1 /*
2 * Author: William Penner <william.penner@intel.com>
3 * Copyright (c) 2014 Intel Corporation.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a copy
6 * of this software and associated documentation files (the "Software"), to deal
7 * in the Software without restriction, including without limitation the rights
8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 * copies of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be included in
13 * all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21 * THE SOFTWARE.
22 */
23
24 #include <iostream>
25 #include <string>
26 #include <stdexcept>
27
28 #include <unistd.h>
29 #include <stdlib.h>
30
31 #include "htu21d.h"
32
33 using namespace upm;
34
HTU21D(int bus,int devAddr)35 HTU21D::HTU21D(int bus, int devAddr) : m_i2ControlCtx(bus) {
36 m_temperature = 0;
37 m_humidity = 0;
38
39 m_name = HTU21D_NAME;
40
41 m_controlAddr = devAddr;
42 m_bus = bus;
43
44 mraa::Result ret = m_i2ControlCtx.address(m_controlAddr);
45 if (ret != mraa::SUCCESS) {
46 throw std::invalid_argument(std::string(__FUNCTION__) +
47 ": mraa_i2c_address() failed");
48 }
49 resetSensor();
50 }
51
52 void
resetSensor(void)53 HTU21D::resetSensor(void)
54 {
55 uint8_t data;
56 m_i2ControlCtx.address (m_controlAddr);
57 m_i2ControlCtx.write (&data, 1);
58 usleep(20000);
59 }
60
61 /*
62 * Convert register value to degC * 1000
63 */
64 int32_t
convertTemp(int32_t regval)65 HTU21D::convertTemp(int32_t regval)
66 {
67 return ((21965 * (regval & 0xFFFC)) >> 13) - 46850;
68 }
69
70 /*
71 * Convert register value to %RH * 1000
72 */
73 int32_t
convertRH(int regval)74 HTU21D::convertRH(int regval)
75 {
76 return ((15625 * (regval & 0xFFFC)) >> 13) - 6000;
77 }
78
79 int
sampleData(void)80 HTU21D::sampleData(void)
81 {
82 uint32_t itemp;
83
84 itemp = i2cReadReg_16(HTU21D_READ_TEMP_HOLD);
85 m_temperature = convertTemp(itemp);
86
87 itemp = i2cReadReg_16(HTU21D_READ_HUMIDITY_HOLD);
88 m_humidity = convertRH(itemp);
89
90 return 0;
91 }
92
93 float
getTemperature(int bSampleData)94 HTU21D::getTemperature(int bSampleData)
95 {
96 if (bSampleData) {
97 sampleData();
98 }
99 return (float)m_temperature / 1000;
100 }
101
102 float
getHumidity(int bSampleData)103 HTU21D::getHumidity(int bSampleData)
104 {
105 if (bSampleData) {
106 sampleData();
107 }
108 return (float)m_humidity / 1000;
109 }
110
111 /*
112 * Use the compensation equation from the datasheet to correct the
113 * current reading
114 * RHcomp = RHactualT + (25 - Tactual) * CoeffTemp
115 * RHcomp is in units of %RH * 1000
116 */
117 float
getCompRH(int bSampleData)118 HTU21D::getCompRH(int bSampleData)
119 {
120 if (bSampleData) {
121 sampleData();
122 }
123 return (float)(m_humidity + (25000 - m_temperature) * 3 / 20) / 1000;
124 }
125
126 int
setHeater(int bEnable)127 HTU21D::setHeater(int bEnable)
128 {
129 uint8_t userreg;
130
131 userreg = i2cReadReg_8(HTU21D_READ_USER_REG);
132 if (bEnable)
133 userreg |= HTU21D_HEATER_ENABLE;
134 else
135 userreg &= ~HTU21D_HEATER_ENABLE;
136 if (i2cWriteReg(HTU21D_WRITE_USER_REG, userreg) < 0)
137 return -1;
138
139 return 0;
140 }
141
142 /*
143 * Test function: when reading the HTU21D many times rapidly should
144 * result in a temperature increase. This test will verify that the
145 * value is changing from read to read
146 */
147
148 int
testSensor(void)149 HTU21D::testSensor(void)
150 {
151 int i;
152 int iError = 0;
153 float fTemp, fHum;
154 float fTempMax, fTempMin;
155 float fHumMax, fHumMin;
156 float fHumFirst, fTempFirst;
157
158 fprintf(stdout, "Executing Sensor Test\n" );
159
160 fHum = getHumidity(true);
161 fTemp = getTemperature(false);
162 fTempFirst = fTempMax = fTempMin = fTemp;
163 fHumFirst = fHumMax = fHumMin = fHum;
164
165 // Turn on the heater to make a sensor change
166 setHeater(true);
167
168 // Then sample the sensor a few times
169 for (i=0; i < 10; i++) {
170 fHum = getHumidity(true);
171 fTemp = getTemperature(false);
172 if (fHum < fHumMin) fHumMin = fHum;
173 if (fHum > fHumMax) fHumMax = fHum;
174 if (fTemp < fTempMin) fTempMin = fTemp;
175 if (fTemp > fTempMax) fTempMax = fTemp;
176 usleep(50000);
177 }
178
179 // Turn off the heater
180 setHeater(false);
181
182 // Now check the results
183 if ((fTemp - fTempFirst) <= 0) {
184 fprintf(stdout, " Temperature should have increased, but didn't\n" );
185 iError++;
186 }
187 if (fHumMin == fHumMax) {
188 fprintf(stdout, " Humidity reading was unchanged - warning\n" );
189 iError++;
190 }
191 if (fTempMin == fTempMax) {
192 fprintf(stdout, " Temperature reading was unchanged - warning\n" );
193 iError++;
194 }
195 if (iError == 0) {
196 fprintf(stdout, " Device appears functional\n" );
197 }
198
199 fprintf(stdout, " Test complete\n" );
200
201 return iError;
202 }
203
204 /*
205 * Functions to read and write data to the i2c device
206 */
207
208 mraa::Result
i2cWriteReg(uint8_t reg,uint8_t value)209 HTU21D::i2cWriteReg (uint8_t reg, uint8_t value) {
210 mraa::Result error = mraa::SUCCESS;
211
212 uint8_t data[2] = { reg, value };
213 m_i2ControlCtx.address (m_controlAddr);
214 error = m_i2ControlCtx.write (data, 2);
215 if ( error != mraa::SUCCESS)
216 throw std::invalid_argument(std::string(__FUNCTION__) +
217 ": mraa_i2c_write() failed");
218
219 return error;
220 }
221
222 uint16_t
i2cReadReg_16(int reg)223 HTU21D::i2cReadReg_16 (int reg) {
224 uint16_t data;
225 m_i2ControlCtx.address(m_controlAddr);
226 data = (uint16_t)m_i2ControlCtx.readReg(reg) << 8;
227 data |= (uint16_t)m_i2ControlCtx.readReg(reg+1);
228 return data;
229 }
230
231 uint8_t
i2cReadReg_8(int reg)232 HTU21D::i2cReadReg_8 (int reg) {
233 m_i2ControlCtx.address(m_controlAddr);
234 return m_i2ControlCtx.readReg(reg);
235 }
236
237