/* Soil Sensor Firmware
 * Ambient Temperature, Humidity, and Soil Temperature
 * Sensiplicity Systems
 * 
 *  Copyright 2015
 * 
 *  Department of Botany and Plant Pathology
 *  Center for Genome Research and Biocomputing
 *  Oregon State University
 *  Corvallis, OR 97331
 * 
 * This program is not free software; you can not redistribute it and/or
 * modify it at all.
 * 
 * This program 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. */

/* This module reads ambient humidity/temperature from the
 * SI700X and soil temperature from the TMP108. Both communicate
 * over the I2C bus. */

/* Initialize the I2C bus. */
void init_i2c(void);

/* Read the soil temperature using the old sensor present on
 * PCB revisions 1 and 2.
 * The return value is the soil temperature, in 1/16 degrees C.
 * If an error occurs, -273.125C (-4370) will be returned. */
int16_t get_soil_temp_old(void);


/* Read the soil temperature in a zone.
 * The return value is the soil temperature, in 1/16 degrees C.
 * If an error occurs, -273.125C (-4370) will be returned. */
int16_t get_soil_temp(uint8_t zone);

/* Tell the Si7006 to measure the ambient humidity and temperature.
 * This process takes about 12ms.
 * Returns 0 on success, -1 on error. */
int8_t measure_humidity(void);

/* Read the ambient temperature and humidity. measure_humidity() must be called
 * before this function.
 * humidity is the ambient relative humidity. 0=0%RH, 4095=100%RH.
 * temperature is the ambient temperature, in 1/16 degrees C.
 * If 0 is returned, the data was read successfully. Otherwise, -1 is returned.
 * This may occur if not enough time has elapsed since calling measure_humidity(). */
int8_t read_humidity(uint16_t *humidity, int16_t *temperature);