correct order --> buffer[0]=byte0  buffer[1]=byte1  */
      53             :     uint8_t buflen;                          /* length in number of bytes of received srxl dataframe in buffer  */
      54             :     uint32_t last_data_us;                   /* timespan since last received data in us   */
      55             :     uint16_t channels[SRXL_MAX_CHANNELS] = {0};    /* buffer for extracted RC channel data as pulsewidth in microseconds */
      56             :     uint16_t max_channels = 0;
      57             :     enum {
      58             :         STATE_IDLE,                          /* do nothing */
      59             :         STATE_NEW,                           /* get header of frame + prepare for frame reception + begin new crc cycle   */
      60             :         STATE_COLLECT                        /* collect RC channel data from frame + concurrently calc crc over payload data + extract channel information */
      61             :     };
      62             :     uint8_t frame_header = 0U;                   /* Frame header from SRXL datastream    */
      63             :     uint8_t frame_len_full = 0U;                 /* Length in number of bytes of full srxl datastream */
      64             :     uint8_t decode_state = STATE_IDLE;           /* Current state of SRXL frame decoding */
      65             :     uint8_t decode_state_next = STATE_IDLE;      /* State of frame decoding thatwill be applied when the next byte from dataframe drops in  */
      66             :     uint16_t crc_fmu = 0U;                       /* CRC calculated over payload from srxl datastream on this machine */
      67             :     uint16_t crc_receiver = 0U;                  /* CRC extracted from srxl datastream  */
      68             : 
      69             :     SoftSerial ss{115200, SoftSerial::SERIAL_CONFIG_8N1};
      70             : };
      71             : 
      72             : #endif  // AP_RCPROTOCOL_SRXL_ENABLED