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
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
|
/*
* 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.
*/
#include <iostream>
#include <string>
#include <stdexcept>
#include <unistd.h>
#include <stdlib.h>
#include "htu21d.hpp"
using namespace upm;
HTU21D::HTU21D(int bus, int devAddr) : m_i2ControlCtx(bus) {
m_temperature = 0;
m_humidity = 0;
m_name = HTU21D_NAME;
m_controlAddr = devAddr;
m_bus = bus;
mraa::Result ret = m_i2ControlCtx.address(m_controlAddr);
if (ret != mraa::SUCCESS) {
throw std::invalid_argument(std::string(__FUNCTION__) +
": mraa_i2c_address() failed");
}
resetSensor();
}
void
HTU21D::resetSensor(void)
{
uint8_t data;
m_i2ControlCtx.address (m_controlAddr);
m_i2ControlCtx.write (&data, 1);
usleep(20000);
}
/*
* Convert register value to degC * 1000
*/
int32_t
HTU21D::convertTemp(int32_t regval)
{
return ((21965 * (regval & 0xFFFC)) >> 13) - 46850;
}
/*
* Convert register value to %RH * 1000
*/
int32_t
HTU21D::convertRH(int regval)
{
return ((15625 * (regval & 0xFFFC)) >> 13) - 6000;
}
int
HTU21D::sampleData(void)
{
uint32_t itemp;
itemp = i2cReadReg_16(HTU21D_READ_TEMP_HOLD);
m_temperature = convertTemp(itemp);
itemp = i2cReadReg_16(HTU21D_READ_HUMIDITY_HOLD);
m_humidity = convertRH(itemp);
return 0;
}
float
HTU21D::getTemperature(int bSampleData)
{
if (bSampleData) {
sampleData();
}
return (float)m_temperature / 1000;
}
float
HTU21D::getHumidity(int bSampleData)
{
if (bSampleData) {
sampleData();
}
return (float)m_humidity / 1000;
}
/*
* Use the compensation equation from the datasheet to correct the
* current reading
* RHcomp = RHactualT + (25 - Tactual) * CoeffTemp
* RHcomp is in units of %RH * 1000
*/
float
HTU21D::getCompRH(int bSampleData)
{
if (bSampleData) {
sampleData();
}
return (float)(m_humidity + (25000 - m_temperature) * 3 / 20) / 1000;
}
int
HTU21D::setHeater(int bEnable)
{
uint8_t userreg;
userreg = i2cReadReg_8(HTU21D_READ_USER_REG);
if (bEnable)
userreg |= HTU21D_HEATER_ENABLE;
else
userreg &= ~HTU21D_HEATER_ENABLE;
if (i2cWriteReg(HTU21D_WRITE_USER_REG, userreg) < 0)
return -1;
return 0;
}
/*
* Test function: when reading the HTU21D many times rapidly should
* result in a temperature increase. This test will verify that the
* value is changing from read to read
*/
int
HTU21D::testSensor(void)
{
int i;
int iError = 0;
float fTemp, fHum;
float fTempMax, fTempMin;
float fHumMax, fHumMin;
float fHumFirst, fTempFirst;
fprintf(stdout, "Executing Sensor Test\n" );
fHum = getHumidity(true);
fTemp = getTemperature(false);
fTempFirst = fTempMax = fTempMin = fTemp;
fHumFirst = fHumMax = fHumMin = fHum;
// Turn on the heater to make a sensor change
setHeater(true);
// Then sample the sensor a few times
for (i=0; i < 10; i++) {
fHum = getHumidity(true);
fTemp = getTemperature(false);
if (fHum < fHumMin) fHumMin = fHum;
if (fHum > fHumMax) fHumMax = fHum;
if (fTemp < fTempMin) fTempMin = fTemp;
if (fTemp > fTempMax) fTempMax = fTemp;
usleep(50000);
}
// Turn off the heater
setHeater(false);
// Now check the results
if ((fTemp - fTempFirst) <= 0) {
fprintf(stdout, " Temperature should have increased, but didn't\n" );
iError++;
}
if (fHumMin == fHumMax) {
fprintf(stdout, " Humidity reading was unchanged - warning\n" );
iError++;
}
if (fTempMin == fTempMax) {
fprintf(stdout, " Temperature reading was unchanged - warning\n" );
iError++;
}
if (iError == 0) {
fprintf(stdout, " Device appears functional\n" );
}
fprintf(stdout, " Test complete\n" );
return iError;
}
/*
* Functions to read and write data to the i2c device
*/
mraa::Result
HTU21D::i2cWriteReg (uint8_t reg, uint8_t value) {
mraa::Result error = mraa::SUCCESS;
uint8_t data[2] = { reg, value };
m_i2ControlCtx.address (m_controlAddr);
error = m_i2ControlCtx.write (data, 2);
if ( error != mraa::SUCCESS)
throw std::invalid_argument(std::string(__FUNCTION__) +
": mraa_i2c_write() failed");
return error;
}
uint16_t
HTU21D::i2cReadReg_16 (int reg) {
uint16_t data;
m_i2ControlCtx.address(m_controlAddr);
data = (uint16_t)m_i2ControlCtx.readReg(reg) << 8;
data |= (uint16_t)m_i2ControlCtx.readReg(reg+1);
return data;
}
uint8_t
HTU21D::i2cReadReg_8 (int reg) {
m_i2ControlCtx.address(m_controlAddr);
return m_i2ControlCtx.readReg(reg);
}
|
