ltc2378.h

Go to the documentation of this file.

/***************************************************************************/
 
#ifndef __LTC2378_H__
#define __LTC2378_H__
 
#include <stdint.h>
#include "no_os_spi.h"
#include "no_os_gpio.h"
#include "no_os_delay.h"
#include "no_os_error.h"
 
#define LTC2378_RESOLUTION_UNIPOLAR (1 << 20) /* 2^20 = 1048576 */
#define LTC2378_RESOLUTION_BIPOLAR  (1 << 19) /* 2^19 = 524288 */
 
/* Timing constants */
#define LTC2378_BUSY_TIMEOUT_US     1000      /* Timeout for BUSY signal in microseconds */
#define LTC2378_CNV_PULSE_WIDTH_US  1         /* CNV pulse width in microseconds */
#define LTC2378_CONVERSION_DELAY_US 1         /* Conversion delay when BUSY not available */
#define LTC2378_POWERDOWN_DELAY_US  2         /* Power-down setup time in microseconds */
 
/* IIO scale calculation constants */
#define LTC2378_IIO_SCALE_UNIPOLAR_SHIFT  20  /* 2^20 for unipolar mode */
#define LTC2378_IIO_SCALE_BIPOLAR_SHIFT   19  /* 2^19 for bipolar mode */
 
/* SPI data parsing constants */
#define LTC2378_DATA_MASK             0xFFFFF  /* 20-bit data mask */
#define LTC2378_DATA_SHIFT_BYTE0      12       /* Shift for byte 0 */
#define LTC2378_DATA_SHIFT_BYTE1      4        /* Shift for byte 1 */
#define LTC2378_DATA_SHIFT_BYTE2      4        /* Right shift for byte 2 */
#define LTC2378_SIGN_BIT_POSITION     19       /* Sign bit position for bipolar mode */

enum ltc2378_input_mode {
    LTC2378_BIPOLAR,   /* Bipolar input: -Vref to +Vref */
    LTC2378_UNIPOLAR   /* Unipolar input: 0 to Vref */
};

struct ltc2378_dev {
    struct no_os_spi_desc *spi_desc;
    struct no_os_gpio_desc *gpio_cnv;
    struct no_os_gpio_desc *gpio_busy;
    uint32_t vref_uv;
    enum ltc2378_input_mode input_mode;
};

struct ltc2378_init_param {
    const struct no_os_spi_init_param *spi_init;
    const struct no_os_gpio_init_param *gpio_cnv_init;
    const struct no_os_gpio_init_param *gpio_busy_init;
    uint32_t vref_uv;
    enum ltc2378_input_mode input_mode;
};
 
/* Function declarations */
 
/* Initialize the LTC2378-20 device */
int ltc2378_init(struct ltc2378_dev **device,
         const struct ltc2378_init_param *init_param);
 
/* Remove the LTC2378-20 device and free allocated resources */
int ltc2378_remove(struct ltc2378_dev *dev);
 
/* Start a single ADC conversion */
int ltc2378_start_conversion(struct ltc2378_dev *dev);
 
/* Read a single raw ADC conversion result */
int ltc2378_read_raw(struct ltc2378_dev *dev, uint32_t *data);
 
/* Read and average multiple ADC conversion results */
int ltc2378_read_avg(struct ltc2378_dev *dev, uint32_t *avg_data,
             uint16_t samples);
 
/* Convert raw ADC value to voltage in microvolts */
int ltc2378_raw_to_uv(struct ltc2378_dev *dev, uint32_t raw,
              int32_t *voltage_uv);
 
/* Put the LTC2378-20 into power-down mode */
int ltc2378_power_down(struct ltc2378_dev *dev);
 
#endif /* __LTC2378_H__ */