Device driver for Si7020 Digital humidity and temperature sensor.
Dependents: Si7020_example MAXWSNENV_sensors MAXWSNENV_sensors Hello-Uzuki-sensor-shield ... more
Si7020 Device Driver
This is a device driver for the Si7020 Humidity and temperature sensor. It uses I2C to communicate humidity and temperature data.
Si7020.cpp@1:eca9d19c17ab, 2015-04-17 (annotated)
- Committer:
- kgills
- Date:
- Fri Apr 17 11:25:00 2015 -0500
- Revision:
- 1:eca9d19c17ab
- Parent:
- 0:9a1febb56203
Fixing compiler float warnings.
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
kgills |
0:9a1febb56203 | 1 | /******************************************************************************* |
kgills |
0:9a1febb56203 | 2 | * Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved. |
kgills |
0:9a1febb56203 | 3 | * |
kgills |
0:9a1febb56203 | 4 | * Permission is hereby granted, free of charge, to any person obtaining a |
kgills |
0:9a1febb56203 | 5 | * copy of this software and associated documentation files (the "Software"), |
kgills |
0:9a1febb56203 | 6 | * to deal in the Software without restriction, including without limitation |
kgills |
0:9a1febb56203 | 7 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
kgills |
0:9a1febb56203 | 8 | * and/or sell copies of the Software, and to permit persons to whom the |
kgills |
0:9a1febb56203 | 9 | * Software is furnished to do so, subject to the following conditions: |
kgills |
0:9a1febb56203 | 10 | * |
kgills |
0:9a1febb56203 | 11 | * The above copyright notice and this permission notice shall be included |
kgills |
0:9a1febb56203 | 12 | * in all copies or substantial portions of the Software. |
kgills |
0:9a1febb56203 | 13 | * |
kgills |
0:9a1febb56203 | 14 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
kgills |
0:9a1febb56203 | 15 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
kgills |
0:9a1febb56203 | 16 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
kgills |
0:9a1febb56203 | 17 | * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES |
kgills |
0:9a1febb56203 | 18 | * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, |
kgills |
0:9a1febb56203 | 19 | * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
kgills |
0:9a1febb56203 | 20 | * OTHER DEALINGS IN THE SOFTWARE. |
kgills |
0:9a1febb56203 | 21 | * |
kgills |
0:9a1febb56203 | 22 | * Except as contained in this notice, the name of Maxim Integrated |
kgills |
0:9a1febb56203 | 23 | * Products, Inc. shall not be used except as stated in the Maxim Integrated |
kgills |
0:9a1febb56203 | 24 | * Products, Inc. Branding Policy. |
kgills |
0:9a1febb56203 | 25 | * |
kgills |
0:9a1febb56203 | 26 | * The mere transfer of this software does not imply any licenses |
kgills |
0:9a1febb56203 | 27 | * of trade secrets, proprietary technology, copyrights, patents, |
kgills |
0:9a1febb56203 | 28 | * trademarks, maskwork rights, or any other form of intellectual |
kgills |
0:9a1febb56203 | 29 | * property whatsoever. Maxim Integrated Products, Inc. retains all |
kgills |
0:9a1febb56203 | 30 | * ownership rights. |
kgills |
0:9a1febb56203 | 31 | ******************************************************************************* |
kgills |
0:9a1febb56203 | 32 | */ |
kgills |
0:9a1febb56203 | 33 | |
kgills |
0:9a1febb56203 | 34 | #include "Si7020.h" |
kgills |
0:9a1febb56203 | 35 | |
kgills |
0:9a1febb56203 | 36 | /***** Definitions *****/ |
kgills |
0:9a1febb56203 | 37 | #define I2C_ADDR (0x80) // 1000000x |
kgills |
0:9a1febb56203 | 38 | #define POLYVAL (0x131) |
kgills |
0:9a1febb56203 | 39 | |
kgills |
0:9a1febb56203 | 40 | /***** File Scope Data *****/ |
kgills |
0:9a1febb56203 | 41 | static const char cmd_meas_humid[] = { 0xE5 }; |
kgills |
0:9a1febb56203 | 42 | static const char cmd_meas_humid_no_hold[] = { 0xF5 }; |
kgills |
0:9a1febb56203 | 43 | static const char cmd_meas_temp[] = { 0xE3 }; |
kgills |
0:9a1febb56203 | 44 | static const char cmd_meas_temp_no_hold[] = { 0xF3 }; |
kgills |
0:9a1febb56203 | 45 | static const char cmd_meas_prev_temp[] = { 0xE0 }; |
kgills |
0:9a1febb56203 | 46 | static const char cmd_rst[] = { 0xFE }; |
kgills |
0:9a1febb56203 | 47 | static const char cmd_write_user1[] = { 0xE6 }; |
kgills |
0:9a1febb56203 | 48 | static const char cmd_read_user1[] = { 0xE7 }; |
kgills |
0:9a1febb56203 | 49 | static const char cmd_id_1[] = { 0xFA, 0x0F }; |
kgills |
0:9a1febb56203 | 50 | static const char cmd_id_2[] = { 0xFC, 0xC9 }; |
kgills |
0:9a1febb56203 | 51 | static const char cmd_fw_ver[] = { 0x84, 0xB8 }; |
kgills |
0:9a1febb56203 | 52 | |
kgills |
0:9a1febb56203 | 53 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 54 | Si7020::Si7020(PinName sda, PinName scl) |
kgills |
0:9a1febb56203 | 55 | { |
kgills |
0:9a1febb56203 | 56 | i2c_ = new I2C(sda, scl); |
kgills |
0:9a1febb56203 | 57 | i2c_owner = true; |
kgills |
0:9a1febb56203 | 58 | |
kgills |
0:9a1febb56203 | 59 | // 400KHz, as specified by the datasheet. |
kgills |
0:9a1febb56203 | 60 | i2c_->frequency(400000); |
kgills |
0:9a1febb56203 | 61 | } |
kgills |
0:9a1febb56203 | 62 | |
kgills |
0:9a1febb56203 | 63 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 64 | Si7020::Si7020(I2C *i2c) : |
kgills |
0:9a1febb56203 | 65 | i2c_(i2c) |
kgills |
0:9a1febb56203 | 66 | { |
kgills |
0:9a1febb56203 | 67 | i2c_owner = false; |
kgills |
0:9a1febb56203 | 68 | } |
kgills |
0:9a1febb56203 | 69 | |
kgills |
0:9a1febb56203 | 70 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 71 | Si7020::~Si7020() |
kgills |
0:9a1febb56203 | 72 | { |
kgills |
0:9a1febb56203 | 73 | if(i2c_owner) { |
kgills |
0:9a1febb56203 | 74 | delete i2c_; |
kgills |
0:9a1febb56203 | 75 | } |
kgills |
0:9a1febb56203 | 76 | } |
kgills |
0:9a1febb56203 | 77 | |
kgills |
0:9a1febb56203 | 78 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 79 | int Si7020::reset(void) |
kgills |
0:9a1febb56203 | 80 | { |
kgills |
0:9a1febb56203 | 81 | if (i2c_->write(I2C_ADDR, cmd_rst, sizeof(cmd_rst)) != 0) { |
kgills |
0:9a1febb56203 | 82 | return -1; |
kgills |
0:9a1febb56203 | 83 | } |
kgills |
0:9a1febb56203 | 84 | |
kgills |
0:9a1febb56203 | 85 | return 0; |
kgills |
0:9a1febb56203 | 86 | } |
kgills |
0:9a1febb56203 | 87 | |
kgills |
0:9a1febb56203 | 88 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 89 | int Si7020::getElectronicId(char* id) |
kgills |
0:9a1febb56203 | 90 | { |
kgills |
0:9a1febb56203 | 91 | // Send cmd with repeated start |
kgills |
0:9a1febb56203 | 92 | if (i2c_->write(I2C_ADDR, cmd_id_1, sizeof(cmd_id_1), true) != 0) { |
kgills |
0:9a1febb56203 | 93 | return -1; |
kgills |
0:9a1febb56203 | 94 | } |
kgills |
0:9a1febb56203 | 95 | |
kgills |
0:9a1febb56203 | 96 | // Read first portion of ID |
kgills |
0:9a1febb56203 | 97 | char temp[8]; |
kgills |
0:9a1febb56203 | 98 | if (i2c_->read(I2C_ADDR, temp, 8, false) != 0) { |
kgills |
0:9a1febb56203 | 99 | return -1; |
kgills |
0:9a1febb56203 | 100 | } |
kgills |
0:9a1febb56203 | 101 | |
kgills |
0:9a1febb56203 | 102 | // Check the CRC |
kgills |
0:9a1febb56203 | 103 | char crc = 0; |
kgills |
0:9a1febb56203 | 104 | int i; |
kgills |
0:9a1febb56203 | 105 | for(i = 0; i < 4; i++) { |
kgills |
0:9a1febb56203 | 106 | crc = crc8(temp[2*i], crc); |
kgills |
0:9a1febb56203 | 107 | if(crc != temp[2*i +1]) { |
kgills |
0:9a1febb56203 | 108 | return -1; |
kgills |
0:9a1febb56203 | 109 | } |
kgills |
0:9a1febb56203 | 110 | } |
kgills |
0:9a1febb56203 | 111 | |
kgills |
0:9a1febb56203 | 112 | // Save top portion of ID |
kgills |
0:9a1febb56203 | 113 | id[7] = temp [0]; |
kgills |
0:9a1febb56203 | 114 | id[6] = temp [2]; |
kgills |
0:9a1febb56203 | 115 | id[5] = temp [4]; |
kgills |
0:9a1febb56203 | 116 | id[4] = temp [6]; |
kgills |
0:9a1febb56203 | 117 | |
kgills |
0:9a1febb56203 | 118 | // Send cmd with repeated start |
kgills |
0:9a1febb56203 | 119 | if (i2c_->write(I2C_ADDR, cmd_id_2, sizeof(cmd_id_2), true) != 0) { |
kgills |
0:9a1febb56203 | 120 | return -1; |
kgills |
0:9a1febb56203 | 121 | } |
kgills |
0:9a1febb56203 | 122 | |
kgills |
0:9a1febb56203 | 123 | // Read rest of ID |
kgills |
0:9a1febb56203 | 124 | if (i2c_->read(I2C_ADDR, temp, 6, false) != 0) { |
kgills |
0:9a1febb56203 | 125 | return -1; |
kgills |
0:9a1febb56203 | 126 | } |
kgills |
0:9a1febb56203 | 127 | |
kgills |
0:9a1febb56203 | 128 | // Check the CRC |
kgills |
0:9a1febb56203 | 129 | crc = 0; |
kgills |
0:9a1febb56203 | 130 | for(i = 0; i < 2; i++) { |
kgills |
0:9a1febb56203 | 131 | crc = crc8(temp[3*i], crc); |
kgills |
0:9a1febb56203 | 132 | crc = crc8(temp[3*i + 1], crc); |
kgills |
0:9a1febb56203 | 133 | if(crc != temp[3*i + 2]) { |
kgills |
0:9a1febb56203 | 134 | return -1; |
kgills |
0:9a1febb56203 | 135 | } |
kgills |
0:9a1febb56203 | 136 | } |
kgills |
0:9a1febb56203 | 137 | |
kgills |
0:9a1febb56203 | 138 | // Save bottom portion of ID |
kgills |
0:9a1febb56203 | 139 | id[3] = temp [0]; |
kgills |
0:9a1febb56203 | 140 | id[2] = temp [1]; |
kgills |
0:9a1febb56203 | 141 | id[1] = temp [3]; |
kgills |
0:9a1febb56203 | 142 | id[0] = temp [4]; |
kgills |
0:9a1febb56203 | 143 | |
kgills |
0:9a1febb56203 | 144 | return 0; |
kgills |
0:9a1febb56203 | 145 | } |
kgills |
0:9a1febb56203 | 146 | |
kgills |
0:9a1febb56203 | 147 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 148 | int Si7020::configResolution(Si7020::resolution_t resolution) |
kgills |
0:9a1febb56203 | 149 | { |
kgills |
0:9a1febb56203 | 150 | char data[2]; |
kgills |
0:9a1febb56203 | 151 | |
kgills |
0:9a1febb56203 | 152 | if (i2c_->write(I2C_ADDR, cmd_read_user1, sizeof(cmd_read_user1)) != 0) { |
kgills |
0:9a1febb56203 | 153 | return -1; |
kgills |
0:9a1febb56203 | 154 | } |
kgills |
0:9a1febb56203 | 155 | |
kgills |
0:9a1febb56203 | 156 | if (i2c_->read(I2C_ADDR, &data[1], 1) != 0) { |
kgills |
0:9a1febb56203 | 157 | return -1; |
kgills |
0:9a1febb56203 | 158 | } |
kgills |
0:9a1febb56203 | 159 | |
kgills |
0:9a1febb56203 | 160 | switch (resolution) { |
kgills |
0:9a1febb56203 | 161 | case RH_12b_TEMP_14b: |
kgills |
0:9a1febb56203 | 162 | data[1] &= ~0x81; |
kgills |
0:9a1febb56203 | 163 | break; |
kgills |
0:9a1febb56203 | 164 | case RH_8b_TEMP_12b: |
kgills |
0:9a1febb56203 | 165 | data[1] = (data[1] & ~0x80) | 0x01; |
kgills |
0:9a1febb56203 | 166 | break; |
kgills |
0:9a1febb56203 | 167 | case RH_10b_TEMP_13b: |
kgills |
0:9a1febb56203 | 168 | data[1] = (data[1] & ~0x01) | 0x80; |
kgills |
0:9a1febb56203 | 169 | break; |
kgills |
0:9a1febb56203 | 170 | case RH_11b_TEMP_11b: |
kgills |
0:9a1febb56203 | 171 | data[1] |= 0x81; |
kgills |
0:9a1febb56203 | 172 | break; |
kgills |
0:9a1febb56203 | 173 | default: |
kgills |
0:9a1febb56203 | 174 | return -1; |
kgills |
0:9a1febb56203 | 175 | } |
kgills |
0:9a1febb56203 | 176 | |
kgills |
0:9a1febb56203 | 177 | data[0] = cmd_write_user1[0]; |
kgills |
0:9a1febb56203 | 178 | |
kgills |
0:9a1febb56203 | 179 | if (i2c_->write(I2C_ADDR, data, 2) != 0) { |
kgills |
0:9a1febb56203 | 180 | return -1; |
kgills |
0:9a1febb56203 | 181 | } |
kgills |
0:9a1febb56203 | 182 | |
kgills |
0:9a1febb56203 | 183 | return 0; |
kgills |
0:9a1febb56203 | 184 | } |
kgills |
0:9a1febb56203 | 185 | |
kgills |
0:9a1febb56203 | 186 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 187 | int Si7020::getTemperature(int16_t *tempCx10) |
kgills |
0:9a1febb56203 | 188 | { |
kgills |
0:9a1febb56203 | 189 | if (i2c_->write(I2C_ADDR, cmd_meas_temp, sizeof(cmd_meas_temp)) != 0) { |
kgills |
0:9a1febb56203 | 190 | return -1; |
kgills |
0:9a1febb56203 | 191 | } |
kgills |
0:9a1febb56203 | 192 | |
kgills |
0:9a1febb56203 | 193 | return checkTemperature(tempCx10); |
kgills |
0:9a1febb56203 | 194 | } |
kgills |
0:9a1febb56203 | 195 | |
kgills |
0:9a1febb56203 | 196 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 197 | int Si7020::getTemperature(float *tempC) |
kgills |
0:9a1febb56203 | 198 | { |
kgills |
0:9a1febb56203 | 199 | if (i2c_->write(I2C_ADDR, cmd_meas_temp, sizeof(cmd_meas_temp)) != 0) { |
kgills |
0:9a1febb56203 | 200 | return -1; |
kgills |
0:9a1febb56203 | 201 | } |
kgills |
0:9a1febb56203 | 202 | |
kgills |
0:9a1febb56203 | 203 | return checkTemperature(tempC); |
kgills |
0:9a1febb56203 | 204 | } |
kgills |
0:9a1febb56203 | 205 | |
kgills |
0:9a1febb56203 | 206 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 207 | int Si7020::startTemperature(void) |
kgills |
0:9a1febb56203 | 208 | { |
kgills |
0:9a1febb56203 | 209 | if (i2c_->write(I2C_ADDR, cmd_meas_temp_no_hold, sizeof(cmd_meas_temp_no_hold)) != 0) { |
kgills |
0:9a1febb56203 | 210 | return -1; |
kgills |
0:9a1febb56203 | 211 | } |
kgills |
0:9a1febb56203 | 212 | |
kgills |
0:9a1febb56203 | 213 | return 0; |
kgills |
0:9a1febb56203 | 214 | } |
kgills |
0:9a1febb56203 | 215 | |
kgills |
0:9a1febb56203 | 216 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 217 | int Si7020::checkTemperature(int16_t *tempCx10) |
kgills |
0:9a1febb56203 | 218 | { |
kgills |
0:9a1febb56203 | 219 | char data[3]; |
kgills |
0:9a1febb56203 | 220 | uint16_t code; |
kgills |
0:9a1febb56203 | 221 | int temp; |
kgills |
0:9a1febb56203 | 222 | |
kgills |
0:9a1febb56203 | 223 | if (i2c_->read(I2C_ADDR, data, 3) != 0) { |
kgills |
0:9a1febb56203 | 224 | return -1; |
kgills |
0:9a1febb56203 | 225 | } |
kgills |
0:9a1febb56203 | 226 | |
kgills |
0:9a1febb56203 | 227 | // Get 16-bit value from bytes read |
kgills |
0:9a1febb56203 | 228 | code = ((uint16_t)data[0] << 8) + data[1]; |
kgills |
0:9a1febb56203 | 229 | |
kgills |
0:9a1febb56203 | 230 | // Calculate the temperature using the formula from the datasheet |
kgills |
0:9a1febb56203 | 231 | // Scaled by 100 |
kgills |
0:9a1febb56203 | 232 | temp = ((((int)17572 * code) + 0x8000) >> 16) - 4685; |
kgills |
0:9a1febb56203 | 233 | |
kgills |
0:9a1febb56203 | 234 | // Return value is to be scaled by 10 |
kgills |
0:9a1febb56203 | 235 | *tempCx10 = (temp + 5) / 10; |
kgills |
0:9a1febb56203 | 236 | |
kgills |
0:9a1febb56203 | 237 | return 0; |
kgills |
0:9a1febb56203 | 238 | } |
kgills |
0:9a1febb56203 | 239 | |
kgills |
0:9a1febb56203 | 240 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 241 | int Si7020::checkTemperature(float *tempC) |
kgills |
0:9a1febb56203 | 242 | { |
kgills |
0:9a1febb56203 | 243 | char data[3]; |
kgills |
0:9a1febb56203 | 244 | uint16_t code; |
kgills |
0:9a1febb56203 | 245 | |
kgills |
0:9a1febb56203 | 246 | if (i2c_->read(I2C_ADDR, data, 3) != 0) { |
kgills |
0:9a1febb56203 | 247 | return -1; |
kgills |
0:9a1febb56203 | 248 | } |
kgills |
0:9a1febb56203 | 249 | |
kgills |
0:9a1febb56203 | 250 | // Get 16-bit value from bytes read |
kgills |
0:9a1febb56203 | 251 | code = ((uint16_t)data[0] << 8) + data[1]; |
kgills |
0:9a1febb56203 | 252 | |
kgills |
0:9a1febb56203 | 253 | // Calculate the temperature using the formula from the datasheet |
kgills |
0:9a1febb56203 | 254 | // Scaled by 100 |
kgills |
1:eca9d19c17ab | 255 | *tempC = ((175.72f * (float)code) / 65536.0f) - 46.85f; |
kgills |
0:9a1febb56203 | 256 | |
kgills |
0:9a1febb56203 | 257 | return 0; |
kgills |
0:9a1febb56203 | 258 | } |
kgills |
0:9a1febb56203 | 259 | |
kgills |
0:9a1febb56203 | 260 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 261 | int Si7020::getHumidity(int16_t *humidx10) |
kgills |
0:9a1febb56203 | 262 | { |
kgills |
0:9a1febb56203 | 263 | if (i2c_->write(I2C_ADDR, cmd_meas_humid, sizeof(cmd_meas_humid), true) != 0) { |
kgills |
0:9a1febb56203 | 264 | return -1; |
kgills |
0:9a1febb56203 | 265 | } |
kgills |
0:9a1febb56203 | 266 | |
kgills |
0:9a1febb56203 | 267 | return checkHumidity(humidx10); |
kgills |
0:9a1febb56203 | 268 | } |
kgills |
0:9a1febb56203 | 269 | |
kgills |
0:9a1febb56203 | 270 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 271 | int Si7020::getHumidity(float *humid) |
kgills |
0:9a1febb56203 | 272 | { |
kgills |
0:9a1febb56203 | 273 | if (i2c_->write(I2C_ADDR, cmd_meas_humid, sizeof(cmd_meas_humid)) != 0) { |
kgills |
0:9a1febb56203 | 274 | return -1; |
kgills |
0:9a1febb56203 | 275 | } |
kgills |
0:9a1febb56203 | 276 | |
kgills |
0:9a1febb56203 | 277 | return checkHumidity(humid); |
kgills |
0:9a1febb56203 | 278 | } |
kgills |
0:9a1febb56203 | 279 | |
kgills |
0:9a1febb56203 | 280 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 281 | int Si7020::startHumidity(void) |
kgills |
0:9a1febb56203 | 282 | { |
kgills |
0:9a1febb56203 | 283 | if (i2c_->write(I2C_ADDR, cmd_meas_humid_no_hold, sizeof(cmd_meas_humid_no_hold)) != 0) { |
kgills |
0:9a1febb56203 | 284 | return -1; |
kgills |
0:9a1febb56203 | 285 | } |
kgills |
0:9a1febb56203 | 286 | |
kgills |
0:9a1febb56203 | 287 | return 0; |
kgills |
0:9a1febb56203 | 288 | } |
kgills |
0:9a1febb56203 | 289 | |
kgills |
0:9a1febb56203 | 290 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 291 | int Si7020::checkHumidity(int16_t *humidx10) |
kgills |
0:9a1febb56203 | 292 | { |
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0:9a1febb56203 | 293 | char data[3]; |
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0:9a1febb56203 | 294 | uint16_t code; |
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0:9a1febb56203 | 295 | |
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0:9a1febb56203 | 296 | if (i2c_->read(I2C_ADDR, data, 3) != 0) { |
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0:9a1febb56203 | 297 | return -1; |
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0:9a1febb56203 | 298 | } |
kgills |
0:9a1febb56203 | 299 | |
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0:9a1febb56203 | 300 | // Get 16-bit value from bytes read |
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0:9a1febb56203 | 301 | code = ((uint16_t)data[0] << 8) + data[1]; |
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0:9a1febb56203 | 302 | |
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0:9a1febb56203 | 303 | // Calculate the humidity using the formula from the datasheet |
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0:9a1febb56203 | 304 | // Scaled by 10 |
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0:9a1febb56203 | 305 | *humidx10 = ((((int)1250 * code) + 0x8000) >> 16) - 60; |
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0:9a1febb56203 | 306 | |
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0:9a1febb56203 | 307 | // Check the crc |
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0:9a1febb56203 | 308 | char crc = crc8(data[0], 0x00); |
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0:9a1febb56203 | 309 | crc = crc8(data[1], crc); |
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0:9a1febb56203 | 310 | if(crc != data[2]) { |
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0:9a1febb56203 | 311 | return -1; |
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0:9a1febb56203 | 312 | } |
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0:9a1febb56203 | 313 | |
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0:9a1febb56203 | 314 | return 0; |
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0:9a1febb56203 | 315 | } |
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0:9a1febb56203 | 316 | |
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0:9a1febb56203 | 317 | //****************************************************************************** |
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0:9a1febb56203 | 318 | int Si7020::checkHumidity(float *humid) |
kgills |
0:9a1febb56203 | 319 | { |
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0:9a1febb56203 | 320 | char data[3]; |
kgills |
0:9a1febb56203 | 321 | uint16_t code; |
kgills |
0:9a1febb56203 | 322 | |
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0:9a1febb56203 | 323 | if (i2c_->read(I2C_ADDR, data, 3) != 0) { |
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0:9a1febb56203 | 324 | return -1; |
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0:9a1febb56203 | 325 | } |
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0:9a1febb56203 | 326 | |
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0:9a1febb56203 | 327 | // Get 16-bit value from bytes read |
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0:9a1febb56203 | 328 | code = ((uint16_t)data[0] << 8) + data[1]; |
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0:9a1febb56203 | 329 | |
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0:9a1febb56203 | 330 | // Calculate the humidity using the formula from the datasheet |
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1:eca9d19c17ab | 331 | *humid = ((125.0f * (float)code) / 65536.0f) - 6.0f; |
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0:9a1febb56203 | 332 | |
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0:9a1febb56203 | 333 | return 0; |
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0:9a1febb56203 | 334 | } |
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0:9a1febb56203 | 335 | |
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0:9a1febb56203 | 336 | //****************************************************************************** |
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0:9a1febb56203 | 337 | int Si7020::getPrevTemperature(float *tempC) { |
kgills |
0:9a1febb56203 | 338 | |
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0:9a1febb56203 | 339 | if (i2c_->write(I2C_ADDR, cmd_meas_prev_temp, sizeof(cmd_meas_prev_temp)) != 0) { |
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0:9a1febb56203 | 340 | return -1; |
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0:9a1febb56203 | 341 | } |
kgills |
0:9a1febb56203 | 342 | |
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0:9a1febb56203 | 343 | if(checkTemperature(tempC) != 0) { |
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0:9a1febb56203 | 344 | return -1; |
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0:9a1febb56203 | 345 | } |
kgills |
0:9a1febb56203 | 346 | |
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0:9a1febb56203 | 347 | return 0; |
kgills |
0:9a1febb56203 | 348 | } |
kgills |
0:9a1febb56203 | 349 | |
kgills |
0:9a1febb56203 | 350 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 351 | int Si7020::getPrevTemperature(int16_t *tempCx10) { |
kgills |
0:9a1febb56203 | 352 | |
kgills |
0:9a1febb56203 | 353 | if (i2c_->write(I2C_ADDR, cmd_meas_prev_temp, sizeof(cmd_meas_prev_temp)) != 0) { |
kgills |
0:9a1febb56203 | 354 | return -1; |
kgills |
0:9a1febb56203 | 355 | } |
kgills |
0:9a1febb56203 | 356 | |
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0:9a1febb56203 | 357 | if(checkTemperature(tempCx10) != 0) { |
kgills |
0:9a1febb56203 | 358 | return -1; |
kgills |
0:9a1febb56203 | 359 | } |
kgills |
0:9a1febb56203 | 360 | |
kgills |
0:9a1febb56203 | 361 | return 0; |
kgills |
0:9a1febb56203 | 362 | } |
kgills |
0:9a1febb56203 | 363 | |
kgills |
0:9a1febb56203 | 364 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 365 | int Si7020::getRev(char *rev) |
kgills |
0:9a1febb56203 | 366 | { |
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0:9a1febb56203 | 367 | if (i2c_->write(I2C_ADDR, cmd_fw_ver, sizeof(cmd_fw_ver)) != 0) { |
kgills |
0:9a1febb56203 | 368 | return -1; |
kgills |
0:9a1febb56203 | 369 | } |
kgills |
0:9a1febb56203 | 370 | |
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0:9a1febb56203 | 371 | if (i2c_->read(I2C_ADDR, rev, 1) != 0) { |
kgills |
0:9a1febb56203 | 372 | return -1; |
kgills |
0:9a1febb56203 | 373 | } |
kgills |
0:9a1febb56203 | 374 | |
kgills |
0:9a1febb56203 | 375 | return 0; |
kgills |
0:9a1febb56203 | 376 | } |
kgills |
0:9a1febb56203 | 377 | |
kgills |
0:9a1febb56203 | 378 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 379 | int Si7020::heater(bool enable) |
kgills |
0:9a1febb56203 | 380 | { |
kgills |
0:9a1febb56203 | 381 | char data[2]; |
kgills |
0:9a1febb56203 | 382 | |
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0:9a1febb56203 | 383 | if (i2c_->write(I2C_ADDR, cmd_read_user1, sizeof(cmd_read_user1)) != 0) { |
kgills |
0:9a1febb56203 | 384 | return -1; |
kgills |
0:9a1febb56203 | 385 | } |
kgills |
0:9a1febb56203 | 386 | |
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0:9a1febb56203 | 387 | if (i2c_->read(I2C_ADDR, &data[1], 1) != 0) { |
kgills |
0:9a1febb56203 | 388 | return -1; |
kgills |
0:9a1febb56203 | 389 | } |
kgills |
0:9a1febb56203 | 390 | |
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0:9a1febb56203 | 391 | if (enable) { |
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0:9a1febb56203 | 392 | data[1] |= 0x04; |
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0:9a1febb56203 | 393 | } else { |
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0:9a1febb56203 | 394 | data[1] &= ~0x04; |
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0:9a1febb56203 | 395 | } |
kgills |
0:9a1febb56203 | 396 | |
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0:9a1febb56203 | 397 | data[0] = cmd_write_user1[0]; |
kgills |
0:9a1febb56203 | 398 | |
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0:9a1febb56203 | 399 | if (i2c_->write(I2C_ADDR, data, 2) != 0) { |
kgills |
0:9a1febb56203 | 400 | return -1; |
kgills |
0:9a1febb56203 | 401 | } |
kgills |
0:9a1febb56203 | 402 | |
kgills |
0:9a1febb56203 | 403 | return 0; |
kgills |
0:9a1febb56203 | 404 | } |
kgills |
0:9a1febb56203 | 405 | |
kgills |
0:9a1febb56203 | 406 | //****************************************************************************** |
kgills |
0:9a1febb56203 | 407 | char Si7020::crc8(char value, char seed) |
kgills |
0:9a1febb56203 | 408 | { |
kgills |
0:9a1febb56203 | 409 | int i; |
kgills |
0:9a1febb56203 | 410 | |
kgills |
0:9a1febb56203 | 411 | for (i = 0; i < 8; i++) { |
kgills |
0:9a1febb56203 | 412 | |
kgills |
0:9a1febb56203 | 413 | if ((value ^ seed) & 0x80) { |
kgills |
0:9a1febb56203 | 414 | seed <<= 1; |
kgills |
0:9a1febb56203 | 415 | seed ^= POLYVAL; |
kgills |
0:9a1febb56203 | 416 | } else { |
kgills |
0:9a1febb56203 | 417 | seed <<= 1; |
kgills |
0:9a1febb56203 | 418 | } |
kgills |
0:9a1febb56203 | 419 | |
kgills |
0:9a1febb56203 | 420 | value <<= 1; |
kgills |
0:9a1febb56203 | 421 | } |
kgills |
0:9a1febb56203 | 422 | |
kgills |
0:9a1febb56203 | 423 | return seed; |
kgills |
0:9a1febb56203 | 424 | } |