flight/pios/common/pios_ms4525do.c

   1 /**
   2  ******************************************************************************
   3  * @addtogroup PIOS PIOS Core hardware abstraction layer
   4  * @{
   5  * @addtogroup PIOS_MS4525DO MS4525DO Functions
   6  * @brief Hardware functions to deal with the PixHawk Airspeed Sensor based on MS4525DO
   7  * @{
   8  *
   9  * @file       pios_ms4525do.c
  10  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2014.
  11  * @brief      PixHawk MS4525DO Airspeed Sensor Driver
  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
  32 #include "pios.h"
  33
  34 #ifdef PIOS_INCLUDE_MS4525DO
  35
  36 /* Local Defs and Variables */
  37
  38
  39 static int8_t PIOS_MS4525DO_ReadI2C(uint8_t *buffer, uint8_t len)
  40 {
  41     const struct pios_i2c_txn txn_list[] = {
  42         {
  43             .info = __func__,
  44             .addr = MS4525DO_I2C_ADDR,
  45             .rw   = PIOS_I2C_TXN_READ,
  46             .len  = len,
  47             .buf  = buffer,
  48         }
  49     };
  50
  51     return PIOS_I2C_Transfer(PIOS_I2C_MS4525DO_ADAPTER, txn_list, NELEMENTS(txn_list));
  52 }
  53
  54
  55 // values has to ba an arrray with two elements
  56 // values stay untouched on error
  57 int8_t PIOS_MS4525DO_Read(uint16_t *values)
  58 {
  59     uint8_t data[4];
  60     int8_t retVal  = PIOS_MS4525DO_ReadI2C(data, sizeof(data));
  61
  62     uint8_t status = data[0] & 0xC0;
  63
  64     if (status == 0x80) {
  65         /* stale data */
  66         return -5;
  67     } else if (status == 0xC0) {
  68         /* device probably broken */
  69         return -6;
  70     }
  71
  72     /* differential pressure */
  73     values[0]  = (data[0] << 8);
  74     values[0] += data[1];
  75
  76     /* temperature */
  77     values[1]  = (data[2] << 8);
  78     values[1] += data[3];
  79     values[1]  = (values[1] >> 5);
  80
  81     return retVal;
  82 }
  83
  84 #endif /* PIOS_INCLUDE_MS4525DO */