/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT 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 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/
/*
   Concepts and parts of this file have been contributed by Uladzimir Pylinsky
   aka barthess.
 */

/**
 * This demo acquire data from accelerometer and prints it in shell.
 */

#include <stdlib.h>

#include "ch.h"
#include "hal.h"

/* buffers depth */
#define ACCEL_RX_DEPTH 6
#define ACCEL_TX_DEPTH 4

/* mma8451q specific addresses */
#define ACCEL_OUT_DATA    0x01
#define ACCEL_CTRL_REG1   0x2A

static uint8_t rxbuf[ACCEL_RX_DEPTH];
static uint8_t txbuf[ACCEL_TX_DEPTH];
static i2cflags_t errors = 0;
static int16_t acceleration_x, acceleration_y, acceleration_z;
#define mma8451_addr 0b0011100

/**
 *
 */
static void print(char *p) {

  while (*p) {
    sdPut(&SD2, *p++);
  }
}

/**
 *
 */
static void println(char *p) {

  while (*p) {
    sdPut(&SD2, *p++);
  }
  sdWriteTimeout(&SD2, (uint8_t *)"\r\n", 2, TIME_INFINITE);
}

/**
 *
 */
static void printn(int16_t n) {
  char buf[16], *p;

  if (n > 0)
    sdPut(&SD2, '+');
  else{
    sdPut(&SD2, '-');
    n = abs(n);
  }

  if (!n)
    sdPut(&SD2, '0');
  else {
    p = buf;
    while (n)
      *p++ = (n % 10) + '0', n /= 10;
    while (p > buf)
      sdPut(&SD2, *--p);
  }
}

/**
 * Converts data from 2complemented representation to signed integer
 */
int16_t complement2signed(uint8_t msb, uint8_t lsb){
  uint16_t word = 0;
  word = (msb << 8) + lsb;
  if (msb > 0x7F){
    return -1 * ((int16_t)((~word) + 1));
  }
  return (int16_t)word;
}

/* I2C interface #2 */
static const I2CConfig i2cfg2 = {
    OPMODE_I2C,
    400000,
    FAST_DUTY_CYCLE_2,
};

/*
 * Application entry point.
 */
int main(void) {
  msg_t status = RDY_OK;
  systime_t tmo = MS2ST(4);

  /*
   * System initializations.
   * - HAL initialization, this also initializes the configured device drivers
   *   and performs the board-specific initializations.
   * - Kernel initialization, the main() function becomes a thread and the
   *   RTOS is active.
   */
  halInit();
  chSysInit();

  /*
   * Starts I2C
   */
  i2cStart(&I2CD2, &i2cfg2);

  /*
   * Prepares the Serial driver 2
   */
  sdStart(&SD2, NULL);          /* Default is 38400-8-N-1.*/
  palSetPadMode(GPIOA, 2, PAL_MODE_ALTERNATE(7));
  palSetPadMode(GPIOA, 3, PAL_MODE_ALTERNATE(7));

  /**
   * Prepares the accelerometer
   */
  txbuf[0] = ACCEL_CTRL_REG1; /* register address */
  txbuf[1] = 0x1;
  i2cAcquireBus(&I2CD2);
  status = i2cMasterTransmitTimeout(&I2CD2, mma8451_addr, txbuf, 2, rxbuf, 0, tmo);
  i2cReleaseBus(&I2CD2);

  if (status != RDY_OK){
    errors = i2cGetErrors(&I2CD2);
  }

  /*
   * Normal main() thread activity, nothing in this test.
   */
  while (TRUE) {
    palTogglePad(GPIOB, GPIOB_LED_B);
    chThdSleepMilliseconds(100);

    txbuf[0] = ACCEL_OUT_DATA; /* register address */
    i2cAcquireBus(&I2CD2);
    status = i2cMasterTransmitTimeout(&I2CD2, mma8451_addr, txbuf, 1, rxbuf, 6, tmo);
    i2cReleaseBus(&I2CD2);

    if (status != RDY_OK){
      errors = i2cGetErrors(&I2CD2);
    }

    acceleration_x = complement2signed(rxbuf[0], rxbuf[1]);
    acceleration_y = complement2signed(rxbuf[2], rxbuf[3]);
    acceleration_z = complement2signed(rxbuf[4], rxbuf[5]);

    print("x: ");
    printn(acceleration_x);
    print(" y: ");
    printn(acceleration_y);
    print(" z: ");
    printn(acceleration_z);
    println("");
  }
}