flight/pios/inc/pios_srxl_priv.h

   1 /**
   2  ******************************************************************************
   3  * @addtogroup PIOS PIOS Core hardware abstraction layer
   4  * @{
   5  * @addtogroup PIOS_SRXL Multiplex SRXL receiver functions
   6  * @brief Code to read Multiplex SRXL receiver serial stream
   7  * @{
   8  *
   9  * @file       pios_srxl_priv.h
  10  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2015.
  11  * @brief      Code to read Multiplex SRXL receiver serial stream
  12  * @see        The GNU Public License (GPL) Version 3
  13  *
  14  *****************************************************************************/
  15 /*
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 3 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful, but
  22  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  23  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  24  * for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License along
  27  * with this program; if not, write to the Free Software Foundation, Inc.,
  28  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  29  */
  30
  31 #ifndef PIOS_SRXL_PRIV_H
  32 #define PIOS_SRXL_PRIV_H
  33
  34 #include <pios.h>
  35 #include <pios_stm32.h>
  36 #include <pios_usart_priv.h>
  37
  38 /*
  39  * Multiplex SRXL serial port settings:
  40  *  115200bps inverted serial stream, 8 bits, no parity, 1 stop bits
  41  *  frame period is 14ms (FastResponse ON) or 21ms (FastResponse OFF)
  42  *
  43  * Frame structure:
  44  *  1 byte  - start and version
  45  *      0xa1 (v1 12-channels)
  46  *      0xa2 (v2 16-channels)
  47  * 24/32 bytes - channel data (4 + 12 bit/channel, 12/16 channels, MSB first)
  48  *      16 bits per channel. 4 first reserved/not used. 12 bits channel data in
  49  *          4095 steps, 0x000(800µs) - 0x800(1500µs) - 0xfff(2200µs)
  50  *  2 bytes checksum (calculated over all bytes including start and version)
  51  *
  52  * Checksum calculation:
  53  * u16 CRC16(u16 crc, u8 value) {
  54  *     u8 i;
  55  *     crc = crc ^ (s16)value << 8;
  56  *     for(i = 0; i < 8; i++) {
  57  *         if(crc & 0x8000) {
  58  *             crc = crc << 1 ^ 0x1021;
  59  *         } else {
  60  *             crc = crc << 1;
  61  *         }
  62  *     }
  63  *     return crc;
  64  * }
  65  */
  66
  67 #define SRXL_V1_HEADER             0xa1
  68 #define SRXL_V2_HEADER             0xa2
  69
  70 #define SRXL_HEADER_LENGTH         1
  71 #define SRXL_CHECKSUM_LENGTH       2
  72 #define SRXL_V1_CHANNEL_DATA_BYTES (12 * 2)
  73 #define SRXL_V2_CHANNEL_DATA_BYTES (16 * 2)
  74 #define SRXL_FRAME_LENGTH          (SRXL_HEADER_LENGTH + SRXL_V2_CHANNEL_DATA_BYTES + SRXL_CHECKSUM_LENGTH)
  75
  76 /*
  77  * Multiplex SRXL protocol provides 16 proportional channels.
  78  * Do not change unless driver code is updated accordingly.
  79  */
  80 #if (PIOS_SRXL_NUM_INPUTS != 16)
  81 #error "Multiplex SRXL protocol provides 16 proportional channels."
  82 #endif
  83
  84 extern const struct pios_rcvr_driver pios_srxl_rcvr_driver;
  85
  86 extern int32_t PIOS_SRXL_Init(uint32_t *srxl_id,
  87                               const struct pios_com_driver *driver,
  88                               uint32_t lower_id);
  89
  90 #endif /* PIOS_SRXL_PRIV_H */
  91
  92 /**
  93  * @}
  94  * @}
  95  */