Lieven Hollevoet / Si7005

Interface to a Silicon Labs Si7005 relative humidity sensor.

Dependents:   Si7005_example

Si7005.h@0:6fbf67893ca2, 2013-04-10 (annotated)

Committer:
LievenHollevoet
Date:
Wed Apr 10 08:43:56 2013 +0000
Revision:
0:6fbf67893ca2
First working version of a library to interface to a Silicon Labs Si7005 relative humidity sensor.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
LievenHollevoet 0:6fbf67893ca2 1 /* mbed Si7005 relative humidity sensor Library
LievenHollevoet 0:6fbf67893ca2 2 *
LievenHollevoet 0:6fbf67893ca2 3 * Copyright (c) 2013, Lieven Hollevoet (http://likatronix.be)
LievenHollevoet 0:6fbf67893ca2 4 *
LievenHollevoet 0:6fbf67893ca2 5 * Permission is hereby granted, free of charge, to any person obtaining a copy
LievenHollevoet 0:6fbf67893ca2 6 * of this software and associated documentation files (the "Software"), to deal
LievenHollevoet 0:6fbf67893ca2 7 * in the Software without restriction, including without limitation the rights
LievenHollevoet 0:6fbf67893ca2 8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
LievenHollevoet 0:6fbf67893ca2 9 * copies of the Software, and to permit persons to whom the Software is
LievenHollevoet 0:6fbf67893ca2 10 * furnished to do so, subject to the following conditions:
LievenHollevoet 0:6fbf67893ca2 11 *
LievenHollevoet 0:6fbf67893ca2 12 * The above copyright notice and this permission notice shall be included in
LievenHollevoet 0:6fbf67893ca2 13 * all copies or substantial portions of the Software.
LievenHollevoet 0:6fbf67893ca2 14 *
LievenHollevoet 0:6fbf67893ca2 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
LievenHollevoet 0:6fbf67893ca2 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
LievenHollevoet 0:6fbf67893ca2 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
LievenHollevoet 0:6fbf67893ca2 18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LievenHollevoet 0:6fbf67893ca2 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
LievenHollevoet 0:6fbf67893ca2 20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
LievenHollevoet 0:6fbf67893ca2 21 * THE SOFTWARE.
LievenHollevoet 0:6fbf67893ca2 22 */
LievenHollevoet 0:6fbf67893ca2 23
LievenHollevoet 0:6fbf67893ca2 24 #ifndef SI7005_H
LievenHollevoet 0:6fbf67893ca2 25 #define SI7005_H
LievenHollevoet 0:6fbf67893ca2 26
LievenHollevoet 0:6fbf67893ca2 27 #include "mbed.h"
LievenHollevoet 0:6fbf67893ca2 28
LievenHollevoet 0:6fbf67893ca2 29 /*
LievenHollevoet 0:6fbf67893ca2 30 * register names
LievenHollevoet 0:6fbf67893ca2 31 */
LievenHollevoet 0:6fbf67893ca2 32
LievenHollevoet 0:6fbf67893ca2 33 #define SI7005_REG_STATUS 0
LievenHollevoet 0:6fbf67893ca2 34 #define SI7005_REG_DATAH 1
LievenHollevoet 0:6fbf67893ca2 35 #define SI7005_REG_DATAL 2
LievenHollevoet 0:6fbf67893ca2 36 #define SI7005_REG_CONFIG 3
LievenHollevoet 0:6fbf67893ca2 37 #define SI7005_REG_ID 17
LievenHollevoet 0:6fbf67893ca2 38
LievenHollevoet 0:6fbf67893ca2 39 /*
LievenHollevoet 0:6fbf67893ca2 40 * measurement types
LievenHollevoet 0:6fbf67893ca2 41 */
LievenHollevoet 0:6fbf67893ca2 42
LievenHollevoet 0:6fbf67893ca2 43 #define SI7005_RH 0
LievenHollevoet 0:6fbf67893ca2 44 #define SI7005_T 1
LievenHollevoet 0:6fbf67893ca2 45
LievenHollevoet 0:6fbf67893ca2 46 /** Class to interface to a Silicon Labs Si7005 relative humidity sensor.
LievenHollevoet 0:6fbf67893ca2 47 *
LievenHollevoet 0:6fbf67893ca2 48 * Example:
LievenHollevoet 0:6fbf67893ca2 49 * @code
LievenHollevoet 0:6fbf67893ca2 50 * #include "mbed.h"
LievenHollevoet 0:6fbf67893ca2 51 * #include "Si7005.h"
LievenHollevoet 0:6fbf67893ca2 52 *
LievenHollevoet 0:6fbf67893ca2 53 * Si7005 rh(p28, p27); // sda, scl
LievenHollevoet 0:6fbf67893ca2 54 * DigitalOut rh_cs_n(p26); // Chip select signal
LievenHollevoet 0:6fbf67893ca2 55 * Serial uart(USBTX, USBRX); // tx, rx
LievenHollevoet 0:6fbf67893ca2 56
LievenHollevoet 0:6fbf67893ca2 57 * int main() {
LievenHollevoet 0:6fbf67893ca2 58 *
LievenHollevoet 0:6fbf67893ca2 59 * // Enable RH sensor
LievenHollevoet 0:6fbf67893ca2 60 * rh_cs_n = 0;
LievenHollevoet 0:6fbf67893ca2 61 * // Let it startup!
LievenHollevoet 0:6fbf67893ca2 62 * wait(0.05);
LievenHollevoet 0:6fbf67893ca2 63 *
LievenHollevoet 0:6fbf67893ca2 64 * char id;
LievenHollevoet 0:6fbf67893ca2 65 * id = rh.readID();
LievenHollevoet 0:6fbf67893ca2 66 * uart.printf("Sensor type: %02X\n", id);
LievenHollevoet 0:6fbf67893ca2 67
LievenHollevoet 0:6fbf67893ca2 68 * // Relative humidity measurement
LievenHollevoet 0:6fbf67893ca2 69 * rh.startMeasurement(SI7005_RH);
LievenHollevoet 0:6fbf67893ca2 70 * while (!rh.conversionDone()) {
LievenHollevoet 0:6fbf67893ca2 71 * wait(0.01);
LievenHollevoet 0:6fbf67893ca2 72 * }
LievenHollevoet 0:6fbf67893ca2 73 * int measurement = rh.readResult(SI7005_RH);
LievenHollevoet 0:6fbf67893ca2 74 * uart.printf("RH = %i procent\n", measurement);
LievenHollevoet 0:6fbf67893ca2 75 *
LievenHollevoet 0:6fbf67893ca2 76 * // Start temperature measurement
LievenHollevoet 0:6fbf67893ca2 77 * rh.startMeasurement(SI7005_T);
LievenHollevoet 0:6fbf67893ca2 78 * while (!rh.conversionDone()){
LievenHollevoet 0:6fbf67893ca2 79 * wait (0.01);
LievenHollevoet 0:6fbf67893ca2 80 * }
LievenHollevoet 0:6fbf67893ca2 81 * measurement = rh.readResult(SI7005_T);
LievenHollevoet 0:6fbf67893ca2 82 * uart.printf("Temp = %i degrees C\n", measurement);
LievenHollevoet 0:6fbf67893ca2 83 *
LievenHollevoet 0:6fbf67893ca2 84 * // Disable the sensor
LievenHollevoet 0:6fbf67893ca2 85 * rh_cs_n = 1;
LievenHollevoet 0:6fbf67893ca2 86 *
LievenHollevoet 0:6fbf67893ca2 87 * }
LievenHollevoet 0:6fbf67893ca2 88 * @endcode
LievenHollevoet 0:6fbf67893ca2 89 */
LievenHollevoet 0:6fbf67893ca2 90 class Si7005 {
LievenHollevoet 0:6fbf67893ca2 91
LievenHollevoet 0:6fbf67893ca2 92 public:
LievenHollevoet 0:6fbf67893ca2 93
LievenHollevoet 0:6fbf67893ca2 94 /** Creates the sensor interface instance
LievenHollevoet 0:6fbf67893ca2 95 * @param sda I2C data pin
LievenHollevoet 0:6fbf67893ca2 96 * @param scl I2C clock pin
LievenHollevoet 0:6fbf67893ca2 97 */
LievenHollevoet 0:6fbf67893ca2 98 Si7005(PinName sda, PinName scl);
LievenHollevoet 0:6fbf67893ca2 99
LievenHollevoet 0:6fbf67893ca2 100 /** Read the chip ID
LievenHollevoet 0:6fbf67893ca2 101 * @returns The chip ID register contents. Should be in the format 0x5y for a Si7005 sensor where 'y' is the chip revision.
LievenHollevoet 0:6fbf67893ca2 102 */
LievenHollevoet 0:6fbf67893ca2 103 int readID (void);
LievenHollevoet 0:6fbf67893ca2 104
LievenHollevoet 0:6fbf67893ca2 105 /** Start a measurement for relative humidity or temperature
LievenHollevoet 0:6fbf67893ca2 106 * Initiate a measurement. The type can be either SI7005_RH for a relative humidity measurement or SI7005_T for a temperature measurement.
LievenHollevoet 0:6fbf67893ca2 107 * This function starts the conversion in the sensor. Before reading out the
LievenHollevoet 0:6fbf67893ca2 108 * result, ensure the conversion is done by calling conversionDone().
LievenHollevoet 0:6fbf67893ca2 109 * @param type Either SI7005_RH for humidity measurement or SI7005_T for temperature
LievenHollevoet 0:6fbf67893ca2 110 */
LievenHollevoet 0:6fbf67893ca2 111 void startMeasurement (char type);
LievenHollevoet 0:6fbf67893ca2 112
LievenHollevoet 0:6fbf67893ca2 113 /** Checks if the measurement is done.
LievenHollevoet 0:6fbf67893ca2 114 * Reports true if the conversion is finished. This is detected by reading the DONE bit in the STATUS register of the sensor.
LievenHollevoet 0:6fbf67893ca2 115 * @returns true if the conversion is done
LievenHollevoet 0:6fbf67893ca2 116 */
LievenHollevoet 0:6fbf67893ca2 117 bool conversionDone (void);
LievenHollevoet 0:6fbf67893ca2 118
LievenHollevoet 0:6fbf67893ca2 119 /** Reads the measurement result.
LievenHollevoet 0:6fbf67893ca2 120 * @param type Either SI7005_RH for humidity measurement or SI7005_T for temperature
LievenHollevoet 0:6fbf67893ca2 121 * @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.
LievenHollevoet 0:6fbf67893ca2 122 */
LievenHollevoet 0:6fbf67893ca2 123 int readResult (char type);
LievenHollevoet 0:6fbf67893ca2 124
LievenHollevoet 0:6fbf67893ca2 125 protected:
LievenHollevoet 0:6fbf67893ca2 126
LievenHollevoet 0:6fbf67893ca2 127 void _write(int reg, int data);
LievenHollevoet 0:6fbf67893ca2 128 int _read(int reg);
LievenHollevoet 0:6fbf67893ca2 129 int _read_int(int reg);
LievenHollevoet 0:6fbf67893ca2 130 int _addr;
LievenHollevoet 0:6fbf67893ca2 131 I2C _i2c;
LievenHollevoet 0:6fbf67893ca2 132
LievenHollevoet 0:6fbf67893ca2 133 };
LievenHollevoet 0:6fbf67893ca2 134
LievenHollevoet 0:6fbf67893ca2 135
LievenHollevoet 0:6fbf67893ca2 136 #endif
LievenHollevoet 0:6fbf67893ca2 137