ms2100.c

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/*
 * Copyright (C) 2008-2009 Antoine Drouin <poinix@gmail.com>
 * Copyright (C) 2012 Gautier Hattenberger
 *
 * This file is part of paparazzi.
 *
 * paparazzi 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 2, or (at your option)
 * any later version.
 *
 * paparazzi 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 paparazzi; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */
 
#include "peripherals/ms2100.h"
#include "mcu_periph/spi.h"
 
#include <stdlib.h>  // for abs
 
 
#define MS2100_DIVISOR_128  2
#define MS2100_DIVISOR_256  3
#define MS2100_DIVISOR_512  4
#define MS2100_DIVISOR_1024 5
 
#ifndef MS2100_DIVISOR
#define MS2100_DIVISOR MS2100_DIVISOR_1024
#endif
 
// keep stupid global variable for now...
struct Ms2100 ms2100;
 
 
void ms2100_init(struct Ms2100 *ms, struct spi_periph *spi_p, uint8_t slave_idx)
{
 
  /* set spi_peripheral */
  ms->spi_p = spi_p;
 
  /* configure spi transaction for the request */
  ms->req_trans.cpol = SPICpolIdleLow;
  ms->req_trans.cpha = SPICphaEdge1;
  ms->req_trans.dss = SPIDss8bit;
  ms->req_trans.bitorder = SPIMSBFirst;
  ms->req_trans.cdiv = SPIDiv64;
 
  ms->req_trans.slave_idx = slave_idx;
  ms->req_trans.select = SPISelectUnselect;
  ms->req_trans.output_buf = ms->req_buf;
  ms->req_trans.output_length = 1;
  ms->req_trans.input_buf = NULL;
  ms->req_trans.input_length = 0;
  // ms2100 has to be reset before each measurement: implemented in ms2100_arch.c
  ms->req_trans.before_cb = ms2100_reset_cb;
  ms->req_trans.status = SPITransDone;
 
  /* configure spi transaction to read the result */
  ms->read_trans.cpol = SPICpolIdleLow;
  ms->read_trans.cpha = SPICphaEdge1;
  ms->read_trans.dss = SPIDss8bit;
  ms->read_trans.bitorder = SPIMSBFirst;
  ms->read_trans.cdiv = SPIDiv64;
 
  ms->read_trans.slave_idx = slave_idx;
  ms->read_trans.select = SPISelectUnselect;
  ms->read_trans.output_buf = NULL;
  ms->read_trans.output_length = 0;
  ms->read_trans.input_buf = ms->read_buf;
  ms->read_trans.input_length = 2;
  ms->read_trans.before_cb = NULL;
  ms->read_trans.after_cb = NULL;
  ms->read_trans.status = SPITransDone;
 
  ms2100_arch_init();
 
  INT_VECT3_ZERO(ms->data.vect);
  ms->cur_axe = 0;
 
  ms->status = MS2100_IDLE;
}
 
void ms2100_read(struct Ms2100 *ms)
{
  ms->req_buf[0] = (ms->cur_axe + 1) << 0 | MS2100_DIVISOR << 4;
  spi_submit(ms->spi_p, &(ms->req_trans));
  ms->status = MS2100_SENDING_REQ;
}
 
#define Int16FromBuf(_buf,_idx) ((int16_t)((_buf[_idx]<<8) | _buf[_idx+1]))
 
void ms2100_event(struct Ms2100 *ms)
{
  // handle request transaction
  if (ms->req_trans.status == SPITransDone) {
    if (ms->status == MS2100_GOT_EOC) {
      // eoc occurs, submit reading req
      spi_submit(ms->spi_p, &(ms->read_trans));
      ms->status = MS2100_READING_RES;
    }
  } else if (ms->req_trans.status == SPITransSuccess) {
    ms->req_trans.status = SPITransDone;
  } else if (ms->req_trans.status == SPITransFailed) {
    ms->status = MS2100_IDLE;
    ms->cur_axe = 0;
    ms->req_trans.status = SPITransDone;
  }
 
  // handle reading transaction
  if (ms->read_trans.status == SPITransSuccess) {
    if (ms->status == MS2100_READING_RES) {
      // store value
      int16_t new_val = Int16FromBuf(ms->read_buf, 0);
      // what is this check about?
      if (abs(new_val) < 2000) {
        ms->data.value[ms->cur_axe] = new_val;
      }
      ms->cur_axe++;
      if (ms->cur_axe > 2) {
        ms->cur_axe = 0;
        ms->status = MS2100_DATA_AVAILABLE;
      } else {
        ms->status = MS2100_IDLE;
      }
      ms->read_trans.status = SPITransDone;
    }
  } else if (ms->read_trans.status == SPITransFailed) {
    ms->status = MS2100_IDLE;
    ms->cur_axe = 0;
    ms->read_trans.status = SPITransDone;
  }
}