1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/*
* Author: William Penner <william.penner@intel.com>
* Copyright (c) 2014 Intel Corporation.
*
* 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.
*/
#pragma once
#include <string>
#include <mraa/i2c.hpp>
#include <math.h>
#define HTU21D_NAME "htu21d"
#define HTU21D_I2C_ADDRESS 0x40
/* HTU21D Commands */
#define HTU21D_READ_TEMP_HOLD 0xE3
#define HTU21D_READ_HUMIDITY_HOLD 0xE5
#define HTU21D_WRITE_USER_REG 0xE6
#define HTU21D_READ_USER_REG 0xE7
#define HTU21D_SOFT_RESET 0xFE
/* User Register Bit Definition */
#define HTU21D_DISABLE_OTP 0x02
#define HTU21D_HEATER_ENABLE 0x04
#define HTU21D_END_OF_BATTERY 0x40
#define HTU21D_RESO_RH12_T14 0x00
#define HTU21D_RESO_RH8_T12 0x01
#define HTU21D_RESO_RH10_T13 0x80
#define HTU21D_RESO_RH11_T11 0x81
namespace upm {
/**
* @brief HTU21D Humidity Sensor library
* @defgroup htu21d libupm-htu21d
* @ingroup seeed adafruit sparkfun i2c temp
*/
/**
* @library htu21d
* @sensor htu21d
* @comname HTU21D Temperature & Humidity Sensor
* @type temp
* @man seeed adafruit sparkfun
* @web http://www.meas-spec.com/downloads/HTU21D.pdf
* @con i2c
*
* @brief API for the HTU21D Temperature & Humidity Sensor
*
* HTU21D by Measurement Specialties is a digital humidity sensor with
* temperature output.
* RH reports between 0 and 100%, and the temperature range is
* -40 to +125 degC. Note: getCompRH is the preferred
* function below (passing true to cause a measurement cycle). If
* actual values used for the compensated ready are necessary, use
* the getHumidity(false) and getTemperature(false) functions following
* the getCompRH call.
* Also note the sensor should not perform more than a couple of
* measurements per second to limit the heating of the sensor.
*
* @image html htu21d.jpeg
* @snippet htu21d.cxx Interesting
*/
class HTU21D {
public:
/**
* Instantiates an HTU21D object
*
* @param bus Number of the used bus
* @param devAddr Address of the used I2C device
* @param mode HTU21D oversampling
*/
HTU21D (int bus, int devAddr=HTU21D_I2C_ADDRESS);
/**
* Initiates a temperature/pressure mesasurement and waits for the function
* to complete. The humidity and temperature registers can be read
* after this call.
*/
int sampleData(void);
/**
* Gets the current measured humidity [RH]
*/
float getHumidity(int bSampleData = false);
/**
* Gets the humidity cell temperature [degC]
*/
float getTemperature(int bSampleData = false);
/**
* Using the current humidity and temperature, the function
* calculates the compensated RH using the equation from
* the datasheet.
*/
float getCompRH(int bSampleData = true);
/**
* Sets the heater state. The heater is used to test
* the sensor functionality since the temperature should increase
* 0.5 to 1.5 degC, and the humidity should decrease. The
* testSensor() function below uses the heater.
*
* @param bEnable Sets to non-zero to turn the heater on
*/
int setHeater(int bEnable = false);
/**
* Performs a soft reset of the MPL3115A2 device to ensure
* it is in a known state. This function can be used to reset
* the min/max temperature and pressure values.
*/
void resetSensor(void);
/**
* Tests the device and verifies it
* is operating correctly.
*
*/
int testSensor(void);
/**
* Writes to a one-byte register
*
* @param reg Address of the register
* @param value Byte to be written
*/
mraa::Result i2cWriteReg (uint8_t reg, uint8_t value);
/**
* Reads a two-byte register
*
* @param reg Address of the register
*/
uint16_t i2cReadReg_16 (int reg);
/**
* Reads a one-byte register
*
* @param reg Address of the register
*/
uint8_t i2cReadReg_8 (int reg);
private:
/**
* Converts the temperature register to degC * 1000
*/
int32_t convertTemp(int32_t regval);
/**
* Converts the RH register to %RH * 1000
*/
int32_t convertRH(int32_t regval);
std::string m_name;
int m_controlAddr;
int m_bus;
mraa::I2c m_i2ControlCtx;
int32_t m_temperature;
int32_t m_humidity;
};
}
|
