RIOT/drivers/adt7310/adt7310.c

/*
 * Copyright (C) 2015 Eistec AB
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 *
 */
/**
 * @ingroup     drivers_adt7310
 * @{
 *
 * @file
 * @brief       Driver for the ADT7310 ±0.5°C Accurate, 16-Bit Digital SPI
 *              Temperature Sensor from Analog Devices
 *
 * @author      Joakim Nohlgård <joakim.nohlgard@eistec.se>
 *
 * @}
 */
#include <stdint.h>
#include <stdbool.h>
#include <math.h>
#include "adt7310.h"
#include "byteorder.h"
#define ENABLE_DEBUG    (0)
#include "debug.h"
/* SPI command byte parameters */
#define ADT7310_CMD_READ       (0x40)
#define ADT7310_CMD_WRITE      (0x00)
#define ADT7310_CMD_ADDR_SHIFT (3)
#define ADT7310_CMD_CONTINUOUS (0x04)
/* ****************** *
 * Register addresses *
 * ****************** */
#define ADT7310_REG_STATUS (0x00)
#define ADT7310_REG_CONFIG (0x01)
#define ADT7310_REG_VALUE  (0x02)
#define ADT7310_REG_ID     (0x03)
#define ADT7310_REG_TCRIT  (0x04)
#define ADT7310_REG_THYST  (0x05)
#define ADT7310_REG_THIGH  (0x06)
#define ADT7310_REG_TLOW   (0x07)
/* ************** *
 * Register sizes *
 * ************** */
#define ADT7310_REG_SIZE_STATUS (1)
#define ADT7310_REG_SIZE_CONFIG (1)
#define ADT7310_REG_SIZE_VALUE  (2)
#define ADT7310_REG_SIZE_ID     (1)
#define ADT7310_REG_SIZE_TCRIT  (2)
#define ADT7310_REG_SIZE_THYST  (1)
#define ADT7310_REG_SIZE_THIGH  (2)
#define ADT7310_REG_SIZE_TLOW   (2)
/* Register bit masks */
/** @brief Manufacturer ID */
#define ADT7310_REG_ID_MASK_MANUFACTURER_ID  (0xF8)
/** @brief Silicon version */
#define ADT7310_REG_ID_MASK_SILICON_VERSION  (0x07)
/** @brief Expected manufacturer ID */
#define ADT7310_EXPECTED_MANUF_ID (0b11000000)
/** @brief 13 bit temperature mask */
#define ADT7310_REG_VALUE_MASK_13BIT  (0xF8)
/** @brief Number of fractional bits in the raw readings */
#define ADT7310_VALUE_FRAC_BITS (7)
/** @brief Scale factor for converting raw temperature readings to degrees
 * Celsius, floating point number */
#define ADT7310_TEMPERATURE_LSB_FLOAT (1.f/((float)((int)1 << ADT7310_VALUE_FRAC_BITS)))
/**
 * @brief Read a register from the sensor
 *
 * @param[in]  dev    device descriptor
 * @param[in]  addr   register address
 * @param[in]  len    register size
 * @param[out] buf    destination buffer
 *
 * @return            0 on success
 * @return            -1 on communication errors
 */
static int adt7310_read_reg(const adt7310_t *dev, const uint8_t addr, const uint8_t len,
                            uint8_t *buf)
{
    int status = 0;
    uint8_t command = ADT7310_CMD_READ | (addr << ADT7310_CMD_ADDR_SHIFT);
    /* Acquire exclusive access to the bus. */
    spi_acquire(dev->spi, dev->cs, SPI_MODE_0, dev->clk);
    /* Perform the transaction */
    spi_transfer_regs(dev->spi, dev->cs, command, NULL, buf, (size_t)len);
    /* Release the bus for other threads. */
    spi_release(dev->spi);
    return status;
}
/**
 * @brief Write a register value to the sensor
 *
 * @param[in]  dev    device descriptor
 * @param[in]  addr   register address
 * @param[in]  len    register size
 * @param[in]  buf    source buffer
 *
 * @return            0 on success
 * @return            -1 on communication errors
 */
static int adt7310_write_reg(const adt7310_t *dev, const uint8_t addr,
                             const uint8_t len, uint8_t *buf)
{
    int status = 0;
    uint8_t command = ADT7310_CMD_WRITE | (addr << ADT7310_CMD_ADDR_SHIFT);
    /* Acquire exclusive access to the bus. */
    spi_acquire(dev->spi, dev->cs, SPI_MODE_0, dev->clk);
    /* Perform the transaction */
    spi_transfer_regs(dev->spi, dev->cs, command, buf, NULL, (size_t)len);
    /* Release the bus for other threads. */
    spi_release(dev->spi);
    return status;
}
int adt7310_init(adt7310_t *dev, spi_t spi, spi_clk_t clk, gpio_t cs)
{
    int status;
    uint8_t reg = 0;
    /* write device descriptor */
    dev->spi = spi;
    dev->clk = clk;
    dev->cs = cs;
    dev->initialized = false;
    dev->high_res = false;
    /* CS */
    spi_init_cs(dev->spi, dev->cs);
#if ENABLE_DEBUG
    for (int i = 0; i < 8; ++i) {
        uint16_t dbg_reg = 0;
        status = adt7310_read_reg(dev, i, sizeof(dbg_reg), (uint8_t *)&dbg_reg);
        if (status != 0) {
            printf("Error reading address 0x%02x", i);
        }
        dbg_reg = htons(dbg_reg);
        printf("%02x: %04" PRIx16 "\n", i, dbg_reg);
    }
#endif
    /* Read ID register from device */
    status = adt7310_read_reg(dev, ADT7310_REG_ID, ADT7310_REG_SIZE_ID, &reg);
    if (status != 0) {
        /* SPI bus error */
        return -1;
    }
    if ((reg & ADT7310_REG_ID_MASK_MANUFACTURER_ID) != ADT7310_EXPECTED_MANUF_ID) {
        /* Wrong part ID */
        return -2;
    }
    /* Set a configuration, go to shut down mode to save power until the sensor is needed. */
    if (adt7310_set_config(dev, ADT7310_MODE_SHUTDOWN) != 0) {
        /* communication error */
        return -3;
    }
    dev->initialized = true;
    return 0;
}
int adt7310_set_config(adt7310_t *dev, uint8_t config)
{
    if (config & ADT7310_CONF_RESOLUTION_MASK) {
        dev->high_res = true;
    }
    return adt7310_write_reg(dev, ADT7310_REG_CONFIG, ADT7310_REG_SIZE_CONFIG, &config);
}
int16_t adt7310_read_raw(const adt7310_t *dev)
{
    int status;
    int16_t raw;
    /* Read the temperature value register */
    status = adt7310_read_reg(dev, ADT7310_REG_VALUE, ADT7310_REG_SIZE_VALUE, (uint8_t*)&raw);
    if (status < 0) {
        /* communication error */
        return INT16_MIN;
    }
    /* The temperature value is sent big endian (network byte order) */
    raw = (int16_t)ntohs((uint16_t)raw);
    return raw;
}
int32_t adt7310_read(const adt7310_t *dev)
{
    int16_t raw = adt7310_read_raw(dev);
    if (raw == INT16_MIN) {
        return INT32_MIN;
    }
    if (!dev->high_res) {
        /* filter out the flag bits */
        raw &= ADT7310_REG_VALUE_MASK_13BIT;
    }
    return ((((int32_t)raw) * 1000) >> ADT7310_VALUE_FRAC_BITS);
}
float adt7310_read_float(const adt7310_t *dev)
{
    int16_t raw = adt7310_read_raw(dev);
    if (raw == INT16_MIN) {
        /* ignore cppcheck: we want to create a NaN here */
        /* cppcheck-suppress duplicateExpression */
        return (0.0f / 0.0f); /* return NaN */
    }
    if (!dev->high_res) {
        /* filter out the flag bits */
        raw &= ADT7310_REG_VALUE_MASK_13BIT;
    }
    return (((float) raw) * ADT7310_TEMPERATURE_LSB_FLOAT);
}