Sam Berjawi / ADS1015

A library for ADS1015 and ADS1115 from Texas Instruments.

Fork of ADS1015 by Arve Seljebu

v1.3 - Added ADS1115_REG_CONFIG_DR & m_dataRate Jul 21. 2014 - Corrected m_conversionDelay - Now there is readADC() that returns counts and readADC_V() that returns voltage

ADS1x15.cpp@2:976073ea60df, 2014-07-22 (annotated)

Committer:
Sambo007
Date:
Tue Jul 22 06:04:13 2014 +0000
Revision:
2:976073ea60df
v1.3	- Added ADS1115_REG_CONFIG_DR & m_dataRate 		- Jul 21. 2014; 	- Corrected m_conversionDelay; 	- Now there is readADC() that returns counts and readADC_V() that returns voltage;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Sambo007 2:976073ea60df 1 /**************************************************************************/
Sambo007 2:976073ea60df 2 /*!
Sambo007 2:976073ea60df 3 @file ADS1x15.cpp
Sambo007 2:976073ea60df 4 @author K.Townsend (Adafruit Industries)
Sambo007 2:976073ea60df 5 @license BSD (see LICENSE.txt)
Sambo007 2:976073ea60df 6
Sambo007 2:976073ea60df 7 Ported to mbed by Arve Seljebu - arve0.github.io
Sambo007 2:976073ea60df 8
Sambo007 2:976073ea60df 9 Driver for the ADS1015/ADS1115 ADC
Sambo007 2:976073ea60df 10
Sambo007 2:976073ea60df 11 This is a library for the Adafruit MPL115A2 breakout
Sambo007 2:976073ea60df 12 ----> https://www.adafruit.com/products/1083
Sambo007 2:976073ea60df 13
Sambo007 2:976073ea60df 14 Adafruit invests time and resources providing this open source code,
Sambo007 2:976073ea60df 15 please support Adafruit and open-source hardware by purchasing
Sambo007 2:976073ea60df 16 products from Adafruit!
Sambo007 2:976073ea60df 17
Sambo007 2:976073ea60df 18 @section HISTORY
Sambo007 2:976073ea60df 19
Sambo007 2:976073ea60df 20 v1.0 - First release
Sambo007 2:976073ea60df 21 v1.1 - Added ADS1115 support - W. Earl
Sambo007 2:976073ea60df 22 v1.1.1 - Ported to mbed - Arve Seljebu
Sambo007 2:976073ea60df 23 v1.2 - Fixed error in readADC_SingleEnded() sign bit - Sam Berjawi
Sambo007 2:976073ea60df 24 v1.3 - Added ADS1115_REG_CONFIG_DR & m_dataRate - Sam W Berjawi Jul 21. 2014
Sambo007 2:976073ea60df 25 - Corrected m_conversionDelay
Sambo007 2:976073ea60df 26 - Now there is readADC() that returns counts and readADC_V() that returns voltage
Sambo007 2:976073ea60df 27 */
Sambo007 2:976073ea60df 28 /**************************************************************************/
Sambo007 2:976073ea60df 29
Sambo007 2:976073ea60df 30 #include "ADS1x15.h"
Sambo007 2:976073ea60df 31
Sambo007 2:976073ea60df 32 /**************************************************************************/
Sambo007 2:976073ea60df 33 /*!
Sambo007 2:976073ea60df 34 @brief Writes 16-bits to the specified destination register
Sambo007 2:976073ea60df 35 */
Sambo007 2:976073ea60df 36 /**************************************************************************/
Sambo007 2:976073ea60df 37 void ADS1015::writeRegister(uint8_t i2cAddress, uint8_t reg, uint16_t value) {
Sambo007 2:976073ea60df 38 char cmd[3];
Sambo007 2:976073ea60df 39 cmd[0] = (char)reg;
Sambo007 2:976073ea60df 40 cmd[1] = (char)(value>>8);
Sambo007 2:976073ea60df 41 cmd[2] = (char)(value & 0xFF);
Sambo007 2:976073ea60df 42 m_i2c->write(i2cAddress, cmd, 3);
Sambo007 2:976073ea60df 43 }
Sambo007 2:976073ea60df 44
Sambo007 2:976073ea60df 45 /**************************************************************************/
Sambo007 2:976073ea60df 46 /*!
Sambo007 2:976073ea60df 47 @brief Reads 16-bits from the specified register
Sambo007 2:976073ea60df 48 */
Sambo007 2:976073ea60df 49 /**************************************************************************/
Sambo007 2:976073ea60df 50 uint16_t ADS1015::readRegister(uint8_t i2cAddress, uint8_t reg) {
Sambo007 2:976073ea60df 51 char data[2];
Sambo007 2:976073ea60df 52 data[0] = reg; // temporary use this to send address to conversion register
Sambo007 2:976073ea60df 53 m_i2c->write(i2cAddress, data, 1);
Sambo007 2:976073ea60df 54 m_i2c->read(i2cAddress, data, 2);
Sambo007 2:976073ea60df 55 return (data[0] << 8 | data [1]);
Sambo007 2:976073ea60df 56 }
Sambo007 2:976073ea60df 57
Sambo007 2:976073ea60df 58 /**************************************************************************/
Sambo007 2:976073ea60df 59 /*!
Sambo007 2:976073ea60df 60 @brief Instantiates a new ADS1015 class w/appropriate properties
Sambo007 2:976073ea60df 61 */
Sambo007 2:976073ea60df 62 /**************************************************************************/
Sambo007 2:976073ea60df 63 ADS1015::ADS1015(I2C* i2c, uint8_t i2cAddress)
Sambo007 2:976073ea60df 64 {
Sambo007 2:976073ea60df 65 // shift 7 bit address 1 left: read expects 8 bit address, see I2C.h
Sambo007 2:976073ea60df 66 m_i2cAddress = i2cAddress << 1;
Sambo007 2:976073ea60df 67 m_bitShift = 4;
Sambo007 2:976073ea60df 68 m_i2c = i2c;
Sambo007 2:976073ea60df 69 }
Sambo007 2:976073ea60df 70
Sambo007 2:976073ea60df 71 /**************************************************************************/
Sambo007 2:976073ea60df 72 /*!
Sambo007 2:976073ea60df 73 @brief Instantiates a new ADS1115 class w/appropriate properties
Sambo007 2:976073ea60df 74 */
Sambo007 2:976073ea60df 75 /**************************************************************************/
Sambo007 2:976073ea60df 76 ADS1115::ADS1115(I2C* i2c, uint8_t i2cAddress)
Sambo007 2:976073ea60df 77 {
Sambo007 2:976073ea60df 78 // shift 7 bit address 1 left: read expects 8 bit address, see mbed's I2C.h
Sambo007 2:976073ea60df 79 m_i2cAddress = i2cAddress << 1;
Sambo007 2:976073ea60df 80 m_bitShift = 0;
Sambo007 2:976073ea60df 81 m_i2c = i2c;
Sambo007 2:976073ea60df 82 }
Sambo007 2:976073ea60df 83
Sambo007 2:976073ea60df 84 /**************************************************************************/
Sambo007 2:976073ea60df 85 /*!
Sambo007 2:976073ea60df 86 @brief Reads the A2D conversion result, measuring depending on chan parameter either
Sambo007 2:976073ea60df 87 the single chan voltage or the differential voltage between the P (AIN_i) and N (AIN_j) inputs.
Sambo007 2:976073ea60df 88 Generates a signed value since the difference can be either positive or negative.
Sambo007 2:976073ea60df 89
Sambo007 2:976073ea60df 90 The +/-6.144V and +/-4.096V settings express the full-scale range of the ADC scaling.
Sambo007 2:976073ea60df 91 In no event should more than VDD + 0.3V be applied to this device
Sambo007 2:976073ea60df 92
Sambo007 2:976073ea60df 93 @return Count
Sambo007 2:976073ea60df 94 */
Sambo007 2:976073ea60df 95 /**************************************************************************/
Sambo007 2:976073ea60df 96 int16_t ADS1015::readADC(chan_t chan, adsVR_t voltageRange, adsDR_t dataRate)
Sambo007 2:976073ea60df 97 {
Sambo007 2:976073ea60df 98 // Prepare Config Register
Sambo007 2:976073ea60df 99 uint16_t config = ADS1015_REG_CONFIG_OS_SINGLE | // Begin a single conversion (when in power-down mode)
Sambo007 2:976073ea60df 100 ADS1015_REG_CONFIG_CQUE_NONE | // Disable the comparator (default val)
Sambo007 2:976073ea60df 101 ADS1015_REG_CONFIG_CLAT_NONLAT | // Non-latching (default val)
Sambo007 2:976073ea60df 102 ADS1015_REG_CONFIG_CPOL_ACTVLOW | // Alert/Rdy active low (default val)
Sambo007 2:976073ea60df 103 ADS1015_REG_CONFIG_CMODE_TRAD | // Traditional comparator (default val)
Sambo007 2:976073ea60df 104 ADS1015_REG_CONFIG_MODE_SINGLE; // Single-shot mode (default)
Sambo007 2:976073ea60df 105
Sambo007 2:976073ea60df 106 // Set channel(s)
Sambo007 2:976073ea60df 107 config |= chan;
Sambo007 2:976073ea60df 108
Sambo007 2:976073ea60df 109 // Set PGA/voltage range
Sambo007 2:976073ea60df 110 config |= voltageRange;
Sambo007 2:976073ea60df 111
Sambo007 2:976073ea60df 112 // Set Data rate
Sambo007 2:976073ea60df 113 config |= dataRate;
Sambo007 2:976073ea60df 114
Sambo007 2:976073ea60df 115 // Write config register to the ADC
Sambo007 2:976073ea60df 116 writeRegister(m_i2cAddress, ADS1015_REG_POINTER_CONFIG, config);
Sambo007 2:976073ea60df 117
Sambo007 2:976073ea60df 118 // TODO: Modify to alternatively use the RDY (EOC) pin instead of waiting. Maybe also use interrupt and continuous mode
Sambo007 2:976073ea60df 119
Sambo007 2:976073ea60df 120 if (m_bitShift == 4) // ADS1015
Sambo007 2:976073ea60df 121 switch (dataRate) {
Sambo007 2:976073ea60df 122 case ADS1015_DR_128SPS:
Sambo007 2:976073ea60df 123 m_conversionDelay = 1.0 / 128;
Sambo007 2:976073ea60df 124 break;
Sambo007 2:976073ea60df 125 case ADS1015_DR_250SPS:
Sambo007 2:976073ea60df 126 m_conversionDelay = 1.0 / 250;
Sambo007 2:976073ea60df 127 break;
Sambo007 2:976073ea60df 128 case ADS1015_DR_490SPS:
Sambo007 2:976073ea60df 129 m_conversionDelay = 1.0 / 490;
Sambo007 2:976073ea60df 130 break;
Sambo007 2:976073ea60df 131 case ADS1015_DR_920SPS:
Sambo007 2:976073ea60df 132 m_conversionDelay = 1.0 / 920;
Sambo007 2:976073ea60df 133 break;
Sambo007 2:976073ea60df 134 case ADS1015_DR_1600SPS:
Sambo007 2:976073ea60df 135 m_conversionDelay = 1.0 / 1600;
Sambo007 2:976073ea60df 136 break;
Sambo007 2:976073ea60df 137 case ADS1015_DR_2400SPS:
Sambo007 2:976073ea60df 138 m_conversionDelay = 1.0 / 2400;
Sambo007 2:976073ea60df 139 break;
Sambo007 2:976073ea60df 140 case ADS1015_DR_3300SPS:
Sambo007 2:976073ea60df 141 m_conversionDelay = 1.0 / 3300;
Sambo007 2:976073ea60df 142 break;
Sambo007 2:976073ea60df 143 }
Sambo007 2:976073ea60df 144 else // ADS1115
Sambo007 2:976073ea60df 145 switch (dataRate) {
Sambo007 2:976073ea60df 146 case ADS1115_DR_8SPS:
Sambo007 2:976073ea60df 147 m_conversionDelay = 1.0 / 8;
Sambo007 2:976073ea60df 148 break;
Sambo007 2:976073ea60df 149 case ADS1115_DR_16SPS:
Sambo007 2:976073ea60df 150 m_conversionDelay = 1.0 / 16;
Sambo007 2:976073ea60df 151 break;
Sambo007 2:976073ea60df 152 case ADS1115_DR_32SPS:
Sambo007 2:976073ea60df 153 m_conversionDelay = 1.0 / 32;
Sambo007 2:976073ea60df 154 break;
Sambo007 2:976073ea60df 155 case ADS1115_DR_64SPS:
Sambo007 2:976073ea60df 156 m_conversionDelay = 1.0 / 64;
Sambo007 2:976073ea60df 157 break;
Sambo007 2:976073ea60df 158 case ADS1115_DR_128SPS:
Sambo007 2:976073ea60df 159 m_conversionDelay = 1.0 / 128;
Sambo007 2:976073ea60df 160 break;
Sambo007 2:976073ea60df 161 case ADS1115_DR_250SPS:
Sambo007 2:976073ea60df 162 m_conversionDelay = 1.0 / 250;
Sambo007 2:976073ea60df 163 break;
Sambo007 2:976073ea60df 164 case ADS1115_DR_475SPS:
Sambo007 2:976073ea60df 165 m_conversionDelay = 1.0 / 475;
Sambo007 2:976073ea60df 166 break;
Sambo007 2:976073ea60df 167 case ADS1115_DR_860SPS:
Sambo007 2:976073ea60df 168 m_conversionDelay = 1.0 / 860;
Sambo007 2:976073ea60df 169 break;
Sambo007 2:976073ea60df 170 }
Sambo007 2:976073ea60df 171
Sambo007 2:976073ea60df 172 // Wait for the conversion to complete
Sambo007 2:976073ea60df 173 wait(m_conversionDelay);
Sambo007 2:976073ea60df 174
Sambo007 2:976073ea60df 175 // Read the conversion results
Sambo007 2:976073ea60df 176 uint16_t res = readRegister(m_i2cAddress, ADS1015_REG_POINTER_CONVERT) >> m_bitShift;
Sambo007 2:976073ea60df 177 if (m_bitShift == 0)
Sambo007 2:976073ea60df 178 {
Sambo007 2:976073ea60df 179 return (int16_t)res;
Sambo007 2:976073ea60df 180 }
Sambo007 2:976073ea60df 181 else
Sambo007 2:976073ea60df 182 {
Sambo007 2:976073ea60df 183 // Shift 12-bit results right 4 bits for the ADS1015,
Sambo007 2:976073ea60df 184 // making sure we keep the sign bit intact
Sambo007 2:976073ea60df 185 if (res > 0x07FF)
Sambo007 2:976073ea60df 186 {
Sambo007 2:976073ea60df 187 // negative number - extend the sign to 16th bit
Sambo007 2:976073ea60df 188 res |= 0xF000;
Sambo007 2:976073ea60df 189 }
Sambo007 2:976073ea60df 190 return (int16_t)res;
Sambo007 2:976073ea60df 191 }
Sambo007 2:976073ea60df 192 }
Sambo007 2:976073ea60df 193
Sambo007 2:976073ea60df 194 /**************************************************************************/
Sambo007 2:976073ea60df 195 /*!
Sambo007 2:976073ea60df 196 @brief Reads the A2D conversion result, measuring depending on chan parameter either
Sambo007 2:976073ea60df 197 the single chan voltage or the differential voltage between the P (AIN_i) and N (AIN_j) inputs.
Sambo007 2:976073ea60df 198 Generates a signed value since the difference can be either positive or negative.
Sambo007 2:976073ea60df 199
Sambo007 2:976073ea60df 200 The +/-6.144V and +/-4.096V settings express the full-scale range of the ADC scaling.
Sambo007 2:976073ea60df 201 In no event should more than VDD + 0.3V be applied to this device
Sambo007 2:976073ea60df 202
Sambo007 2:976073ea60df 203 @return Voltage
Sambo007 2:976073ea60df 204 */
Sambo007 2:976073ea60df 205 /**************************************************************************/
Sambo007 2:976073ea60df 206 float ADS1015::readADC_V(chan_t chan, adsVR_t voltageRange, adsDR_t dataRate)
Sambo007 2:976073ea60df 207 {
Sambo007 2:976073ea60df 208 float bit_V = 0.;
Sambo007 2:976073ea60df 209
Sambo007 2:976073ea60df 210 // ADS1015 ADS1115
Sambo007 2:976073ea60df 211 // +/-6.144V range = Gain 2/3 1-bit = 3mV 0.1875mV
Sambo007 2:976073ea60df 212 // +/-4.096V range = Gain 1 1-bit = 2mV 0.125mV
Sambo007 2:976073ea60df 213 // +/-2.048V range = Gain 2 1-bit = 1mV 0.0625mV
Sambo007 2:976073ea60df 214 // +/-1.024V range = Gain 4 1-bit = 0.5mV 0.03125mV
Sambo007 2:976073ea60df 215 // +/-0.512V range = Gain 8 1-bit = 0.25mV 0.015625mV
Sambo007 2:976073ea60df 216 // +/-0.256V range = Gain 16 1-bit = 0.125mV 0.0078125mV
Sambo007 2:976073ea60df 217
Sambo007 2:976073ea60df 218 switch (voltageRange) {
Sambo007 2:976073ea60df 219 case VR_p_m_6_144V:
Sambo007 2:976073ea60df 220 bit_V = 3.0e-3f * powf(2, -4 + m_bitShift);
Sambo007 2:976073ea60df 221 break;
Sambo007 2:976073ea60df 222 case VR_p_m_4_096V:
Sambo007 2:976073ea60df 223 bit_V = 2.0e-3f * powf(2, -4 + m_bitShift);
Sambo007 2:976073ea60df 224 break;
Sambo007 2:976073ea60df 225 case VR_p_m_2_048V:
Sambo007 2:976073ea60df 226 bit_V = 1.0e-3f * powf(2, -4 + m_bitShift);
Sambo007 2:976073ea60df 227 break;
Sambo007 2:976073ea60df 228 case VR_p_m_1_024V:
Sambo007 2:976073ea60df 229 bit_V = 0.5e-3f * powf(2, -4 + m_bitShift);
Sambo007 2:976073ea60df 230 break;
Sambo007 2:976073ea60df 231 case VR_p_m_0_512V:
Sambo007 2:976073ea60df 232 bit_V = 0.25e-3f * powf(2, -4 + m_bitShift);
Sambo007 2:976073ea60df 233 break;
Sambo007 2:976073ea60df 234 case VR_p_m_0_256V:
Sambo007 2:976073ea60df 235 bit_V = 0.125e-3f * powf(2, -4 + m_bitShift);
Sambo007 2:976073ea60df 236 break;
Sambo007 2:976073ea60df 237 }
Sambo007 2:976073ea60df 238
Sambo007 2:976073ea60df 239 return (readADC(chan, voltageRange, dataRate) * bit_V);
Sambo007 2:976073ea60df 240 }
Sambo007 2:976073ea60df 241
Sambo007 2:976073ea60df 242 /**************************************************************************/
Sambo007 2:976073ea60df 243 /*!
Sambo007 2:976073ea60df 244 @brief Sets up the comparator to operate in basic mode, causing the
Sambo007 2:976073ea60df 245 ALERT/RDY pin to assert (go from high to low) when the ADC
Sambo007 2:976073ea60df 246 value exceeds the specified threshold.
Sambo007 2:976073ea60df 247
Sambo007 2:976073ea60df 248 This will also set the ADC in continuous conversion mode.
Sambo007 2:976073ea60df 249 */
Sambo007 2:976073ea60df 250 /**************************************************************************/
Sambo007 2:976073ea60df 251 void ADS1015::startComparator_SingleEnded(chan_t chan, adsVR_t voltageRange, adsDR_t dataRate, int16_t threshold)
Sambo007 2:976073ea60df 252 {
Sambo007 2:976073ea60df 253 // Prepare Config Register
Sambo007 2:976073ea60df 254 uint16_t config = ADS1015_REG_CONFIG_CQUE_1CONV | // Comparator enabled and asserts on 1 match
Sambo007 2:976073ea60df 255 ADS1015_REG_CONFIG_CLAT_LATCH | // Latching mode
Sambo007 2:976073ea60df 256 ADS1015_REG_CONFIG_CPOL_ACTVLOW | // Alert/Rdy active low (default val)
Sambo007 2:976073ea60df 257 ADS1015_REG_CONFIG_CMODE_TRAD | // Traditional comparator (default val)
Sambo007 2:976073ea60df 258 ADS1015_REG_CONFIG_MODE_SINGLE; // Single-shot mode (default)
Sambo007 2:976073ea60df 259
Sambo007 2:976073ea60df 260 // Set channel(s)
Sambo007 2:976073ea60df 261 config |= chan;
Sambo007 2:976073ea60df 262
Sambo007 2:976073ea60df 263 // Set PGA/voltage range
Sambo007 2:976073ea60df 264 config |= voltageRange;
Sambo007 2:976073ea60df 265
Sambo007 2:976073ea60df 266 // Set Data rate
Sambo007 2:976073ea60df 267 config |= dataRate;
Sambo007 2:976073ea60df 268
Sambo007 2:976073ea60df 269 // Set the high threshold register
Sambo007 2:976073ea60df 270 // Shift 12-bit results left 4 bits for the ADS1015
Sambo007 2:976073ea60df 271 writeRegister(m_i2cAddress, ADS1015_REG_POINTER_HITHRESH, threshold << m_bitShift);
Sambo007 2:976073ea60df 272
Sambo007 2:976073ea60df 273 // Write config register to the ADC
Sambo007 2:976073ea60df 274 writeRegister(m_i2cAddress, ADS1015_REG_POINTER_CONFIG, config);
Sambo007 2:976073ea60df 275 }
Sambo007 2:976073ea60df 276
Sambo007 2:976073ea60df 277 /**************************************************************************/
Sambo007 2:976073ea60df 278 /*!
Sambo007 2:976073ea60df 279 @brief In order to clear the comparator, we need to read the
Sambo007 2:976073ea60df 280 conversion results. This function reads the last conversion
Sambo007 2:976073ea60df 281 results without changing the config value.
Sambo007 2:976073ea60df 282 */
Sambo007 2:976073ea60df 283 /**************************************************************************/
Sambo007 2:976073ea60df 284 int16_t ADS1015::getLastConversionResults()
Sambo007 2:976073ea60df 285 {
Sambo007 2:976073ea60df 286 // Wait for the conversion to complete
Sambo007 2:976073ea60df 287 wait_ms(m_conversionDelay);
Sambo007 2:976073ea60df 288
Sambo007 2:976073ea60df 289 // Read the conversion results
Sambo007 2:976073ea60df 290 uint16_t res = readRegister(m_i2cAddress, ADS1015_REG_POINTER_CONVERT) >> m_bitShift;
Sambo007 2:976073ea60df 291 if (m_bitShift == 0)
Sambo007 2:976073ea60df 292 {
Sambo007 2:976073ea60df 293 return (int16_t)res;
Sambo007 2:976073ea60df 294 }
Sambo007 2:976073ea60df 295 else
Sambo007 2:976073ea60df 296 {
Sambo007 2:976073ea60df 297 // Shift 12-bit results right 4 bits for the ADS1015,
Sambo007 2:976073ea60df 298 // making sure we keep the sign bit intact
Sambo007 2:976073ea60df 299 if (res > 0x07FF)
Sambo007 2:976073ea60df 300 {
Sambo007 2:976073ea60df 301 // negative number - extend the sign to 16th bit
Sambo007 2:976073ea60df 302 res |= 0xF000;
Sambo007 2:976073ea60df 303 }
Sambo007 2:976073ea60df 304 return (int16_t)res;
Sambo007 2:976073ea60df 305 }
Sambo007 2:976073ea60df 306 }