modules/devices/encoders/encoders_spi/encoders_spi.c

   1 /*
   2  *  Copyright Droids Corporation (2009)
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2 of the License, or
   7  *  (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, write to the Free Software
  16  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  *
  18  *  Revision : $Id: encoders_spi.c,v 1.1.2.3 2009-04-07 20:00:46 zer0 Exp $
  19  *
  20  *  Olivier MATZ <zer0@droids-corp.org>
  21  */
  22
  23 /* This modules handles encoders: values are read through a SPI
  24  * interface. Basically, frames are formatted with 4 words of 16 bits,
  25  * describing the values of the 4 encoders. */
  26
  27 #ifndef HOST_VERSION
  28
  29 #include <string.h>
  30
  31 #include <aversive.h>
  32 #include <aversive/parts.h>
  33
  34 #include <spi.h>
  35
  36 #include <encoders_spi.h>
  37 #include <encoders_spi_config.h>
  38
  39 static int32_t g_encoders_spi_values[ENCODERS_SPI_NUMBER];
  40 static int16_t g_encoders_spi_previous[ENCODERS_SPI_NUMBER];
  41
  42
  43 /* Initialisation of encoders, variables */
  44 void encoders_spi_init(void)
  45 {
  46         memset(g_encoders_spi_previous, 0, sizeof(g_encoders_spi_previous));
  47         spi_register_ss_line(&ENCODERS_SPI_SS_PORT, ENCODERS_SPI_SS_BIT);
  48         spi_init(SPI_MODE_MASTER, ENCODERS_SPI_FORMAT, ENCODERS_SPI_CLK_RATE);
  49         spi_set_data_order(ENCODERS_SPI_DATA_ORDER);
  50         encoders_spi_manage(NULL);
  51         memset(g_encoders_spi_values, 0, sizeof(g_encoders_spi_values));
  52 }
  53
  54
  55 /* Update encoders values */
  56 void encoders_spi_manage(__attribute__((unused)) void *dummy)
  57 {
  58         union {
  59                 struct {
  60                         uint8_t u8_lsb;
  61                         uint8_t u8_msb;
  62                 } s;
  63                 int16_t s16;
  64         } enc;
  65         uint8_t i;
  66         int16_t diff;
  67         uint8_t flags;
  68
  69         spi_slave_select(0);
  70         for (i=0; i<ENCODERS_SPI_NUMBER; i++) {
  71                 enc.s.u8_lsb = spi_receive_byte();
  72                 enc.s.u8_msb = spi_receive_byte();
  73                 diff = enc.s16 - g_encoders_spi_previous[i];
  74                 g_encoders_spi_previous[i] = enc.s16;
  75                 IRQ_LOCK(flags);
  76                 g_encoders_spi_values[i] += diff;
  77                 IRQ_UNLOCK(flags);
  78         }
  79         spi_slave_deselect(0);
  80 }
  81
  82
  83
  84 /* Extract encoder value */
  85 int32_t encoders_spi_get_value(void *encoder)
  86 {
  87         int32_t value;
  88         uint8_t flags;
  89
  90         IRQ_LOCK(flags);
  91         value = g_encoders_spi_values[(int)encoder];
  92         IRQ_UNLOCK(flags);
  93
  94         return value;
  95 }
  96
  97 /* Set an encoder value */
  98 void encoders_spi_set_value(void *encoder, int32_t val)
  99 {
 100         uint8_t flags;
 101
 102         IRQ_LOCK(flags);
 103         g_encoders_spi_values[(int)encoder] = val;
 104         IRQ_UNLOCK(flags);
 105 }
 106
 107 #endif