Interface to a Silicon Labs Si7005 relative humidity sensor.
Si7005.h
- Committer:
- LievenHollevoet
- Date:
- 2013-04-10
- Revision:
- 0:6fbf67893ca2
File content as of revision 0:6fbf67893ca2:
/* mbed Si7005 relative humidity sensor Library * * Copyright (c) 2013, Lieven Hollevoet (http://likatronix.be) * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #ifndef SI7005_H #define SI7005_H #include "mbed.h" /* * register names */ #define SI7005_REG_STATUS 0 #define SI7005_REG_DATAH 1 #define SI7005_REG_DATAL 2 #define SI7005_REG_CONFIG 3 #define SI7005_REG_ID 17 /* * measurement types */ #define SI7005_RH 0 #define SI7005_T 1 /** Class to interface to a Silicon Labs Si7005 relative humidity sensor. * * Example: * @code * #include "mbed.h" * #include "Si7005.h" * * Si7005 rh(p28, p27); // sda, scl * DigitalOut rh_cs_n(p26); // Chip select signal * Serial uart(USBTX, USBRX); // tx, rx * int main() { * * // Enable RH sensor * rh_cs_n = 0; * // Let it startup! * wait(0.05); * * char id; * id = rh.readID(); * uart.printf("Sensor type: %02X\n", id); * // Relative humidity measurement * rh.startMeasurement(SI7005_RH); * while (!rh.conversionDone()) { * wait(0.01); * } * int measurement = rh.readResult(SI7005_RH); * uart.printf("RH = %i procent\n", measurement); * * // Start temperature measurement * rh.startMeasurement(SI7005_T); * while (!rh.conversionDone()){ * wait (0.01); * } * measurement = rh.readResult(SI7005_T); * uart.printf("Temp = %i degrees C\n", measurement); * * // Disable the sensor * rh_cs_n = 1; * * } * @endcode */ class Si7005 { public: /** Creates the sensor interface instance * @param sda I2C data pin * @param scl I2C clock pin */ Si7005(PinName sda, PinName scl); /** Read the chip ID * @returns The chip ID register contents. Should be in the format 0x5y for a Si7005 sensor where 'y' is the chip revision. */ int readID (void); /** Start a measurement for relative humidity or temperature * Initiate a measurement. The type can be either SI7005_RH for a relative humidity measurement or SI7005_T for a temperature measurement. * This function starts the conversion in the sensor. Before reading out the * result, ensure the conversion is done by calling conversionDone(). * @param type Either SI7005_RH for humidity measurement or SI7005_T for temperature */ void startMeasurement (char type); /** Checks if the measurement is done. * Reports true if the conversion is finished. This is detected by reading the DONE bit in the STATUS register of the sensor. * @returns true if the conversion is done */ bool conversionDone (void); /** Reads the measurement result. * @param type Either SI7005_RH for humidity measurement or SI7005_T for temperature * @returns The measurement result as specified in the datasheet, a 12-bit value for the relative humidity measurement and a 14-bit value for a temperature measurement. */ int readResult (char type); protected: void _write(int reg, int data); int _read(int reg); int _read_int(int reg); int _addr; I2C _i2c; }; #endif