Interface library for the Sensirion SHT7x series humidity and temperature sensors.
This was developed and tested on the LPC1768 board.
Currently, it doesn't work for LPC11U24. I'm investigating why.
sht7x.cpp@0:f1a93e55feb5, 2013-08-11 (annotated)
- Committer:
- JacobBramley
- Date:
- Sun Aug 11 18:11:05 2013 +0000
- Revision:
- 0:f1a93e55feb5
First Mbed release of the Sensirion SHT7x interface library.
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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JacobBramley | 0:f1a93e55feb5 | 1 | // Copyright (c) 2013 Jacob Bramley |
JacobBramley | 0:f1a93e55feb5 | 2 | // |
JacobBramley | 0:f1a93e55feb5 | 3 | // Permission is hereby granted, free of charge, to any person obtaining a copy |
JacobBramley | 0:f1a93e55feb5 | 4 | // of this software and associated documentation files (the "Software"), to deal |
JacobBramley | 0:f1a93e55feb5 | 5 | // in the Software without restriction, including without limitation the rights |
JacobBramley | 0:f1a93e55feb5 | 6 | // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
JacobBramley | 0:f1a93e55feb5 | 7 | // copies of the Software, and to permit persons to whom the Software is |
JacobBramley | 0:f1a93e55feb5 | 8 | // furnished to do so, subject to the following conditions: |
JacobBramley | 0:f1a93e55feb5 | 9 | // |
JacobBramley | 0:f1a93e55feb5 | 10 | // The above copyright notice and this permission notice shall be included in |
JacobBramley | 0:f1a93e55feb5 | 11 | // all copies or substantial portions of the Software. |
JacobBramley | 0:f1a93e55feb5 | 12 | // |
JacobBramley | 0:f1a93e55feb5 | 13 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
JacobBramley | 0:f1a93e55feb5 | 14 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
JacobBramley | 0:f1a93e55feb5 | 15 | // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
JacobBramley | 0:f1a93e55feb5 | 16 | // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
JacobBramley | 0:f1a93e55feb5 | 17 | // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
JacobBramley | 0:f1a93e55feb5 | 18 | // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
JacobBramley | 0:f1a93e55feb5 | 19 | // SOFTWARE. |
JacobBramley | 0:f1a93e55feb5 | 20 | |
JacobBramley | 0:f1a93e55feb5 | 21 | #define __STC_LIMIT_MACROS |
JacobBramley | 0:f1a93e55feb5 | 22 | #include <stdint.h> |
JacobBramley | 0:f1a93e55feb5 | 23 | #include <stddef.h> |
JacobBramley | 0:f1a93e55feb5 | 24 | #include <new> |
JacobBramley | 0:f1a93e55feb5 | 25 | #include <math.h> |
JacobBramley | 0:f1a93e55feb5 | 26 | #include <limits> |
JacobBramley | 0:f1a93e55feb5 | 27 | #include "mbed.h" |
JacobBramley | 0:f1a93e55feb5 | 28 | #include "sht7x.h" |
JacobBramley | 0:f1a93e55feb5 | 29 | |
JacobBramley | 0:f1a93e55feb5 | 30 | // For some reason, Mbed's stdint.h doesn't define INT64_MIN. |
JacobBramley | 0:f1a93e55feb5 | 31 | #ifndef INT64_MIN |
JacobBramley | 0:f1a93e55feb5 | 32 | #define INT64_MIN (-0x8000000000000000) |
JacobBramley | 0:f1a93e55feb5 | 33 | #endif |
JacobBramley | 0:f1a93e55feb5 | 34 | |
JacobBramley | 0:f1a93e55feb5 | 35 | #ifdef TARGET_LPC11U24 |
JacobBramley | 0:f1a93e55feb5 | 36 | #define SLEEP() sleep() |
JacobBramley | 0:f1a93e55feb5 | 37 | #else |
JacobBramley | 0:f1a93e55feb5 | 38 | #define SLEEP() /* Busy-wait */ |
JacobBramley | 0:f1a93e55feb5 | 39 | #endif |
JacobBramley | 0:f1a93e55feb5 | 40 | |
JacobBramley | 0:f1a93e55feb5 | 41 | namespace sht7x { |
JacobBramley | 0:f1a93e55feb5 | 42 | |
JacobBramley | 0:f1a93e55feb5 | 43 | // ==== Public interface. ==== |
JacobBramley | 0:f1a93e55feb5 | 44 | |
JacobBramley | 0:f1a93e55feb5 | 45 | SHT7x::SHT7x(PinName sck, PinName sda) |
JacobBramley | 0:f1a93e55feb5 | 46 | : sck_(DigitalOut(sck)), sda_(DigitalInOut(sda)) { |
JacobBramley | 0:f1a93e55feb5 | 47 | sck_state_ = PIN_INVALID; |
JacobBramley | 0:f1a93e55feb5 | 48 | sda_state_ = PIN_INVALID; |
JacobBramley | 0:f1a93e55feb5 | 49 | state_ = STATE_UNKNOWN; |
JacobBramley | 0:f1a93e55feb5 | 50 | |
JacobBramley | 0:f1a93e55feb5 | 51 | // The default sensor configuration, according to the datasheet. |
JacobBramley | 0:f1a93e55feb5 | 52 | status_.precision = PRECISION_HIGH; |
JacobBramley | 0:f1a93e55feb5 | 53 | status_.otp = OTP_ON; |
JacobBramley | 0:f1a93e55feb5 | 54 | status_.heater = HEATER_OFF; |
JacobBramley | 0:f1a93e55feb5 | 55 | status_.battery = BATTERY_GT_2_47; |
JacobBramley | 0:f1a93e55feb5 | 56 | |
JacobBramley | 0:f1a93e55feb5 | 57 | // Configure the pins, but do nothing else at this point. |
JacobBramley | 0:f1a93e55feb5 | 58 | sda_.mode(OpenDrain); |
JacobBramley | 0:f1a93e55feb5 | 59 | sda_.output(); |
JacobBramley | 0:f1a93e55feb5 | 60 | this->set_sda(PIN_FREE); |
JacobBramley | 0:f1a93e55feb5 | 61 | this->set_sck(PIN_0); |
JacobBramley | 0:f1a93e55feb5 | 62 | } |
JacobBramley | 0:f1a93e55feb5 | 63 | |
JacobBramley | 0:f1a93e55feb5 | 64 | |
JacobBramley | 0:f1a93e55feb5 | 65 | bool SHT7x::reset() { |
JacobBramley | 0:f1a93e55feb5 | 66 | if (!check_state(STATE_UNKNOWN, STATE_SLEEP, STATE_COMMS_ERROR)) { |
JacobBramley | 0:f1a93e55feb5 | 67 | return false; |
JacobBramley | 0:f1a93e55feb5 | 68 | } |
JacobBramley | 0:f1a93e55feb5 | 69 | state_ = STATE_RESETTING; |
JacobBramley | 0:f1a93e55feb5 | 70 | |
JacobBramley | 0:f1a93e55feb5 | 71 | // If we're trying to reset the sensor, it's likely that the communications |
JacobBramley | 0:f1a93e55feb5 | 72 | // channel has got into a weird state. We need it up and running in order to |
JacobBramley | 0:f1a93e55feb5 | 73 | // send the reset command. |
JacobBramley | 0:f1a93e55feb5 | 74 | reset_comms(); |
JacobBramley | 0:f1a93e55feb5 | 75 | |
JacobBramley | 0:f1a93e55feb5 | 76 | command(CMD_RESET); |
JacobBramley | 0:f1a93e55feb5 | 77 | state_ = STATE_UNKNOWN; |
JacobBramley | 0:f1a93e55feb5 | 78 | |
JacobBramley | 0:f1a93e55feb5 | 79 | status_.precision = PRECISION_HIGH; |
JacobBramley | 0:f1a93e55feb5 | 80 | status_.otp = OTP_ON; |
JacobBramley | 0:f1a93e55feb5 | 81 | status_.heater = HEATER_OFF; |
JacobBramley | 0:f1a93e55feb5 | 82 | status_.battery = BATTERY_GT_2_47; |
JacobBramley | 0:f1a93e55feb5 | 83 | |
JacobBramley | 0:f1a93e55feb5 | 84 | return true; |
JacobBramley | 0:f1a93e55feb5 | 85 | } |
JacobBramley | 0:f1a93e55feb5 | 86 | |
JacobBramley | 0:f1a93e55feb5 | 87 | |
JacobBramley | 0:f1a93e55feb5 | 88 | bool SHT7x::initialize() { |
JacobBramley | 0:f1a93e55feb5 | 89 | if (!check_state(STATE_UNKNOWN)) { |
JacobBramley | 0:f1a93e55feb5 | 90 | return false; |
JacobBramley | 0:f1a93e55feb5 | 91 | } |
JacobBramley | 0:f1a93e55feb5 | 92 | state_ = STATE_INITIALIZING; |
JacobBramley | 0:f1a93e55feb5 | 93 | |
JacobBramley | 0:f1a93e55feb5 | 94 | // Wait for the sensor to turn on. |
JacobBramley | 0:f1a93e55feb5 | 95 | // There is no external notification that the sensor is ready, so a timer |
JacobBramley | 0:f1a93e55feb5 | 96 | // is the only option here. |
JacobBramley | 0:f1a93e55feb5 | 97 | wait_us(time_reset()); |
JacobBramley | 0:f1a93e55feb5 | 98 | |
JacobBramley | 0:f1a93e55feb5 | 99 | state_ = STATE_SLEEP; |
JacobBramley | 0:f1a93e55feb5 | 100 | |
JacobBramley | 0:f1a93e55feb5 | 101 | // Make sure that the cached status byte is up to date. |
JacobBramley | 0:f1a93e55feb5 | 102 | return status(); |
JacobBramley | 0:f1a93e55feb5 | 103 | } |
JacobBramley | 0:f1a93e55feb5 | 104 | |
JacobBramley | 0:f1a93e55feb5 | 105 | |
JacobBramley | 0:f1a93e55feb5 | 106 | bool SHT7x::configure(Precision precision, OTP otp, Heater heater) { |
JacobBramley | 0:f1a93e55feb5 | 107 | if (!check_state(STATE_SLEEP)) { |
JacobBramley | 0:f1a93e55feb5 | 108 | return false; |
JacobBramley | 0:f1a93e55feb5 | 109 | } |
JacobBramley | 0:f1a93e55feb5 | 110 | state_ = STATE_SETTING_CONFIGURATION; |
JacobBramley | 0:f1a93e55feb5 | 111 | |
JacobBramley | 0:f1a93e55feb5 | 112 | // Overlay the new status on the existing one. |
JacobBramley | 0:f1a93e55feb5 | 113 | if (precision != PRECISION_KEEP) { status_.precision = precision; } |
JacobBramley | 0:f1a93e55feb5 | 114 | if (otp != OTP_KEEP) { status_.otp = otp; } |
JacobBramley | 0:f1a93e55feb5 | 115 | if (heater != HEATER_KEEP) { status_.heater = heater; } |
JacobBramley | 0:f1a93e55feb5 | 116 | |
JacobBramley | 0:f1a93e55feb5 | 117 | // Write the status byte. |
JacobBramley | 0:f1a93e55feb5 | 118 | command(CMD_WRITE_STATUS); |
JacobBramley | 0:f1a93e55feb5 | 119 | put_byte(encode_status_byte()); |
JacobBramley | 0:f1a93e55feb5 | 120 | get_ack(); |
JacobBramley | 0:f1a93e55feb5 | 121 | |
JacobBramley | 0:f1a93e55feb5 | 122 | // TODO: It's not obvious how to get a CRC byte from this command. Is it |
JacobBramley | 0:f1a93e55feb5 | 123 | // necessary to read the status back again? |
JacobBramley | 0:f1a93e55feb5 | 124 | |
JacobBramley | 0:f1a93e55feb5 | 125 | state_ = STATE_SLEEP; |
JacobBramley | 0:f1a93e55feb5 | 126 | return true; |
JacobBramley | 0:f1a93e55feb5 | 127 | } |
JacobBramley | 0:f1a93e55feb5 | 128 | |
JacobBramley | 0:f1a93e55feb5 | 129 | |
JacobBramley | 0:f1a93e55feb5 | 130 | bool SHT7x::status() { |
JacobBramley | 0:f1a93e55feb5 | 131 | if (!check_state(STATE_SLEEP)) { |
JacobBramley | 0:f1a93e55feb5 | 132 | return false; |
JacobBramley | 0:f1a93e55feb5 | 133 | } |
JacobBramley | 0:f1a93e55feb5 | 134 | |
JacobBramley | 0:f1a93e55feb5 | 135 | // Read the status register to populate the cached values. |
JacobBramley | 0:f1a93e55feb5 | 136 | command(CMD_READ_STATUS); |
JacobBramley | 0:f1a93e55feb5 | 137 | uint32_t raw = get_byte(); |
JacobBramley | 0:f1a93e55feb5 | 138 | put_ack(0); |
JacobBramley | 0:f1a93e55feb5 | 139 | uint32_t crc = get_byte(); |
JacobBramley | 0:f1a93e55feb5 | 140 | put_ack(1); |
JacobBramley | 0:f1a93e55feb5 | 141 | |
JacobBramley | 0:f1a93e55feb5 | 142 | // We must decode the status byte before checking the CRC because the status |
JacobBramley | 0:f1a93e55feb5 | 143 | // register is used to initialize the CRC check. |
JacobBramley | 0:f1a93e55feb5 | 144 | decode_status_byte(raw); |
JacobBramley | 0:f1a93e55feb5 | 145 | |
JacobBramley | 0:f1a93e55feb5 | 146 | if (check_crc(CMD_READ_STATUS, raw, crc)) { |
JacobBramley | 0:f1a93e55feb5 | 147 | state_ = STATE_SLEEP; |
JacobBramley | 0:f1a93e55feb5 | 148 | } else { |
JacobBramley | 0:f1a93e55feb5 | 149 | state_ = STATE_COMMS_ERROR; |
JacobBramley | 0:f1a93e55feb5 | 150 | } |
JacobBramley | 0:f1a93e55feb5 | 151 | |
JacobBramley | 0:f1a93e55feb5 | 152 | return true; |
JacobBramley | 0:f1a93e55feb5 | 153 | } |
JacobBramley | 0:f1a93e55feb5 | 154 | |
JacobBramley | 0:f1a93e55feb5 | 155 | |
JacobBramley | 0:f1a93e55feb5 | 156 | bool SHT7x::status(Status * & status) { |
JacobBramley | 0:f1a93e55feb5 | 157 | if (this->status()) { |
JacobBramley | 0:f1a93e55feb5 | 158 | status = &status_; |
JacobBramley | 0:f1a93e55feb5 | 159 | return true; |
JacobBramley | 0:f1a93e55feb5 | 160 | } |
JacobBramley | 0:f1a93e55feb5 | 161 | return false; |
JacobBramley | 0:f1a93e55feb5 | 162 | } |
JacobBramley | 0:f1a93e55feb5 | 163 | |
JacobBramley | 0:f1a93e55feb5 | 164 | |
JacobBramley | 0:f1a93e55feb5 | 165 | bool SHT7x::measure(Temp & temp, uint32_t mvdd) { |
JacobBramley | 0:f1a93e55feb5 | 166 | if (!check_state(STATE_SLEEP)) { |
JacobBramley | 0:f1a93e55feb5 | 167 | return false; |
JacobBramley | 0:f1a93e55feb5 | 168 | } |
JacobBramley | 0:f1a93e55feb5 | 169 | state_ = STATE_MEASURING_TEMPERATURE; |
JacobBramley | 0:f1a93e55feb5 | 170 | |
JacobBramley | 0:f1a93e55feb5 | 171 | // TODO: Wait for sda low, rather than a timer. |
JacobBramley | 0:f1a93e55feb5 | 172 | command(CMD_READ_TEMP); |
JacobBramley | 0:f1a93e55feb5 | 173 | wait_us(time_reading_temperature()); |
JacobBramley | 0:f1a93e55feb5 | 174 | |
JacobBramley | 0:f1a93e55feb5 | 175 | uint32_t raw = get_byte() << 8; |
JacobBramley | 0:f1a93e55feb5 | 176 | put_ack(0); |
JacobBramley | 0:f1a93e55feb5 | 177 | raw |= get_byte() << 0; |
JacobBramley | 0:f1a93e55feb5 | 178 | put_ack(0); |
JacobBramley | 0:f1a93e55feb5 | 179 | uint32_t crc = get_byte(); |
JacobBramley | 0:f1a93e55feb5 | 180 | put_ack(1); |
JacobBramley | 0:f1a93e55feb5 | 181 | |
JacobBramley | 0:f1a93e55feb5 | 182 | if (check_crc(CMD_READ_TEMP, raw, crc)) { |
JacobBramley | 0:f1a93e55feb5 | 183 | new (&temp) Temp(bits_required_temperature(), raw, mvdd); |
JacobBramley | 0:f1a93e55feb5 | 184 | state_ = STATE_SLEEP; |
JacobBramley | 0:f1a93e55feb5 | 185 | |
JacobBramley | 0:f1a93e55feb5 | 186 | // Make sure that the cached status byte is up to date. |
JacobBramley | 0:f1a93e55feb5 | 187 | // In particular, the Vdd voltage detection is updated after a measurement. |
JacobBramley | 0:f1a93e55feb5 | 188 | return status(); |
JacobBramley | 0:f1a93e55feb5 | 189 | } |
JacobBramley | 0:f1a93e55feb5 | 190 | |
JacobBramley | 0:f1a93e55feb5 | 191 | new (&temp) Temp(); |
JacobBramley | 0:f1a93e55feb5 | 192 | state_ = STATE_COMMS_ERROR; |
JacobBramley | 0:f1a93e55feb5 | 193 | return false; |
JacobBramley | 0:f1a93e55feb5 | 194 | } |
JacobBramley | 0:f1a93e55feb5 | 195 | |
JacobBramley | 0:f1a93e55feb5 | 196 | |
JacobBramley | 0:f1a93e55feb5 | 197 | bool SHT7x::measure(Hum & hum, Temp const * temp) { |
JacobBramley | 0:f1a93e55feb5 | 198 | if (!check_state(STATE_SLEEP)) { |
JacobBramley | 0:f1a93e55feb5 | 199 | return false; |
JacobBramley | 0:f1a93e55feb5 | 200 | } |
JacobBramley | 0:f1a93e55feb5 | 201 | state_ = STATE_MEASURING_HUMIDITY; |
JacobBramley | 0:f1a93e55feb5 | 202 | |
JacobBramley | 0:f1a93e55feb5 | 203 | // TODO: Wait for sda low, rather than a timer. |
JacobBramley | 0:f1a93e55feb5 | 204 | command(CMD_READ_HUM); |
JacobBramley | 0:f1a93e55feb5 | 205 | wait_us(time_reading_humidity()); |
JacobBramley | 0:f1a93e55feb5 | 206 | |
JacobBramley | 0:f1a93e55feb5 | 207 | // Two bytes are sent even for 8-bit humidity readings. |
JacobBramley | 0:f1a93e55feb5 | 208 | uint32_t raw = get_byte() << 8; |
JacobBramley | 0:f1a93e55feb5 | 209 | put_ack(0); |
JacobBramley | 0:f1a93e55feb5 | 210 | raw |= get_byte() << 0; |
JacobBramley | 0:f1a93e55feb5 | 211 | put_ack(0); |
JacobBramley | 0:f1a93e55feb5 | 212 | uint32_t crc = get_byte(); |
JacobBramley | 0:f1a93e55feb5 | 213 | put_ack(1); |
JacobBramley | 0:f1a93e55feb5 | 214 | |
JacobBramley | 0:f1a93e55feb5 | 215 | if (check_crc(CMD_READ_HUM, raw, crc)) { |
JacobBramley | 0:f1a93e55feb5 | 216 | new (&hum) Hum(bits_required_humidity(), raw, temp); |
JacobBramley | 0:f1a93e55feb5 | 217 | state_ = STATE_SLEEP; |
JacobBramley | 0:f1a93e55feb5 | 218 | |
JacobBramley | 0:f1a93e55feb5 | 219 | // Make sure that the cached status byte is up to date. |
JacobBramley | 0:f1a93e55feb5 | 220 | // In particular, the Vdd voltage detection is updated after a measurement. |
JacobBramley | 0:f1a93e55feb5 | 221 | return status(); |
JacobBramley | 0:f1a93e55feb5 | 222 | } |
JacobBramley | 0:f1a93e55feb5 | 223 | |
JacobBramley | 0:f1a93e55feb5 | 224 | new (&hum) Hum(); |
JacobBramley | 0:f1a93e55feb5 | 225 | state_ = STATE_COMMS_ERROR; |
JacobBramley | 0:f1a93e55feb5 | 226 | return false; |
JacobBramley | 0:f1a93e55feb5 | 227 | } |
JacobBramley | 0:f1a93e55feb5 | 228 | |
JacobBramley | 0:f1a93e55feb5 | 229 | |
JacobBramley | 0:f1a93e55feb5 | 230 | // ==== Internal methods. ==== |
JacobBramley | 0:f1a93e55feb5 | 231 | |
JacobBramley | 0:f1a93e55feb5 | 232 | // Construct a status register value, suitable for writing with |
JacobBramley | 0:f1a93e55feb5 | 233 | // CMD_WRITE_STATUS, from cached values. |
JacobBramley | 0:f1a93e55feb5 | 234 | uint32_t SHT7x::encode_status_byte() const { |
JacobBramley | 0:f1a93e55feb5 | 235 | uint8_t value = 0; |
JacobBramley | 0:f1a93e55feb5 | 236 | value |= (status_.precision == PRECISION_LOW ) ? (0x01) : (0x00); |
JacobBramley | 0:f1a93e55feb5 | 237 | value |= (status_.otp == OTP_OFF ) ? (0x02) : (0x00); |
JacobBramley | 0:f1a93e55feb5 | 238 | value |= (status_.heater == HEATER_ON ) ? (0x04) : (0x00); |
JacobBramley | 0:f1a93e55feb5 | 239 | value |= (status_.battery == BATTERY_LT_2_47) ? (0x40) : (0x00); |
JacobBramley | 0:f1a93e55feb5 | 240 | return value; |
JacobBramley | 0:f1a93e55feb5 | 241 | } |
JacobBramley | 0:f1a93e55feb5 | 242 | |
JacobBramley | 0:f1a93e55feb5 | 243 | |
JacobBramley | 0:f1a93e55feb5 | 244 | // Update the cached status values with a status register value obtained from |
JacobBramley | 0:f1a93e55feb5 | 245 | // the sensor using CMD_READ_STATUS. |
JacobBramley | 0:f1a93e55feb5 | 246 | void SHT7x::decode_status_byte(uint32_t value) { |
JacobBramley | 0:f1a93e55feb5 | 247 | status_.precision = (value & 0x01) ? PRECISION_LOW : PRECISION_HIGH; |
JacobBramley | 0:f1a93e55feb5 | 248 | status_.otp = (value & 0x02) ? OTP_OFF : OTP_ON; |
JacobBramley | 0:f1a93e55feb5 | 249 | status_.heater = (value & 0x04) ? HEATER_ON : HEATER_OFF; |
JacobBramley | 0:f1a93e55feb5 | 250 | status_.battery = (value & 0x40) ? BATTERY_LT_2_47 : BATTERY_GT_2_47; |
JacobBramley | 0:f1a93e55feb5 | 251 | } |
JacobBramley | 0:f1a93e55feb5 | 252 | |
JacobBramley | 0:f1a93e55feb5 | 253 | |
JacobBramley | 0:f1a93e55feb5 | 254 | inline uint32_t SHT7x::bits_required_temperature() const { |
JacobBramley | 0:f1a93e55feb5 | 255 | switch (status_.precision) { |
JacobBramley | 0:f1a93e55feb5 | 256 | default: |
JacobBramley | 0:f1a93e55feb5 | 257 | case PRECISION_HIGH: return 14; |
JacobBramley | 0:f1a93e55feb5 | 258 | case PRECISION_LOW: return 12; |
JacobBramley | 0:f1a93e55feb5 | 259 | } |
JacobBramley | 0:f1a93e55feb5 | 260 | } |
JacobBramley | 0:f1a93e55feb5 | 261 | |
JacobBramley | 0:f1a93e55feb5 | 262 | |
JacobBramley | 0:f1a93e55feb5 | 263 | inline uint32_t SHT7x::bits_required_humidity() const { |
JacobBramley | 0:f1a93e55feb5 | 264 | switch (status_.precision) { |
JacobBramley | 0:f1a93e55feb5 | 265 | default: |
JacobBramley | 0:f1a93e55feb5 | 266 | case PRECISION_HIGH: return 12; |
JacobBramley | 0:f1a93e55feb5 | 267 | case PRECISION_LOW: return 8; |
JacobBramley | 0:f1a93e55feb5 | 268 | } |
JacobBramley | 0:f1a93e55feb5 | 269 | } |
JacobBramley | 0:f1a93e55feb5 | 270 | |
JacobBramley | 0:f1a93e55feb5 | 271 | |
JacobBramley | 0:f1a93e55feb5 | 272 | inline uint32_t SHT7x::time_atom() const { |
JacobBramley | 0:f1a93e55feb5 | 273 | return 1; |
JacobBramley | 0:f1a93e55feb5 | 274 | } |
JacobBramley | 0:f1a93e55feb5 | 275 | |
JacobBramley | 0:f1a93e55feb5 | 276 | |
JacobBramley | 0:f1a93e55feb5 | 277 | inline uint32_t SHT7x::time_reset() const { |
JacobBramley | 0:f1a93e55feb5 | 278 | return 11000; |
JacobBramley | 0:f1a93e55feb5 | 279 | } |
JacobBramley | 0:f1a93e55feb5 | 280 | |
JacobBramley | 0:f1a93e55feb5 | 281 | |
JacobBramley | 0:f1a93e55feb5 | 282 | inline uint32_t SHT7x::time_reading_temperature() const { |
JacobBramley | 0:f1a93e55feb5 | 283 | switch (status_.precision) { |
JacobBramley | 0:f1a93e55feb5 | 284 | default: |
JacobBramley | 0:f1a93e55feb5 | 285 | case PRECISION_HIGH: return 320000; // 320ms, 14 bits |
JacobBramley | 0:f1a93e55feb5 | 286 | case PRECISION_LOW: return 80000; // 80ms, 12 bits |
JacobBramley | 0:f1a93e55feb5 | 287 | } |
JacobBramley | 0:f1a93e55feb5 | 288 | } |
JacobBramley | 0:f1a93e55feb5 | 289 | |
JacobBramley | 0:f1a93e55feb5 | 290 | |
JacobBramley | 0:f1a93e55feb5 | 291 | inline uint32_t SHT7x::time_reading_humidity() const { |
JacobBramley | 0:f1a93e55feb5 | 292 | switch (status_.precision) { |
JacobBramley | 0:f1a93e55feb5 | 293 | default: |
JacobBramley | 0:f1a93e55feb5 | 294 | case PRECISION_HIGH: return 80000; // 80ms, 12 bits |
JacobBramley | 0:f1a93e55feb5 | 295 | case PRECISION_LOW: return 20000; // 20ms, 8 bits |
JacobBramley | 0:f1a93e55feb5 | 296 | } |
JacobBramley | 0:f1a93e55feb5 | 297 | } |
JacobBramley | 0:f1a93e55feb5 | 298 | |
JacobBramley | 0:f1a93e55feb5 | 299 | |
JacobBramley | 0:f1a93e55feb5 | 300 | void SHT7x::start() { |
JacobBramley | 0:f1a93e55feb5 | 301 | uint32_t const t = time_atom(); |
JacobBramley | 0:f1a93e55feb5 | 302 | |
JacobBramley | 0:f1a93e55feb5 | 303 | set_sda(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 304 | set_sck(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 305 | set_sda(PIN_0); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 306 | set_sck(PIN_0); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 307 | wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 308 | set_sck(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 309 | set_sda(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 310 | set_sck(PIN_0); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 311 | } |
JacobBramley | 0:f1a93e55feb5 | 312 | |
JacobBramley | 0:f1a93e55feb5 | 313 | |
JacobBramley | 0:f1a93e55feb5 | 314 | void SHT7x::put_bit(int b) { |
JacobBramley | 0:f1a93e55feb5 | 315 | uint32_t const t = time_atom(); |
JacobBramley | 0:f1a93e55feb5 | 316 | |
JacobBramley | 0:f1a93e55feb5 | 317 | set_sda(b); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 318 | set_sck(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 319 | wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 320 | set_sck(PIN_0); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 321 | } |
JacobBramley | 0:f1a93e55feb5 | 322 | |
JacobBramley | 0:f1a93e55feb5 | 323 | |
JacobBramley | 0:f1a93e55feb5 | 324 | int SHT7x::get_bit() { |
JacobBramley | 0:f1a93e55feb5 | 325 | uint32_t const t = time_atom(); |
JacobBramley | 0:f1a93e55feb5 | 326 | |
JacobBramley | 0:f1a93e55feb5 | 327 | set_sda(PIN_FREE); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 328 | set_sck(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 329 | int b = sda_; wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 330 | set_sck(PIN_0); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 331 | |
JacobBramley | 0:f1a93e55feb5 | 332 | return b; |
JacobBramley | 0:f1a93e55feb5 | 333 | } |
JacobBramley | 0:f1a93e55feb5 | 334 | |
JacobBramley | 0:f1a93e55feb5 | 335 | |
JacobBramley | 0:f1a93e55feb5 | 336 | // The protocol uses three different ACKs: One input ACK and two output ACKs. A |
JacobBramley | 0:f1a93e55feb5 | 337 | // high output ACK usually ends a transmission. A low output ACK usually |
JacobBramley | 0:f1a93e55feb5 | 338 | // acknowledges a byte as part of a transmission. Refer to the SHT7x datasheet |
JacobBramley | 0:f1a93e55feb5 | 339 | // for details. |
JacobBramley | 0:f1a93e55feb5 | 340 | void SHT7x::put_ack(int b) { |
JacobBramley | 0:f1a93e55feb5 | 341 | uint32_t const t = time_atom(); |
JacobBramley | 0:f1a93e55feb5 | 342 | |
JacobBramley | 0:f1a93e55feb5 | 343 | set_sda(b); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 344 | set_sck(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 345 | wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 346 | set_sck(PIN_0); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 347 | set_sda(PIN_FREE); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 348 | } |
JacobBramley | 0:f1a93e55feb5 | 349 | |
JacobBramley | 0:f1a93e55feb5 | 350 | |
JacobBramley | 0:f1a93e55feb5 | 351 | void SHT7x::get_ack() { |
JacobBramley | 0:f1a93e55feb5 | 352 | uint32_t const t = time_atom(); |
JacobBramley | 0:f1a93e55feb5 | 353 | |
JacobBramley | 0:f1a93e55feb5 | 354 | set_sda(PIN_FREE); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 355 | set_sck(PIN_1); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 356 | wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 357 | set_sck(PIN_0); wait_us(t); |
JacobBramley | 0:f1a93e55feb5 | 358 | } |
JacobBramley | 0:f1a93e55feb5 | 359 | |
JacobBramley | 0:f1a93e55feb5 | 360 | |
JacobBramley | 0:f1a93e55feb5 | 361 | void SHT7x::put_byte(uint32_t byte) { |
JacobBramley | 0:f1a93e55feb5 | 362 | // TODO: Unroll this. |
JacobBramley | 0:f1a93e55feb5 | 363 | for (uint32_t i = 0; i < 8; i++) { |
JacobBramley | 0:f1a93e55feb5 | 364 | put_bit((byte >> (7-i)) & 1); |
JacobBramley | 0:f1a93e55feb5 | 365 | } |
JacobBramley | 0:f1a93e55feb5 | 366 | } |
JacobBramley | 0:f1a93e55feb5 | 367 | |
JacobBramley | 0:f1a93e55feb5 | 368 | |
JacobBramley | 0:f1a93e55feb5 | 369 | uint32_t SHT7x::get_byte() { |
JacobBramley | 0:f1a93e55feb5 | 370 | uint32_t byte = 0; |
JacobBramley | 0:f1a93e55feb5 | 371 | // TODO: Unroll this. |
JacobBramley | 0:f1a93e55feb5 | 372 | for (uint32_t i = 0; i < 8; i++) { |
JacobBramley | 0:f1a93e55feb5 | 373 | byte = (byte << 1) | get_bit(); |
JacobBramley | 0:f1a93e55feb5 | 374 | } |
JacobBramley | 0:f1a93e55feb5 | 375 | return byte; |
JacobBramley | 0:f1a93e55feb5 | 376 | } |
JacobBramley | 0:f1a93e55feb5 | 377 | |
JacobBramley | 0:f1a93e55feb5 | 378 | |
JacobBramley | 0:f1a93e55feb5 | 379 | inline int SHT7x::get_sda() { |
JacobBramley | 0:f1a93e55feb5 | 380 | return sda_.read(); |
JacobBramley | 0:f1a93e55feb5 | 381 | } |
JacobBramley | 0:f1a93e55feb5 | 382 | |
JacobBramley | 0:f1a93e55feb5 | 383 | |
JacobBramley | 0:f1a93e55feb5 | 384 | inline void SHT7x::set_sda(int pin) { |
JacobBramley | 0:f1a93e55feb5 | 385 | set_sda((pin) ? (PIN_1) : (PIN_0)); |
JacobBramley | 0:f1a93e55feb5 | 386 | } |
JacobBramley | 0:f1a93e55feb5 | 387 | |
JacobBramley | 0:f1a93e55feb5 | 388 | |
JacobBramley | 0:f1a93e55feb5 | 389 | inline void SHT7x::set_sda(pin_State pin) { |
JacobBramley | 0:f1a93e55feb5 | 390 | if (sda_state_ != pin) { |
JacobBramley | 0:f1a93e55feb5 | 391 | sda_ = (pin == PIN_0) ? (0) : (1); |
JacobBramley | 0:f1a93e55feb5 | 392 | sda_state_ = pin; |
JacobBramley | 0:f1a93e55feb5 | 393 | } |
JacobBramley | 0:f1a93e55feb5 | 394 | } |
JacobBramley | 0:f1a93e55feb5 | 395 | |
JacobBramley | 0:f1a93e55feb5 | 396 | |
JacobBramley | 0:f1a93e55feb5 | 397 | inline void SHT7x::set_sck(int pin) { |
JacobBramley | 0:f1a93e55feb5 | 398 | set_sck((pin) ? (PIN_1) : (PIN_0)); |
JacobBramley | 0:f1a93e55feb5 | 399 | } |
JacobBramley | 0:f1a93e55feb5 | 400 | |
JacobBramley | 0:f1a93e55feb5 | 401 | |
JacobBramley | 0:f1a93e55feb5 | 402 | inline void SHT7x::set_sck(pin_State pin) { |
JacobBramley | 0:f1a93e55feb5 | 403 | if (sck_state_ != pin) { |
JacobBramley | 0:f1a93e55feb5 | 404 | sck_ = (pin == PIN_0) ? (0) : (1); |
JacobBramley | 0:f1a93e55feb5 | 405 | sck_state_ = pin; |
JacobBramley | 0:f1a93e55feb5 | 406 | } |
JacobBramley | 0:f1a93e55feb5 | 407 | } |
JacobBramley | 0:f1a93e55feb5 | 408 | |
JacobBramley | 0:f1a93e55feb5 | 409 | |
JacobBramley | 0:f1a93e55feb5 | 410 | void SHT7x::reset_comms() { |
JacobBramley | 0:f1a93e55feb5 | 411 | for (uint32_t i = 0; i < 9; i++) { |
JacobBramley | 0:f1a93e55feb5 | 412 | put_bit(1); |
JacobBramley | 0:f1a93e55feb5 | 413 | } |
JacobBramley | 0:f1a93e55feb5 | 414 | } |
JacobBramley | 0:f1a93e55feb5 | 415 | |
JacobBramley | 0:f1a93e55feb5 | 416 | |
JacobBramley | 0:f1a93e55feb5 | 417 | void SHT7x::command(Command command) { |
JacobBramley | 0:f1a93e55feb5 | 418 | start(); |
JacobBramley | 0:f1a93e55feb5 | 419 | put_byte(static_cast<uint32_t>(command)); |
JacobBramley | 0:f1a93e55feb5 | 420 | get_ack(); |
JacobBramley | 0:f1a93e55feb5 | 421 | } |
JacobBramley | 0:f1a93e55feb5 | 422 | |
JacobBramley | 0:f1a93e55feb5 | 423 | |
JacobBramley | 0:f1a93e55feb5 | 424 | bool SHT7x::check_state(State s0) { |
JacobBramley | 0:f1a93e55feb5 | 425 | State state = state_; |
JacobBramley | 0:f1a93e55feb5 | 426 | return state == s0; |
JacobBramley | 0:f1a93e55feb5 | 427 | } |
JacobBramley | 0:f1a93e55feb5 | 428 | |
JacobBramley | 0:f1a93e55feb5 | 429 | |
JacobBramley | 0:f1a93e55feb5 | 430 | bool SHT7x::check_state(State s0, State s1) { |
JacobBramley | 0:f1a93e55feb5 | 431 | State state = state_; |
JacobBramley | 0:f1a93e55feb5 | 432 | return (state == s0) || (state == s1); |
JacobBramley | 0:f1a93e55feb5 | 433 | } |
JacobBramley | 0:f1a93e55feb5 | 434 | |
JacobBramley | 0:f1a93e55feb5 | 435 | |
JacobBramley | 0:f1a93e55feb5 | 436 | bool SHT7x::check_state(State s0, State s1, State s2) { |
JacobBramley | 0:f1a93e55feb5 | 437 | State state = state_; |
JacobBramley | 0:f1a93e55feb5 | 438 | return (state == s0) || (state == s1) || (state == s2); |
JacobBramley | 0:f1a93e55feb5 | 439 | } |
JacobBramley | 0:f1a93e55feb5 | 440 | |
JacobBramley | 0:f1a93e55feb5 | 441 | |
JacobBramley | 0:f1a93e55feb5 | 442 | int SHT7x::payload_size(Command command) { |
JacobBramley | 0:f1a93e55feb5 | 443 | switch (command) { |
JacobBramley | 0:f1a93e55feb5 | 444 | case CMD_READ_TEMP: |
JacobBramley | 0:f1a93e55feb5 | 445 | case CMD_READ_HUM: return 2; |
JacobBramley | 0:f1a93e55feb5 | 446 | case CMD_READ_STATUS: |
JacobBramley | 0:f1a93e55feb5 | 447 | case CMD_WRITE_STATUS: return 1; |
JacobBramley | 0:f1a93e55feb5 | 448 | case CMD_RESET: |
JacobBramley | 0:f1a93e55feb5 | 449 | default: return 0; |
JacobBramley | 0:f1a93e55feb5 | 450 | } |
JacobBramley | 0:f1a93e55feb5 | 451 | } |
JacobBramley | 0:f1a93e55feb5 | 452 | |
JacobBramley | 0:f1a93e55feb5 | 453 | |
JacobBramley | 0:f1a93e55feb5 | 454 | bool SHT7x::check_crc(Command command, uint32_t data, uint32_t crc_in) { |
JacobBramley | 0:f1a93e55feb5 | 455 | int const data_bits = payload_size(command) * 8; |
JacobBramley | 0:f1a93e55feb5 | 456 | int const bits = data_bits + 8; |
JacobBramley | 0:f1a93e55feb5 | 457 | |
JacobBramley | 0:f1a93e55feb5 | 458 | data |= command << data_bits; |
JacobBramley | 0:f1a93e55feb5 | 459 | |
JacobBramley | 0:f1a93e55feb5 | 460 | // The Sensirion application note describes an algorithm which reverses the |
JacobBramley | 0:f1a93e55feb5 | 461 | // bits in the status byte to form the initial CRC, performs the CRC |
JacobBramley | 0:f1a93e55feb5 | 462 | // calculation, then reverses the bits again at the end. This CRC |
JacobBramley | 0:f1a93e55feb5 | 463 | // implementation operates in reverse, so there is no need to reverse the CRC. |
JacobBramley | 0:f1a93e55feb5 | 464 | |
JacobBramley | 0:f1a93e55feb5 | 465 | // TODO: Optimize this further, if possible. |
JacobBramley | 0:f1a93e55feb5 | 466 | |
JacobBramley | 0:f1a93e55feb5 | 467 | // The CRC is initialized with the status byte. |
JacobBramley | 0:f1a93e55feb5 | 468 | uint32_t crc = encode_status_byte(); |
JacobBramley | 0:f1a93e55feb5 | 469 | for (int bit = bits - 1; bit >= 0; bit--) { |
JacobBramley | 0:f1a93e55feb5 | 470 | // Eor bit 0 of the CRC with the top bit of the data to determine the value |
JacobBramley | 0:f1a93e55feb5 | 471 | // to feed back into the CRC. |
JacobBramley | 0:f1a93e55feb5 | 472 | uint32_t result = ((data >> bit) ^ crc) & 1; |
JacobBramley | 0:f1a93e55feb5 | 473 | // Bit 0 contains that value that must be fed back into the CRC at bit |
JacobBramley | 0:f1a93e55feb5 | 474 | // positions 7, 3 and 2, so use it to construct a bit mask. These bits |
JacobBramley | 0:f1a93e55feb5 | 475 | // correspond to positions 0, 4 and 5 in the reversed-CRC implementation. |
JacobBramley | 0:f1a93e55feb5 | 476 | uint32_t invert = (result << 7) | (result << 3) | (result << 2); |
JacobBramley | 0:f1a93e55feb5 | 477 | crc = (crc >> 1) ^ invert; |
JacobBramley | 0:f1a93e55feb5 | 478 | } |
JacobBramley | 0:f1a93e55feb5 | 479 | |
JacobBramley | 0:f1a93e55feb5 | 480 | return crc == crc_in; |
JacobBramley | 0:f1a93e55feb5 | 481 | } |
JacobBramley | 0:f1a93e55feb5 | 482 | |
JacobBramley | 0:f1a93e55feb5 | 483 | |
JacobBramley | 0:f1a93e55feb5 | 484 | // ==== Readings. ==== |
JacobBramley | 0:f1a93e55feb5 | 485 | |
JacobBramley | 0:f1a93e55feb5 | 486 | // Shift 'v' right by 'shift' and perform signed rounding. |
JacobBramley | 0:f1a93e55feb5 | 487 | static inline int64_t shift_round(int64_t v, uint32_t shift) { |
JacobBramley | 0:f1a93e55feb5 | 488 | uint64_t u = static_cast<uint64_t>(v); |
JacobBramley | 0:f1a93e55feb5 | 489 | |
JacobBramley | 0:f1a93e55feb5 | 490 | if (shift == 0) { |
JacobBramley | 0:f1a93e55feb5 | 491 | return v; |
JacobBramley | 0:f1a93e55feb5 | 492 | } |
JacobBramley | 0:f1a93e55feb5 | 493 | |
JacobBramley | 0:f1a93e55feb5 | 494 | // Rounding (with ties away from zero). |
JacobBramley | 0:f1a93e55feb5 | 495 | // Positive: |
JacobBramley | 0:f1a93e55feb5 | 496 | // i += bit(shift-1) |
JacobBramley | 0:f1a93e55feb5 | 497 | // Negative: |
JacobBramley | 0:f1a93e55feb5 | 498 | // i += bit(shift-1) - 1 |
JacobBramley | 0:f1a93e55feb5 | 499 | // We can simply take the value of bit 31 and subtract the value of the |
JacobBramley | 0:f1a93e55feb5 | 500 | // sign bit, then add the result to the truncated reading. |
JacobBramley | 0:f1a93e55feb5 | 501 | // Note that this relies on C99-style division, where negative values are |
JacobBramley | 0:f1a93e55feb5 | 502 | // truncated towards 0. |
JacobBramley | 0:f1a93e55feb5 | 503 | int64_t i = (v / (1LL << shift)); |
JacobBramley | 0:f1a93e55feb5 | 504 | int64_t s = (u >> 63) & 1; |
JacobBramley | 0:f1a93e55feb5 | 505 | int64_t h = (u >> (shift - 1)) & 1; |
JacobBramley | 0:f1a93e55feb5 | 506 | |
JacobBramley | 0:f1a93e55feb5 | 507 | return i + h - s; |
JacobBramley | 0:f1a93e55feb5 | 508 | } |
JacobBramley | 0:f1a93e55feb5 | 509 | |
JacobBramley | 0:f1a93e55feb5 | 510 | |
JacobBramley | 0:f1a93e55feb5 | 511 | // ---- Temperature ---- |
JacobBramley | 0:f1a93e55feb5 | 512 | |
JacobBramley | 0:f1a93e55feb5 | 513 | // -- Floating point. -- |
JacobBramley | 0:f1a93e55feb5 | 514 | |
JacobBramley | 0:f1a93e55feb5 | 515 | float Temp::get_d1_f() const { |
JacobBramley | 0:f1a93e55feb5 | 516 | // The following data-points are provided in the datasheet: |
JacobBramley | 0:f1a93e55feb5 | 517 | // Vdd d1 |
JacobBramley | 0:f1a93e55feb5 | 518 | // 5 -40.1 |
JacobBramley | 0:f1a93e55feb5 | 519 | // 4 -39.8 |
JacobBramley | 0:f1a93e55feb5 | 520 | // 3.5 -39.7 |
JacobBramley | 0:f1a93e55feb5 | 521 | // 3 -39.6 |
JacobBramley | 0:f1a93e55feb5 | 522 | // 2.5 -39.4 |
JacobBramley | 0:f1a93e55feb5 | 523 | // The relationship between Vdd and d1 is not linear. However, the |
JacobBramley | 0:f1a93e55feb5 | 524 | // deviation from a linear relationship is probably a result of aliasing |
JacobBramley | 0:f1a93e55feb5 | 525 | // rather than anything else. The following relationship provides a linear |
JacobBramley | 0:f1a93e55feb5 | 526 | // response that looks like a reasonable best-fit for the specified points: |
JacobBramley | 0:f1a93e55feb5 | 527 | // Vdd d1 |
JacobBramley | 0:f1a93e55feb5 | 528 | // 5 -40.1 |
JacobBramley | 0:f1a93e55feb5 | 529 | // 2.5 -39.43 |
JacobBramley | 0:f1a93e55feb5 | 530 | // |
JacobBramley | 0:f1a93e55feb5 | 531 | // d1 = -0.268 * Vdd - 38.76 |
JacobBramley | 0:f1a93e55feb5 | 532 | return -0.000268 * mvdd - 38.76; |
JacobBramley | 0:f1a93e55feb5 | 533 | } |
JacobBramley | 0:f1a93e55feb5 | 534 | |
JacobBramley | 0:f1a93e55feb5 | 535 | |
JacobBramley | 0:f1a93e55feb5 | 536 | float Temp::get_f() const { |
JacobBramley | 0:f1a93e55feb5 | 537 | float d1 = get_d1_f(); |
JacobBramley | 0:f1a93e55feb5 | 538 | float d2; |
JacobBramley | 0:f1a93e55feb5 | 539 | switch (get_bits()) { |
JacobBramley | 0:f1a93e55feb5 | 540 | case 12: d2 = 0.04f; break; |
JacobBramley | 0:f1a93e55feb5 | 541 | case 14: d2 = 0.01f; break; |
JacobBramley | 0:f1a93e55feb5 | 542 | default: return std::numeric_limits<float>::quiet_NaN(); |
JacobBramley | 0:f1a93e55feb5 | 543 | } |
JacobBramley | 0:f1a93e55feb5 | 544 | return d1 + d2 * get_raw(); |
JacobBramley | 0:f1a93e55feb5 | 545 | } |
JacobBramley | 0:f1a93e55feb5 | 546 | |
JacobBramley | 0:f1a93e55feb5 | 547 | |
JacobBramley | 0:f1a93e55feb5 | 548 | // -- Fixed point. -- |
JacobBramley | 0:f1a93e55feb5 | 549 | |
JacobBramley | 0:f1a93e55feb5 | 550 | int64_t Temp::get_d1_q32() const { |
JacobBramley | 0:f1a93e55feb5 | 551 | // See notes in get_d1_f() for justification of this formula. |
JacobBramley | 0:f1a93e55feb5 | 552 | // d1 = -0.268 * Vdd - 38.76 |
JacobBramley | 0:f1a93e55feb5 | 553 | return -0x0011904bLL * mvdd - 0x26c28f5c28LL; |
JacobBramley | 0:f1a93e55feb5 | 554 | } |
JacobBramley | 0:f1a93e55feb5 | 555 | |
JacobBramley | 0:f1a93e55feb5 | 556 | |
JacobBramley | 0:f1a93e55feb5 | 557 | int64_t Temp::get_q32() const { |
JacobBramley | 0:f1a93e55feb5 | 558 | int64_t d1 = get_d1_q32(); |
JacobBramley | 0:f1a93e55feb5 | 559 | int64_t d2; |
JacobBramley | 0:f1a93e55feb5 | 560 | switch (get_bits()) { |
JacobBramley | 0:f1a93e55feb5 | 561 | case 12: d2 = 0xa3d70a3LL; break; // 0.04, q32 |
JacobBramley | 0:f1a93e55feb5 | 562 | case 14: d2 = 0x28f5c28LL; break; // 0.01, q32 |
JacobBramley | 0:f1a93e55feb5 | 563 | default: return 0; |
JacobBramley | 0:f1a93e55feb5 | 564 | } |
JacobBramley | 0:f1a93e55feb5 | 565 | return d1 + d2 * get_raw(); |
JacobBramley | 0:f1a93e55feb5 | 566 | } |
JacobBramley | 0:f1a93e55feb5 | 567 | |
JacobBramley | 0:f1a93e55feb5 | 568 | |
JacobBramley | 0:f1a93e55feb5 | 569 | int32_t Temp::get_fixed(int fbits) const { |
JacobBramley | 0:f1a93e55feb5 | 570 | return shift_round(get_q32(), 32-fbits); |
JacobBramley | 0:f1a93e55feb5 | 571 | } |
JacobBramley | 0:f1a93e55feb5 | 572 | |
JacobBramley | 0:f1a93e55feb5 | 573 | |
JacobBramley | 0:f1a93e55feb5 | 574 | // ---- Humidity ---- |
JacobBramley | 0:f1a93e55feb5 | 575 | |
JacobBramley | 0:f1a93e55feb5 | 576 | // -- Floating point. -- |
JacobBramley | 0:f1a93e55feb5 | 577 | |
JacobBramley | 0:f1a93e55feb5 | 578 | float Hum::get_f() const { |
JacobBramley | 0:f1a93e55feb5 | 579 | float c1 = -2.0468f; |
JacobBramley | 0:f1a93e55feb5 | 580 | float c2; |
JacobBramley | 0:f1a93e55feb5 | 581 | float c3; |
JacobBramley | 0:f1a93e55feb5 | 582 | float t1 = 0.01f; |
JacobBramley | 0:f1a93e55feb5 | 583 | float t2; |
JacobBramley | 0:f1a93e55feb5 | 584 | float r; |
JacobBramley | 0:f1a93e55feb5 | 585 | float raw = static_cast<float>(get_raw()); |
JacobBramley | 0:f1a93e55feb5 | 586 | switch (get_bits()) { |
JacobBramley | 0:f1a93e55feb5 | 587 | case 8: |
JacobBramley | 0:f1a93e55feb5 | 588 | c2 = 0.5872f; |
JacobBramley | 0:f1a93e55feb5 | 589 | c3 = -4.0845E-4f; |
JacobBramley | 0:f1a93e55feb5 | 590 | t2 = 0.00128f; |
JacobBramley | 0:f1a93e55feb5 | 591 | break; |
JacobBramley | 0:f1a93e55feb5 | 592 | case 12: |
JacobBramley | 0:f1a93e55feb5 | 593 | c2 = 0.0367f; |
JacobBramley | 0:f1a93e55feb5 | 594 | c3 = -1.5955E-6f; |
JacobBramley | 0:f1a93e55feb5 | 595 | t2 = 0.00008f; |
JacobBramley | 0:f1a93e55feb5 | 596 | break; |
JacobBramley | 0:f1a93e55feb5 | 597 | default: |
JacobBramley | 0:f1a93e55feb5 | 598 | return std::numeric_limits<float>::quiet_NaN(); |
JacobBramley | 0:f1a93e55feb5 | 599 | } |
JacobBramley | 0:f1a93e55feb5 | 600 | r = c1 + (c2 * raw) + (c3 * (raw * raw)); |
JacobBramley | 0:f1a93e55feb5 | 601 | if (temp) { |
JacobBramley | 0:f1a93e55feb5 | 602 | r += (temp->get_f() - 25.0f)*(t1+t2*raw); |
JacobBramley | 0:f1a93e55feb5 | 603 | } |
JacobBramley | 0:f1a93e55feb5 | 604 | // Clamp as specified in the datasheet. |
JacobBramley | 0:f1a93e55feb5 | 605 | if (r < 0.0f) { |
JacobBramley | 0:f1a93e55feb5 | 606 | return 0.0f; |
JacobBramley | 0:f1a93e55feb5 | 607 | } |
JacobBramley | 0:f1a93e55feb5 | 608 | if (r > 99.0f) { |
JacobBramley | 0:f1a93e55feb5 | 609 | return 100.0f; |
JacobBramley | 0:f1a93e55feb5 | 610 | } |
JacobBramley | 0:f1a93e55feb5 | 611 | return r; |
JacobBramley | 0:f1a93e55feb5 | 612 | } |
JacobBramley | 0:f1a93e55feb5 | 613 | |
JacobBramley | 0:f1a93e55feb5 | 614 | |
JacobBramley | 0:f1a93e55feb5 | 615 | // -- Fixed point. -- |
JacobBramley | 0:f1a93e55feb5 | 616 | |
JacobBramley | 0:f1a93e55feb5 | 617 | int64_t Hum::get_q32() const { |
JacobBramley | 0:f1a93e55feb5 | 618 | int64_t c1 = -0x20bfb15b5LL; // -2.0468 |
JacobBramley | 0:f1a93e55feb5 | 619 | int64_t c2; |
JacobBramley | 0:f1a93e55feb5 | 620 | int64_t c3; |
JacobBramley | 0:f1a93e55feb5 | 621 | int64_t t1 = 0x28f6LL; // 0.01, q20 |
JacobBramley | 0:f1a93e55feb5 | 622 | int64_t t2; |
JacobBramley | 0:f1a93e55feb5 | 623 | int64_t r; |
JacobBramley | 0:f1a93e55feb5 | 624 | int64_t raw = static_cast<int64_t>(get_raw()); |
JacobBramley | 0:f1a93e55feb5 | 625 | switch (get_bits()) { |
JacobBramley | 0:f1a93e55feb5 | 626 | case 8: |
JacobBramley | 0:f1a93e55feb5 | 627 | c2 = 0x9652bd3cLL; // 0.5872f; |
JacobBramley | 0:f1a93e55feb5 | 628 | c3 = -0x1ac4a7LL; // -4.0845E-4f; |
JacobBramley | 0:f1a93e55feb5 | 629 | t2 = 0x53eLL; // 0.00128f, q20; |
JacobBramley | 0:f1a93e55feb5 | 630 | break; |
JacobBramley | 0:f1a93e55feb5 | 631 | case 12: |
JacobBramley | 0:f1a93e55feb5 | 632 | c2 = 0x9652bd3LL; // 0.0367f; |
JacobBramley | 0:f1a93e55feb5 | 633 | c3 = -0x1ac4LL; // -1.5955E-6f; |
JacobBramley | 0:f1a93e55feb5 | 634 | t2 = 0x54LL; // 0.00008f, q20; |
JacobBramley | 0:f1a93e55feb5 | 635 | break; |
JacobBramley | 0:f1a93e55feb5 | 636 | default: |
JacobBramley | 0:f1a93e55feb5 | 637 | return INT64_MIN; |
JacobBramley | 0:f1a93e55feb5 | 638 | } |
JacobBramley | 0:f1a93e55feb5 | 639 | // The 'c' coefficients are all in q32 format. The raw value is in q0 |
JacobBramley | 0:f1a93e55feb5 | 640 | // (integer) format, so r will be in q32 format after this operation. |
JacobBramley | 0:f1a93e55feb5 | 641 | r = c1 + (c2 * raw) + (c3 * (raw * raw)); |
JacobBramley | 0:f1a93e55feb5 | 642 | if (temp) { |
JacobBramley | 0:f1a93e55feb5 | 643 | int64_t co = t1 + (t2 * raw); // q20 |
JacobBramley | 0:f1a93e55feb5 | 644 | int64_t t = temp->get_q32() - (25LL << 32); |
JacobBramley | 0:f1a93e55feb5 | 645 | r += shift_round(co * t, 20); |
JacobBramley | 0:f1a93e55feb5 | 646 | } |
JacobBramley | 0:f1a93e55feb5 | 647 | // Clamp as specified in the datasheet. |
JacobBramley | 0:f1a93e55feb5 | 648 | if (r < 0LL) { |
JacobBramley | 0:f1a93e55feb5 | 649 | return 0LL; |
JacobBramley | 0:f1a93e55feb5 | 650 | } |
JacobBramley | 0:f1a93e55feb5 | 651 | if (r > (99LL<<32)) { |
JacobBramley | 0:f1a93e55feb5 | 652 | return 100LL<<32; |
JacobBramley | 0:f1a93e55feb5 | 653 | } |
JacobBramley | 0:f1a93e55feb5 | 654 | return r; |
JacobBramley | 0:f1a93e55feb5 | 655 | } |
JacobBramley | 0:f1a93e55feb5 | 656 | |
JacobBramley | 0:f1a93e55feb5 | 657 | |
JacobBramley | 0:f1a93e55feb5 | 658 | int32_t Hum::get_fixed(int fbits) const { |
JacobBramley | 0:f1a93e55feb5 | 659 | return shift_round(get_q32(), 32-fbits); |
JacobBramley | 0:f1a93e55feb5 | 660 | } |
JacobBramley | 0:f1a93e55feb5 | 661 | |
JacobBramley | 0:f1a93e55feb5 | 662 | |
JacobBramley | 0:f1a93e55feb5 | 663 | } // namespace sht7x |