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nuttx/drivers/analog/ads1242.c

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/****************************************************************************
* drivers/sensors/ads1242.c
* Character driver for the MCP3426 Differential Input 16 Bit Delta/Sigma ADC
*
* Copyright (C) 2015 DS-Automotion GmbH. All rights reserved.
* Author: Alexander Entinger <a.entinger@ds-automotion.com>
*
* 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 <stdlib.h>
#include <stdbool.h>
#include <fixedmath.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/spi/spi.h>
#include <nuttx/analog/ads1242.h>
#if defined(CONFIG_SPI) && defined(CONFIG_ADC_ADS1242)
/****************************************************************************
* Private Types
****************************************************************************/
struct ads1242_dev_s
{
FAR struct spi_dev_s *spi; /* Pointer to the SPI instance */
uint32_t osc_period_us; /* Period of the oscillator attached to the ADS1242 in us */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* SPI Helpers */
static void ads1242_reset(FAR struct ads1242_dev_s *dev);
static void ads1242_performSelfGainCalibration(
FAR struct ads1242_dev_s *dev);
static void ads1242_performSelfOffsetCalibration(
FAR struct ads1242_dev_s *dev);
static void ads1242_performSystemOffsetCalibration(
FAR struct ads1242_dev_s *dev);
static void ads1242_read_conversion_result(FAR struct ads1242_dev_s *dev,
FAR uint32_t *conversion_result);
static void ads1242_write_reg(FAR struct ads1242_dev_s *dev,
uint8_t const reg_addr, uint8_t const reg_value);
static void ads1242_read_reg(FAR struct ads1242_dev_s *dev,
uint8_t const reg_addr, FAR uint8_t *reg_value);
static void ads1242_set_gain(FAR struct ads1242_dev_s *dev,
ADS1242_GAIN_SELECTION const gain_selection);
static void ads1242_set_positive_input(FAR struct ads1242_dev_s *dev,
ADS1242_POSITIVE_INPUT_SELECTION const pos_in_sel);
static void ads1242_set_negative_input(FAR struct ads1242_dev_s *dev,
ADS1242_NEGATIVE_INPUT_SELECTION const neg_in_sel);
static bool ads1242_is_data_ready(FAR struct ads1242_dev_s *dev);
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_VERBOSE)
static void ads1242_print_regs(FAR struct ads1242_dev_s *dev, char const *msg);
#endif /* CONFIG_DEBUG && CONFIG_DEBUG_VERBOSE */
/* Character driver methods */
static int ads1242_open(FAR struct file *filep);
static int ads1242_close(FAR struct file *filep);
static ssize_t ads1242_read(FAR struct file *, FAR char *, size_t);
static ssize_t ads1242_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int ads1242_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_ads1242_fops =
{
ads1242_open,
ads1242_close,
ads1242_read,
ads1242_write,
NULL,
ads1242_ioctl
#ifndef CONFIG_DISABLE_POLL
, NULL
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: ads1242_reset
****************************************************************************/
static void ads1242_reset(FAR struct ads1242_dev_s *dev)
{
SPI_SELECT(dev->spi, 0, true); /* Set nADC_SPI_CS to low which selects the ADS1242 */
SPI_SEND(dev->spi, ADS1242_CMD_RESET);/* Issue reset command */
SPI_SELECT(dev->spi, 0, false); /* Set nADC_SPI_CS to high which deselects the ADS1242 */
up_mdelay(100); /* Wait a little so the device has time to perform a proper reset */
}
/****************************************************************************
* Name: ads1242_performSelfGainCalibration
****************************************************************************/
static void ads1242_performSelfGainCalibration(FAR struct ads1242_dev_s *dev)
{
SPI_SELECT(dev->spi, 0, true);
SPI_SEND(dev->spi, ADS1242_CMD_SELF_GAIN_CALIB);
SPI_SELECT(dev->spi, 0, false);
}
/****************************************************************************
* Name: ads1242_performSelfOffsetCalibration
****************************************************************************/
static void ads1242_performSelfOffsetCalibration(FAR struct ads1242_dev_s *dev)
{
SPI_SELECT(dev->spi, 0, true);
SPI_SEND(dev->spi, ADS1242_CMD_SELF_OFFSET_CALIB);
SPI_SELECT(dev->spi, 0, false);
}
/****************************************************************************
* Name: ads1242_performSystemOffsetCalibration
****************************************************************************/
static void
ads1242_performSystemOffsetCalibration(FAR struct ads1242_dev_s *dev)
{
SPI_SELECT(dev->spi, 0, true);
SPI_SEND(dev->spi, ADS1242_CMD_SYSTEM_OFFSET_CALIB);
SPI_SELECT(dev->spi, 0, false);
}
/****************************************************************************
* Name: ads1242_read_conversion_result
****************************************************************************/
static void ads1242_read_conversion_result(FAR struct ads1242_dev_s *dev,
FAR uint32_t *conversion_result)
{
SPI_SELECT(dev->spi, 0, true);
SPI_SEND(dev->spi, ADS1242_CMD_READ_DATA);
/* Delay between last SCLK edge for DIN and first SCLK edge for DOUT:
* RDATA, RDATAC, RREG, WREG: Min 50 x tOSC Periods
*/
up_udelay(50 * dev->osc_period_us);
*conversion_result = 0;
/* 1st Byte = MSB
* 2nd Byte = Mid-Byte
* 3rd Byte = LSB
*/
*conversion_result |= ((uint32_t)(SPI_SEND(dev->spi, 0xFF))) << 16;
*conversion_result |= ((uint32_t)(SPI_SEND(dev->spi, 0xFF))) << 8;
*conversion_result |= ((uint32_t)(SPI_SEND(dev->spi, 0xFF))) << 0;
SPI_SELECT(dev->spi, 0, false);
}
/****************************************************************************
* Name: ads1242_write_reg
*
* Description:
* Write to the registers starting with the register address specified as
* part of the instruction. The number of registers that will be written
* is one plus the value of the second byte.
*
****************************************************************************/
static void ads1242_write_reg(FAR struct ads1242_dev_s *dev,
uint8_t const reg_addr, uint8_t const reg_value)
{
SPI_SELECT(dev->spi, 0, true);
SPI_SEND(dev->spi, ADS1242_CMD_WRITE_REGISTER | reg_addr);
SPI_SEND(dev->spi, 0x00); /* Write 1 Byte */
SPI_SEND(dev->spi, reg_value);
SPI_SELECT(dev->spi, 0, false);
}
/****************************************************************************
* Name: ads1242_read_reg
*
* Description:
* Output the data from up to 16 registers starting with the register
* address specified as part of the instruction. The number of registers
* read will be one plus the second byte count. If the count exceeds the
* remaining registers, the addresses wrap back to the beginning.
*
****************************************************************************/
static void ads1242_read_reg(FAR struct ads1242_dev_s *dev,
uint8_t const reg_addr, FAR uint8_t *reg_value)
{
SPI_SELECT(dev->spi, 0, true);
SPI_SEND(dev->spi, ADS1242_CMD_READ_REGISTER | reg_addr);
SPI_SEND(dev->spi, 0x00); /* Read 1 Byte */
/* Delay between last SCLK edge for DIN and first SCLK edge for DOUT:
* RDATA, RDATAC, RREG, WREG: Min 50 x tOSC Periods
*/
up_udelay(50 * dev->osc_period_us);
*reg_value = SPI_SEND(dev->spi, 0xFF);
SPI_SELECT(dev->spi, 0, false);
}
/****************************************************************************
* Name: ads1242_set_gain
****************************************************************************/
static void ads1242_set_gain(FAR struct ads1242_dev_s *dev,
ADS1242_GAIN_SELECTION const gain_selection)
{
uint8_t setup_reg_value = 0;
ads1242_read_reg(dev, ADS1242_REG_SETUP, &setup_reg_value);
setup_reg_value &= ~(ADS1242_REG_SETUP_BIT_PGA2 |
ADS1242_REG_SETUP_BIT_PGA1 |
ADS1242_REG_SETUP_BIT_PGA0);
setup_reg_value |= (uint8_t)(gain_selection);
ads1242_write_reg(dev, ADS1242_REG_SETUP, setup_reg_value);
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_VERBOSE)
ads1242_print_regs(dev, "ads1242_set_gain");
#endif
/* It is necessary to perform a offset calibration after setting the gain */
ads1242_performSelfOffsetCalibration(dev);
}
/****************************************************************************
* Name: ads1242_set_positive_input
****************************************************************************/
static void ads1242_set_positive_input(FAR struct ads1242_dev_s *dev,
ADS1242_POSITIVE_INPUT_SELECTION const pos_in_sel)
{
uint8_t mux_reg_value = 0;
ads1242_read_reg(dev, ADS1242_REG_MUX, &mux_reg_value);
mux_reg_value &= ~(ADS1242_REG_MUX_BIT_PSEL3 | ADS1242_REG_MUX_BIT_PSEL2 |
ADS1242_REG_MUX_BIT_PSEL1 | ADS1242_REG_MUX_BIT_PSEL0);
mux_reg_value |= (uint8_t)(pos_in_sel);
ads1242_write_reg(dev, ADS1242_REG_MUX, mux_reg_value);
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_VERBOSE)
ads1242_print_regs(dev, "ads1242_set_positive_input");
#endif
}
/****************************************************************************
* Name: ads1242_set_negative_input
****************************************************************************/
static void ads1242_set_negative_input(FAR struct ads1242_dev_s *dev,
ADS1242_NEGATIVE_INPUT_SELECTION const neg_in_sel)
{
uint8_t mux_reg_value = 0;
ads1242_read_reg(dev, ADS1242_REG_MUX, &mux_reg_value);
mux_reg_value &= ~(ADS1242_REG_MUX_BIT_NSEL3 | ADS1242_REG_MUX_BIT_NSEL2 |
ADS1242_REG_MUX_BIT_NSEL1 | ADS1242_REG_MUX_BIT_NSEL0);
mux_reg_value |= (uint8_t)(neg_in_sel);
ads1242_write_reg(dev, ADS1242_REG_MUX, mux_reg_value);
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_VERBOSE)
ads1242_print_regs(dev, "ads1242_set_negative_input");
#endif
}
/****************************************************************************
* Name: ads1242_set_negative_input
****************************************************************************/
static bool ads1242_is_data_ready(FAR struct ads1242_dev_s *dev)
{
uint8_t acr_reg_value = 0xFF;
ads1242_read_reg(dev, ADS1242_REG_ACR, &acr_reg_value);
return (acr_reg_value & ADS1242_REG_ACR_BIT_nDRDY) == 0;
}
/****************************************************************************
* Name: ads1242_print_regs
****************************************************************************/
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_VERBOSE)
static void ads1242_print_regs(FAR struct ads1242_dev_s *dev, char const *msg)
{
uint8_t setup_reg_value = 0;
uint8_t mux_reg_value = 0;
uint8_t acr_reg_value = 0;
dbg("%s\n", msg);
ads1242_read_reg(dev, ADS1242_REG_SETUP, &setup_reg_value);
ads1242_read_reg(dev, ADS1242_REG_MUX, &mux_reg_value);
ads1242_read_reg(dev, ADS1242_REG_ACR, &acr_reg_value);
dbg("SETUP %02X\n", setup_reg_value);
dbg("MUX %02X\n", mux_reg_value);
dbg("ACR %02X\n", acr_reg_value);
}
#endif /* CONFIG_DEBUG && CONFIG_DEBUG_VERBOSE */
/****************************************************************************
* Name: ads1242_open
****************************************************************************/
static int ads1242_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct ads1242_dev_s *priv = inode->i_private;
ads1242_reset(priv);
up_mdelay(100);
ads1242_performSelfGainCalibration(priv);
up_mdelay(100);
/* SPEED = 1 -> fMod = fOsc / 256 (fMod = Modulator Clock Speed)
* BUFEN = 1 -> Internal input buffer enabled -> results in a very high
* impedance input for the ADC ~ 5 GOhm
*/
ads1242_write_reg(priv, ADS1242_REG_ACR,
ADS1242_REG_ACR_BIT_SPEED | ADS1242_REG_ACR_BIT_BUFEN);
ads1242_performSelfOffsetCalibration(priv);
up_mdelay(100);
#if defined(CONFIG_DEBUG) && defined(CONFIG_DEBUG_VERBOSE)
ads1242_print_regs(priv, "ads1242_open");
#endif
return OK;
}
/****************************************************************************
* Name: ads1242_close
****************************************************************************/
static int ads1242_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct ads1242_dev_s *priv = inode->i_private;
ads1242_reset(priv);
up_mdelay(100);
return OK;
}
/****************************************************************************
* Name: ads1242_read
****************************************************************************/
static ssize_t ads1242_read(FAR struct file *filep,
FAR char *buffer, size_t buflen)
{
return -ENOSYS;
}
/****************************************************************************
* Name: ads1242_write
****************************************************************************/
static ssize_t ads1242_write(FAR struct file *filep,
FAR const char *buffer, size_t buflen)
{
return -ENOSYS;
}
/****************************************************************************
* Name: ads1242_ioctl
****************************************************************************/
static int ads1242_ioctl (FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct ads1242_dev_s *priv = inode->i_private;
int ret = OK;
switch (cmd)
{
/* Read the result of an analog conversion */
case ANIOC_ADS2142_READ:
{
FAR uint32_t *data = (FAR uint32_t *)((uintptr_t)arg);
ads1242_read_conversion_result(priv, data);
}
break;
/* Set the gain of the ADC */
case ANIOC_ADS2142_SET_GAIN:
{
ads1242_set_gain(priv, (ADS1242_GAIN_SELECTION)(arg));
}
break;
/* Set the positive input of the ADC */
case ANIOC_ADS2142_SET_POSITIVE_INPUT:
{
ads1242_set_positive_input(priv,
(ADS1242_POSITIVE_INPUT_SELECTION)(arg));
}
break;
/* Set the negative input of the ADC */
case ANIOC_ADS2142_SET_NEGATIVE_INPUT:
{
ads1242_set_negative_input(priv,
(ADS1242_NEGATIVE_INPUT_SELECTION)(arg));
}
break;
/* Check if data is ready to be read */
case ANIOC_ADS2142_IS_DATA_READY:
{
FAR bool *is_data_ready = (FAR bool *)((uintptr_t)arg);
*is_data_ready = ads1242_is_data_ready(priv);
}
break;
/* Perform a system offset calibration - Note: Zero input signal must
* be applied.
*/
case ANIOC_ADS2142_DO_SYSTEM_OFFSET_CALIB:
{
ads1242_performSystemOffsetCalibration(priv);
}
break;
/* Command was not recognized */
default:
dbg ("Unrecognized cmd: %d\n", cmd);
ret = -ENOTTY;
break;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: ads1242_register
*
* Description:
* Register the ADS1242 character device as 'devpath'
*
* Input Parameters:
* devpath - The full path to the driver to register. E.g., "/dev/ads1242"
* spi - An instance of the SPI interface to use to communicate with ADS1242
* osc_freq_hz - The frequency of the ADS1242 oscillator in Hz. Required for
* calculating the minimum delay periods when accessing the device via SPI.
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
int ads1242_register(FAR const char *devpath, FAR struct spi_dev_s *spi,
uint32_t const osc_freq_hz)
{
FAR struct ads1242_dev_s *priv;
int ret;
/* Sanity check */
DEBUGASSERT(spi != NULL);
/* Initialize the ADS1242 device structure */
priv = (FAR struct ads1242_dev_s *)kmm_malloc(sizeof(struct ads1242_dev_s));
if (priv == NULL)
{
dbg ("Failed to allocate instance\n");
return -ENOMEM;
}
priv->spi = spi;
float const osc_period_us = (1000.0 * 1000.0) / ((float)(osc_freq_hz));
priv->osc_period_us = (uint32_t)(osc_period_us);
/* Register the character driver */
ret = register_driver(devpath, &g_ads1242_fops, 0666, priv);
if (ret < 0)
{
dbg ("Failed to register driver: %d\n", ret);
kmm_free(priv);
}
/* setup SPI frequency */
SPI_SETFREQUENCY(spi, ADS1242_SPI_FREQUENCY);
/* Setup SPI mode */
SPI_SETMODE(spi, ADS1242_SPI_MODE);
return ret;
}
#endif /* CONFIG_SPI && CONFIG_ADC_ADS1242 */
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