nuttx/drivers/input/stmpe811_adc.c

/****************************************************************************
 * drivers/input/stmpe811_adc.c
 *
 *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * References:
 *   "STMPE811 S-Touch<63> advanced resistive touchscreen controller with 8-bit
 *    GPIO expander," Doc ID 14489 Rev 6, CD00186725, STMicroelectronics"
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <unistd.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/arch.h>
#include <nuttx/input/stmpe811.h>

#include "stmpe811.h"

#if defined(CONFIG_INPUT) && defined(CONFIG_INPUT_STMPE811) && !defined(CONFIG_STMPE811_ADC_DISABLE)

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: stmpe811_adcinitialize
 *
 * Description:
 *  Configure for ADC mode operation.  Set overall ADC ADC timing that
 *  applies to all pins.
 *
 * Input Parameters:
 *   handle    - The handle previously returned by stmpe811_instantiate
 *
 * Returned Value:
 *   Zero is returned on success.  Otherwise, a negated errno value is
 *   returned to indicate the nature of the failure.
 *
 ****************************************************************************/

int stmpe811_adcinitialize(STMPE811_HANDLE handle)
{
  FAR struct stmpe811_dev_s *priv = (FAR struct stmpe811_dev_s *)handle;
  uint8_t regval;
  int ret;

  DEBUGASSERT(handle);

  /* Get exclusive access to the device structure */

  ret = sem_wait(&priv->exclsem);
  if (ret < 0)
    {
      int errval = errno;
      idbg("sem_wait failed: %d\n", errval);
      return -errval;
    }

  /* Enable Clocking for ADC */

  regval = stmpe811_getreg8(priv, STMPE811_SYS_CTRL2);
  regval &= ~SYS_CTRL2_ADC_OFF;
  stmpe811_putreg8(priv, STMPE811_SYS_CTRL2, regval);

  /* Select Sample Time, bit number and ADC Reference */

  stmpe811_putreg8(priv, STMPE811_ADC_CTRL1, priv->config->ctrl1);

  /* Wait for 20 ms */

  up_mdelay(20);

  /* Select the ADC clock speed */

  stmpe811_putreg8(priv, STMPE811_ADC_CTRL2, priv->config->ctrl2);

  /* Mark ADC initialized */

  priv->flags |= STMPE811_FLAGS_ADC_INITIALIZED;
  sem_post(&priv->exclsem);
  return OK;
}

/****************************************************************************
 * Name: stmpe811_adcconfig
 *
 * Description:
 *  Configure a pin for ADC input.
 *
 * Input Parameters:
 *   handle    - The handle previously returned by stmpe811_instantiate
 *   pin       - The ADC pin number
 *
 * Returned Value:
 *   Zero is returned on success.  Otherwise, a negated errno value is
 *   returned to indicate the nature of the failure.
 *
 ****************************************************************************/

int stmpe811_adcconfig(STMPE811_HANDLE handle, int pin)
{
  FAR struct stmpe811_dev_s *priv = (FAR struct stmpe811_dev_s *)handle;
  uint8_t pinmask = GPIO_PIN(pin);
  uint8_t regval;
  int ret;

  DEBUGASSERT(handle && (unsigned)pin < STMPE811_ADC_NPINS);

  /* Get exclusive access to the device structure */

  ret = sem_wait(&priv->exclsem);
  if (ret < 0)
    {
      int errval = errno;
      idbg("sem_wait failed: %d\n", errval);
      return -errval;
    }

  /* Make sure that the pin is not already in use */

  if ((priv->inuse & pinmask) != 0)
    {
      idbg("PIN%d is already in-use\n", pin);
      sem_post(&priv->exclsem);
      return -EBUSY;
    }

  /* Clear the alternate function bit for the pin, making it an ADC input
   * (or perhaps an an external reference, depending on the state of the
   * ADC_CTRL1_REF_SEL bit).
   */

  regval  = stmpe811_getreg8(priv, STMPE811_GPIO_AF);
  regval &= ~pinmask;
  stmpe811_putreg8(priv, STMPE811_GPIO_AF, regval);

  /* Mark the pin as 'in use' */

  priv->inuse |= pinmask;
  sem_post(&priv->exclsem);
  return OK;
}

/****************************************************************************
 * Name: stmpe811_adcread
 *
 * Description:
 *  Read the converted analog input value from the select pin.
 *
 * Input Parameters:
 *   handle    - The handle previously returned by stmpe811_instantiate
 *   pin       - The ADC pin number
 *
 * Returned Value:
 *   The converted value (there is no error reporting mechanism).
 *
 ****************************************************************************/

uint16_t stmpe811_adcread(STMPE811_HANDLE handle, int pin)
{
  FAR struct stmpe811_dev_s *priv = (FAR struct stmpe811_dev_s *)handle;
  uint8_t pinmask = GPIO_PIN(pin);
  uint8_t regval;
  int i;
  int ret;

  DEBUGASSERT(handle && (unsigned)pin < 8);

  /* Get exclusive access to the device structure */

  ret = sem_wait(&priv->exclsem);
  if (ret < 0)
    {
      int errval = errno;
      idbg("sem_wait failed: %d\n", errval);
      return -errval;
    }

  /* Request AD conversion by setting the bit corresponding the pin in the
   * ADC CAPT register.
   */

  stmpe811_putreg8(priv, STMPE811_ADC_CAPT, pinmask);

  /* Wait for the conversion to complete.  The ADC CAPT register reads '1'
   * if conversion is completed. Reads '0' if conversion is in progress.
   * Try three times before giving up.
   */

  for (i = 0; i < 3; i++)
    {
      /* The worst case ADC conversion time is (nominally) 56.4 uS. The
       * following usleep() looks nice but in reality, the usleep()
       * does not have that kind of precision (it will probably end up
       * waiting 10 MS).
       */

      usleep(57);

      /* Check if the conversion is complete */

      regval = stmpe811_getreg8(priv, STMPE811_ADC_CAPT);
      if ((regval & pinmask) != 0)
        {
          break;
        }
    }

  /* At the completion of the conversion, return whatever we read from
   * from the channel register associated with the pin.
   */
 
  return stmpe811_getreg16(priv, STMPE811_ADC_DATACH(pin));
}

#endif /* CONFIG_INPUT && CONFIG_INPUT_STMPE811 && !CONFIG_STMPE811_ADC_DISABLE */