Analog Devices / mbed-drivers

A collection of Analog Devices drivers for the mbed platform

For additional information check out the mbed page of the Analog Devices wiki: https://wiki.analog.com/resources/tools-software/mbed-drivers-all

libraries/ad7791/AD7791.cpp@17:b8356808e8ad, 2016-04-29 (annotated)

Committer:
Adrian Suciu
Date:
Fri Apr 29 17:34:07 2016 +0300
Revision:
17:b8356808e8ad
Parent:
16:b8a49ec95bad
Child:
20:9790e53d6e26
Fixed code style and added doxygen tags

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Adrian Suciu 13:66c8e4ce4ff1 1 /**
Adrian Suciu 13:66c8e4ce4ff1 2 * @file AD7791.cpp
Adrian Suciu 13:66c8e4ce4ff1 3 * @brief Source file for AD7791 ADC
Adrian Suciu 13:66c8e4ce4ff1 4 * @author Analog Devices Inc.
Adrian Suciu 13:66c8e4ce4ff1 5 *
Adrian Suciu 13:66c8e4ce4ff1 6 * For support please go to:
Adrian Suciu 13:66c8e4ce4ff1 7 * Github: https://github.com/analogdevicesinc/mbed-adi
Adrian Suciu 13:66c8e4ce4ff1 8 * Support: https://ez.analog.com/community/linux-device-drivers/microcontroller-no-os-drivers
Adrian Suciu 13:66c8e4ce4ff1 9 * Product: http://www.analog.com/ad7791
Adrian Suciu 13:66c8e4ce4ff1 10 * More: https://wiki.analog.com/resources/tools-software/mbed-drivers-all
Adrian Suciu 13:66c8e4ce4ff1 11
Adrian Suciu 13:66c8e4ce4ff1 12 ********************************************************************************
Adrian Suciu 13:66c8e4ce4ff1 13 * Copyright 2016(c) Analog Devices, Inc.
Adrian Suciu 13:66c8e4ce4ff1 14 *
Adrian Suciu 13:66c8e4ce4ff1 15 * All rights reserved.
Adrian Suciu 13:66c8e4ce4ff1 16 *
Adrian Suciu 13:66c8e4ce4ff1 17 * Redistribution and use in source and binary forms, with or without
Adrian Suciu 13:66c8e4ce4ff1 18 * modification, are permitted provided that the following conditions are met:
Adrian Suciu 13:66c8e4ce4ff1 19 * - Redistributions of source code must retain the above copyright
Adrian Suciu 13:66c8e4ce4ff1 20 * notice, this list of conditions and the following disclaimer.
Adrian Suciu 13:66c8e4ce4ff1 21 * - Redistributions in binary form must reproduce the above copyright
Adrian Suciu 13:66c8e4ce4ff1 22 * notice, this list of conditions and the following disclaimer in
Adrian Suciu 13:66c8e4ce4ff1 23 * the documentation and/or other materials provided with the
Adrian Suciu 13:66c8e4ce4ff1 24 * distribution.
Adrian Suciu 13:66c8e4ce4ff1 25 * - Neither the name of Analog Devices, Inc. nor the names of its
Adrian Suciu 13:66c8e4ce4ff1 26 * contributors may be used to endorse or promote products derived
Adrian Suciu 13:66c8e4ce4ff1 27 * from this software without specific prior written permission.
Adrian Suciu 13:66c8e4ce4ff1 28 * - The use of this software may or may not infringe the patent rights
Adrian Suciu 13:66c8e4ce4ff1 29 * of one or more patent holders. This license does not release you
Adrian Suciu 13:66c8e4ce4ff1 30 * from the requirement that you obtain separate licenses from these
Adrian Suciu 13:66c8e4ce4ff1 31 * patent holders to use this software.
Adrian Suciu 13:66c8e4ce4ff1 32 * - Use of the software either in source or binary form, must be run
Adrian Suciu 13:66c8e4ce4ff1 33 * on or directly connected to an Analog Devices Inc. component.
Adrian Suciu 13:66c8e4ce4ff1 34 *
Adrian Suciu 13:66c8e4ce4ff1 35 * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
Adrian Suciu 13:66c8e4ce4ff1 36 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
Adrian Suciu 13:66c8e4ce4ff1 37 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
Adrian Suciu 13:66c8e4ce4ff1 38 * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
Adrian Suciu 13:66c8e4ce4ff1 39 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
Adrian Suciu 13:66c8e4ce4ff1 40 * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
Adrian Suciu 13:66c8e4ce4ff1 41 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
Adrian Suciu 13:66c8e4ce4ff1 42 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
Adrian Suciu 13:66c8e4ce4ff1 43 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
Adrian Suciu 13:66c8e4ce4ff1 44 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Adrian Suciu 13:66c8e4ce4ff1 45 *
Adrian Suciu 13:66c8e4ce4ff1 46 ********************************************************************************/
Adrian Suciu 13:66c8e4ce4ff1 47
Adrian Suciu 13:66c8e4ce4ff1 48 #include <stdint.h>
Adrian Suciu 13:66c8e4ce4ff1 49 #include "mbed.h"
Adrian Suciu 13:66c8e4ce4ff1 50 #include "AD7791.h"
Adrian Suciu 13:66c8e4ce4ff1 51
Adrian Suciu 13:66c8e4ce4ff1 52 /**
Adrian Suciu 13:66c8e4ce4ff1 53 * @brief AD7791 constructor, sets CS pin and SPI format
Adrian Suciu 13:66c8e4ce4ff1 54 * @param CS - (optional)chip select of the AD7791
Adrian Suciu 13:66c8e4ce4ff1 55 * @param MOSI - (optional)pin of the SPI interface
Adrian Suciu 13:66c8e4ce4ff1 56 * @param MISO - (optional)pin of the SPI interface
Adrian Suciu 13:66c8e4ce4ff1 57 * @param SCK - (optional)pin of the SPI interface
Adrian Suciu 13:66c8e4ce4ff1 58 */
Adrian Suciu 13:66c8e4ce4ff1 59 AD7791::AD7791(float reference_voltage,
Adrian Suciu 13:66c8e4ce4ff1 60 PinName CS,
Adrian Suciu 13:66c8e4ce4ff1 61 PinName MOSI,
Adrian Suciu 13:66c8e4ce4ff1 62 PinName MISO,
Adrian Suciu 13:66c8e4ce4ff1 63 PinName SCK) :
Adrian Suciu 17:b8356808e8ad 64 miso(MISO), ad7791(MOSI, MISO, SCK), cs(CS), _vref(reference_voltage)
Adrian Suciu 13:66c8e4ce4ff1 65 {
Adrian Suciu 13:66c8e4ce4ff1 66 cs = true; // cs is active low
Adrian Suciu 13:66c8e4ce4ff1 67 ad7791.format(8, _SPI_MODE);
Adrian Suciu 13:66c8e4ce4ff1 68 _continous_conversion = true;
Adrian Suciu 13:66c8e4ce4ff1 69 _channel = DIFFERENTIAL;
Adrian Suciu 13:66c8e4ce4ff1 70 }
Adrian Suciu 13:66c8e4ce4ff1 71
Adrian Suciu 13:66c8e4ce4ff1 72 /**
Adrian Suciu 13:66c8e4ce4ff1 73 * @brief Set AD7791 SPI frequency
Adrian Suciu 13:66c8e4ce4ff1 74 * @param hz - SPI bus frequency in hz
Adrian Suciu 13:66c8e4ce4ff1 75 * @return none
Adrian Suciu 13:66c8e4ce4ff1 76 */
Adrian Suciu 13:66c8e4ce4ff1 77 void AD7791::frequency(int hz)
Adrian Suciu 13:66c8e4ce4ff1 78 {
Adrian Suciu 13:66c8e4ce4ff1 79 ad7791.frequency(hz);
Adrian Suciu 13:66c8e4ce4ff1 80 }
Adrian Suciu 13:66c8e4ce4ff1 81
Adrian Suciu 13:66c8e4ce4ff1 82 /**
Adrian Suciu 13:66c8e4ce4ff1 83 * @brief Resets the AD7791
Adrian Suciu 13:66c8e4ce4ff1 84 * @return none
Adrian Suciu 13:66c8e4ce4ff1 85 */
Adrian Suciu 13:66c8e4ce4ff1 86 void AD7791::reset()
Adrian Suciu 13:66c8e4ce4ff1 87 {
Adrian Suciu 13:66c8e4ce4ff1 88 ad7791.format(8, _SPI_MODE);
Adrian Suciu 13:66c8e4ce4ff1 89 cs = false;
Adrian Suciu 13:66c8e4ce4ff1 90 wait_us(_DELAY_TIMING);
Adrian Suciu 13:66c8e4ce4ff1 91 ad7791.write(_RESET);
Adrian Suciu 13:66c8e4ce4ff1 92 ad7791.write(_RESET);
Adrian Suciu 13:66c8e4ce4ff1 93 ad7791.write(_RESET);
Adrian Suciu 13:66c8e4ce4ff1 94 ad7791.write(_RESET);
Adrian Suciu 13:66c8e4ce4ff1 95 wait_us(_DELAY_TIMING);
Adrian Suciu 13:66c8e4ce4ff1 96 cs = true;
Adrian Suciu 13:66c8e4ce4ff1 97 _continous_conversion = true;
Adrian Suciu 13:66c8e4ce4ff1 98 }
Adrian Suciu 13:66c8e4ce4ff1 99
Adrian Suciu 13:66c8e4ce4ff1 100 /**
Adrian Suciu 13:66c8e4ce4ff1 101 * Sets the mode register. Also sets continous mode and range based on the value
Adrian Suciu 13:66c8e4ce4ff1 102 * written in reg_val
Adrian Suciu 13:66c8e4ce4ff1 103 * @param reg_val
Adrian Suciu 13:66c8e4ce4ff1 104 */
Adrian Suciu 13:66c8e4ce4ff1 105 void AD7791::write_mode_reg(uint8_t reg_val)
Adrian Suciu 13:66c8e4ce4ff1 106 {
Adrian Suciu 13:66c8e4ce4ff1 107 write_reg(MODE_REG, reg_val);
Adrian Suciu 13:66c8e4ce4ff1 108 uint8_t continous_mode = (reg_val & 0xC0);
Adrian Suciu 13:66c8e4ce4ff1 109 if(continous_mode == 0x00) {
Adrian Suciu 13:66c8e4ce4ff1 110 _continous_conversion = true;
Adrian Suciu 13:66c8e4ce4ff1 111 } else {
Adrian Suciu 13:66c8e4ce4ff1 112 _continous_conversion = false;
Adrian Suciu 13:66c8e4ce4ff1 113 }
Adrian Suciu 17:b8356808e8ad 114 /* uint8_t range = (reg_val & 0x30);
Adrian Suciu 17:b8356808e8ad 115 _PGA_gain = 1 << (range >> 4);*/
Adrian Suciu 13:66c8e4ce4ff1 116
Adrian Suciu 13:66c8e4ce4ff1 117 }
Adrian Suciu 13:66c8e4ce4ff1 118
Adrian Suciu 13:66c8e4ce4ff1 119 /**
Adrian Suciu 13:66c8e4ce4ff1 120 * Reads the mode register and returns its value
Adrian Suciu 13:66c8e4ce4ff1 121 * @return value of the mode register
Adrian Suciu 13:66c8e4ce4ff1 122 */
Adrian Suciu 13:66c8e4ce4ff1 123 uint8_t AD7791::read_mode_reg()
Adrian Suciu 13:66c8e4ce4ff1 124 {
Adrian Suciu 13:66c8e4ce4ff1 125 return read_reg(MODE_REG);
Adrian Suciu 13:66c8e4ce4ff1 126 }
Adrian Suciu 13:66c8e4ce4ff1 127
Adrian Suciu 13:66c8e4ce4ff1 128 /**
Adrian Suciu 13:66c8e4ce4ff1 129 * Writes the filter register
Adrian Suciu 13:66c8e4ce4ff1 130 * @param regValue value to be written.
Adrian Suciu 13:66c8e4ce4ff1 131 */
Adrian Suciu 13:66c8e4ce4ff1 132 void AD7791::write_filter_reg(uint8_t reg_val)
Adrian Suciu 13:66c8e4ce4ff1 133 {
Adrian Suciu 13:66c8e4ce4ff1 134 write_reg(FILTER_REG, reg_val);
Adrian Suciu 13:66c8e4ce4ff1 135 }
Adrian Suciu 13:66c8e4ce4ff1 136
Adrian Suciu 13:66c8e4ce4ff1 137 /**
Adrian Suciu 13:66c8e4ce4ff1 138 * Reads the filter register and returns its value
Adrian Suciu 13:66c8e4ce4ff1 139 * @return the value of the filter register
Adrian Suciu 13:66c8e4ce4ff1 140 */
Adrian Suciu 13:66c8e4ce4ff1 141 uint8_t AD7791::read_filter_reg()
Adrian Suciu 13:66c8e4ce4ff1 142 {
Adrian Suciu 13:66c8e4ce4ff1 143 return read_reg(FILTER_REG);
Adrian Suciu 13:66c8e4ce4ff1 144 }
Adrian Suciu 13:66c8e4ce4ff1 145
Adrian Suciu 13:66c8e4ce4ff1 146 /**
Adrian Suciu 13:66c8e4ce4ff1 147 * Reads the data register and returns its value
Adrian Suciu 13:66c8e4ce4ff1 148 * @return value of the data register
Adrian Suciu 13:66c8e4ce4ff1 149 */
Adrian Suciu 13:66c8e4ce4ff1 150 uint32_t AD7791::read_data_reg()
Adrian Suciu 13:66c8e4ce4ff1 151 {
Adrian Suciu 13:66c8e4ce4ff1 152 uint32_t data_result;
Adrian Suciu 13:66c8e4ce4ff1 153 ad7791.format(8, _SPI_MODE);
Adrian Suciu 13:66c8e4ce4ff1 154 cs = false;
Adrian Suciu 13:66c8e4ce4ff1 155 ad7791.write(_DATA_READ | (static_cast<uint8_t>(_channel)));
Adrian Suciu 13:66c8e4ce4ff1 156 data_result = ((ad7791.write(_DUMMY_BYTE)) << 16);
Adrian Suciu 13:66c8e4ce4ff1 157 data_result |= ((ad7791.write(_DUMMY_BYTE)) << 8 );
Adrian Suciu 13:66c8e4ce4ff1 158 data_result |= (ad7791.write(_DUMMY_BYTE));
Adrian Suciu 13:66c8e4ce4ff1 159 cs = true;
Adrian Suciu 13:66c8e4ce4ff1 160 return data_result;
Adrian Suciu 13:66c8e4ce4ff1 161 }
Adrian Suciu 13:66c8e4ce4ff1 162
Adrian Suciu 13:66c8e4ce4ff1 163 /**
Adrian Suciu 13:66c8e4ce4ff1 164 * Reads the status register of the ADC and returns its value
Adrian Suciu 13:66c8e4ce4ff1 165 * @return value of the status reg
Adrian Suciu 13:66c8e4ce4ff1 166 */
Adrian Suciu 13:66c8e4ce4ff1 167 uint8_t AD7791::read_status_reg()
Adrian Suciu 13:66c8e4ce4ff1 168 {
Adrian Suciu 13:66c8e4ce4ff1 169 return read_reg(STATUS_REG);
Adrian Suciu 13:66c8e4ce4ff1 170 }
Adrian Suciu 13:66c8e4ce4ff1 171
Adrian Suciu 13:66c8e4ce4ff1 172
Adrian Suciu 13:66c8e4ce4ff1 173 /**
Adrian Suciu 13:66c8e4ce4ff1 174 * @brief Enables/disables continous_conversion mode
Adrian Suciu 13:66c8e4ce4ff1 175 * In Single Conversion mode, read_u16 method will read the MODE register of the ADC,
Adrian Suciu 13:66c8e4ce4ff1 176 * then write the Start single conversion bit and wait for the DOUT/RDY pin to go low,
Adrian Suciu 13:66c8e4ce4ff1 177 * When the pin is driven low, data register is read back from the ADC.
Adrian Suciu 13:66c8e4ce4ff1 178 *
Adrian Suciu 13:66c8e4ce4ff1 179 * In Continous conversion mode, read_u16 method will poll the DOUT/RDY pin, if it is low,
Adrian Suciu 13:66c8e4ce4ff1 180 * the data register is read back from the ADC.
Adrian Suciu 13:66c8e4ce4ff1 181 *
Adrian Suciu 13:66c8e4ce4ff1 182 * @param mode
Adrian Suciu 13:66c8e4ce4ff1 183 * true - continous conversion mode enabled
Adrian Suciu 13:66c8e4ce4ff1 184 * false - single conversion mode enabled
Adrian Suciu 13:66c8e4ce4ff1 185 */
Adrian Suciu 13:66c8e4ce4ff1 186 void AD7791::set_conversion_mode(AD7791Mode_t mode)
Adrian Suciu 13:66c8e4ce4ff1 187 {
Adrian Suciu 13:66c8e4ce4ff1 188 uint8_t mode_reg_val;
Adrian Suciu 13:66c8e4ce4ff1 189 mode_reg_val = read_mode_reg() & 0x3F;
Adrian Suciu 13:66c8e4ce4ff1 190 mode_reg_val = mode_reg_val | (static_cast<uint8_t>(mode));
Adrian Suciu 13:66c8e4ce4ff1 191 write_mode_reg(mode);
Adrian Suciu 13:66c8e4ce4ff1 192 }
Adrian Suciu 13:66c8e4ce4ff1 193
Adrian Suciu 13:66c8e4ce4ff1 194 /**
Adrian Suciu 13:66c8e4ce4ff1 195 * - From mbed AnalogIn API -
Adrian Suciu 13:66c8e4ce4ff1 196 * @brief Read the input voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
Adrian Suciu 13:66c8e4ce4ff1 197 * Depending on the conversion mode, this method will have different behavior. Conversion mode is set using
Adrian Suciu 13:66c8e4ce4ff1 198 * set_continous_conversion_mode(bool).
Adrian Suciu 13:66c8e4ce4ff1 199 *
Adrian Suciu 13:66c8e4ce4ff1 200 * In Single Conversion mode, read_u16 method will read the MODE register of the ADC,
Adrian Suciu 13:66c8e4ce4ff1 201 * then write the Start single conversion bit and wait for the DOUT/RDY pin to go low,
Adrian Suciu 13:66c8e4ce4ff1 202 * When the pin is driven low, data register is read back from the ADC.
Adrian Suciu 13:66c8e4ce4ff1 203 *
Adrian Suciu 13:66c8e4ce4ff1 204 * In Continous conversion mode, read_u16 method will poll the DOUT/RDY pin, if it is low,
Adrian Suciu 13:66c8e4ce4ff1 205 * the data register is read back from the ADC.
Adrian Suciu 13:66c8e4ce4ff1 206 *
Adrian Suciu 13:66c8e4ce4ff1 207 * @return 16-bit unsigned short representing the current input voltage, normalised to a 16-bit value
Adrian Suciu 13:66c8e4ce4ff1 208 * returns -1 (0xFFFF) along with a debug message if conversion failed.
Adrian Suciu 13:66c8e4ce4ff1 209 */
Adrian Suciu 13:66c8e4ce4ff1 210 uint32_t AD7791::read_u32(void)
Adrian Suciu 13:66c8e4ce4ff1 211 {
Adrian Suciu 13:66c8e4ce4ff1 212 uint32_t data_result = 0;
Adrian Suciu 13:66c8e4ce4ff1 213 ad7791.format(8, _SPI_MODE);
Adrian Suciu 13:66c8e4ce4ff1 214 cs = false;
Adrian Suciu 13:66c8e4ce4ff1 215 uint16_t timeout_cnt = 0;
Adrian Suciu 13:66c8e4ce4ff1 216 if(_continous_conversion == false) {
Adrian Suciu 13:66c8e4ce4ff1 217
Adrian Suciu 13:66c8e4ce4ff1 218 uint8_t mode_reg = read_mode_reg();
Adrian Suciu 13:66c8e4ce4ff1 219 wait_us(_DELAY_TIMING);
Adrian Suciu 13:66c8e4ce4ff1 220
Adrian Suciu 13:66c8e4ce4ff1 221 cs = false;
Adrian Suciu 13:66c8e4ce4ff1 222 mode_reg = (mode_reg & 0x3F) | MD1; // mask single conversion bits
Adrian Suciu 13:66c8e4ce4ff1 223 ad7791.write((MODE_REG << 4) | (static_cast<uint8_t>(_channel))); // start single conversion
Adrian Suciu 13:66c8e4ce4ff1 224 ad7791.write(mode_reg);
Adrian Suciu 13:66c8e4ce4ff1 225 timeout_cnt = _SINGLE_CONVERSION_TIMEOUT; // starts timeout
Adrian Suciu 13:66c8e4ce4ff1 226 } else {
Adrian Suciu 13:66c8e4ce4ff1 227 timeout_cnt = _CONTINOUS_CONVERSION_TIMEOUT; // starts timeout
Adrian Suciu 13:66c8e4ce4ff1 228 }
Adrian Suciu 16:b8a49ec95bad 229 wait_us(1);
Adrian Suciu 13:66c8e4ce4ff1 230
Adrian Suciu 13:66c8e4ce4ff1 231 while(miso) { // wait for the MISO pin to go low.
Adrian Suciu 13:66c8e4ce4ff1 232 if(timeout_cnt) {
Adrian Suciu 13:66c8e4ce4ff1 233 timeout_cnt--;
Adrian Suciu 13:66c8e4ce4ff1 234 } else {
Adrian Suciu 13:66c8e4ce4ff1 235 cs = true;
Adrian Suciu 13:66c8e4ce4ff1 236 #ifdef AD7791_DEBUG_MODE
Adrian Suciu 13:66c8e4ce4ff1 237 printf("timeout occurred reading the AD7791. "); // error, MISO line didn't toggle
Adrian Suciu 13:66c8e4ce4ff1 238 #endif
Adrian Suciu 13:66c8e4ce4ff1 239 return -1; // ERROR
Adrian Suciu 13:66c8e4ce4ff1 240 }
Adrian Suciu 13:66c8e4ce4ff1 241 wait_us(10);
Adrian Suciu 13:66c8e4ce4ff1 242 }
Adrian Suciu 13:66c8e4ce4ff1 243
Adrian Suciu 13:66c8e4ce4ff1 244 ad7791.write(_DATA_READ | (static_cast<uint8_t>(_channel)));
Adrian Suciu 13:66c8e4ce4ff1 245 data_result = ((ad7791.write(_DUMMY_BYTE)) << 16);
Adrian Suciu 13:66c8e4ce4ff1 246 data_result |= ((ad7791.write(_DUMMY_BYTE)) << 8 );
Adrian Suciu 13:66c8e4ce4ff1 247 data_result |= (ad7791.write(_DUMMY_BYTE));
Adrian Suciu 13:66c8e4ce4ff1 248 cs = true;
Adrian Suciu 13:66c8e4ce4ff1 249 return data_result;
Adrian Suciu 13:66c8e4ce4ff1 250 }
Adrian Suciu 13:66c8e4ce4ff1 251
Adrian Suciu 13:66c8e4ce4ff1 252 uint16_t AD7791::read_u16(void)
Adrian Suciu 13:66c8e4ce4ff1 253 {
Adrian Suciu 17:b8356808e8ad 254 uint32_t data = read_u32();
Adrian Suciu 17:b8356808e8ad 255 return static_cast<uint16_t>((data & 0xffff00) >> 8);
Adrian Suciu 13:66c8e4ce4ff1 256 }
Adrian Suciu 13:66c8e4ce4ff1 257
Adrian Suciu 13:66c8e4ce4ff1 258 /**
Adrian Suciu 13:66c8e4ce4ff1 259 * @brief Reads a register of the AD7791
Adrian Suciu 13:66c8e4ce4ff1 260 * @param address - address of the register
Adrian Suciu 13:66c8e4ce4ff1 261 * @return value of the register
Adrian Suciu 13:66c8e4ce4ff1 262 */
Adrian Suciu 13:66c8e4ce4ff1 263 uint16_t AD7791::read_reg(AD7791Register_t address)
Adrian Suciu 13:66c8e4ce4ff1 264 {
Adrian Suciu 13:66c8e4ce4ff1 265 uint16_t data = address << 12;
Adrian Suciu 13:66c8e4ce4ff1 266 data |= _DUMMY_BYTE;
Adrian Suciu 13:66c8e4ce4ff1 267 data |= _READ_FLAG;
Adrian Suciu 13:66c8e4ce4ff1 268 data |= (static_cast<uint8_t>(_channel) << 8);
Adrian Suciu 13:66c8e4ce4ff1 269 return write_spi(data);
Adrian Suciu 13:66c8e4ce4ff1 270 }
Adrian Suciu 13:66c8e4ce4ff1 271
Adrian Suciu 13:66c8e4ce4ff1 272 /**
Adrian Suciu 13:66c8e4ce4ff1 273 * @brief Writes a register of the AD7791
Adrian Suciu 13:66c8e4ce4ff1 274 * @param address - address of the register
Adrian Suciu 13:66c8e4ce4ff1 275 * @param reg_val - value to be written
Adrian Suciu 13:66c8e4ce4ff1 276 * @return none
Adrian Suciu 13:66c8e4ce4ff1 277 *
Adrian Suciu 13:66c8e4ce4ff1 278 */
Adrian Suciu 13:66c8e4ce4ff1 279 void AD7791::write_reg(AD7791Register_t address, uint8_t reg_val)
Adrian Suciu 13:66c8e4ce4ff1 280 {
Adrian Suciu 13:66c8e4ce4ff1 281 uint16_t spi_data = address << 12;
Adrian Suciu 13:66c8e4ce4ff1 282 spi_data |= reg_val;
Adrian Suciu 13:66c8e4ce4ff1 283 spi_data |= (static_cast<uint8_t>(_channel) << 8);
Adrian Suciu 13:66c8e4ce4ff1 284 write_spi(spi_data);
Adrian Suciu 13:66c8e4ce4ff1 285 }
Adrian Suciu 13:66c8e4ce4ff1 286
Adrian Suciu 13:66c8e4ce4ff1 287 /**
Adrian Suciu 13:66c8e4ce4ff1 288 * @brief Writes 16bit data to the AD7791 SPI interface
Adrian Suciu 13:66c8e4ce4ff1 289 * @param reg_val to be written
Adrian Suciu 13:66c8e4ce4ff1 290 * @return data returned by the AD7791
Adrian Suciu 13:66c8e4ce4ff1 291 */
Adrian Suciu 13:66c8e4ce4ff1 292 uint16_t AD7791::write_spi(uint16_t reg_val)
Adrian Suciu 13:66c8e4ce4ff1 293 {
Adrian Suciu 13:66c8e4ce4ff1 294 uint16_t data_result;
Adrian Suciu 13:66c8e4ce4ff1 295 uint8_t upper_byte = (reg_val >> 8) & 0xFF;
Adrian Suciu 13:66c8e4ce4ff1 296 uint8_t lower_byte = reg_val & 0xFF;
Adrian Suciu 13:66c8e4ce4ff1 297 ad7791.format(8, _SPI_MODE);
Adrian Suciu 13:66c8e4ce4ff1 298 cs = false;
Adrian Suciu 13:66c8e4ce4ff1 299 data_result = (ad7791.write(upper_byte) << 8);
Adrian Suciu 13:66c8e4ce4ff1 300 data_result |= ad7791.write(lower_byte);
Adrian Suciu 13:66c8e4ce4ff1 301 cs = true;
Adrian Suciu 13:66c8e4ce4ff1 302 return data_result;
Adrian Suciu 13:66c8e4ce4ff1 303 }
Adrian Suciu 13:66c8e4ce4ff1 304
Adrian Suciu 13:66c8e4ce4ff1 305 /**
Adrian Suciu 13:66c8e4ce4ff1 306 * Sets the reference voltage of the AD7790
Adrian Suciu 13:66c8e4ce4ff1 307 * @param ref reference voltage to be set
Adrian Suciu 13:66c8e4ce4ff1 308 */
Adrian Suciu 13:66c8e4ce4ff1 309 void AD7791::set_reference_voltage(float ref)
Adrian Suciu 13:66c8e4ce4ff1 310 {
Adrian Suciu 13:66c8e4ce4ff1 311 _vref = ref;
Adrian Suciu 13:66c8e4ce4ff1 312 }
Adrian Suciu 13:66c8e4ce4ff1 313
Adrian Suciu 13:66c8e4ce4ff1 314 /**
Adrian Suciu 13:66c8e4ce4ff1 315 * Gets the reference voltage of the AD7790
Adrian Suciu 13:66c8e4ce4ff1 316 * @return reference voltage
Adrian Suciu 13:66c8e4ce4ff1 317 */
Adrian Suciu 13:66c8e4ce4ff1 318 float AD7791::get_reference_voltage(void)
Adrian Suciu 13:66c8e4ce4ff1 319 {
Adrian Suciu 13:66c8e4ce4ff1 320 return _vref;
Adrian Suciu 13:66c8e4ce4ff1 321 }
Adrian Suciu 13:66c8e4ce4ff1 322
Adrian Suciu 13:66c8e4ce4ff1 323 /**
Adrian Suciu 13:66c8e4ce4ff1 324 * Reads the data register of the ADC and converts the result to volts
Adrian Suciu 13:66c8e4ce4ff1 325 * Gain needs to be correctly set using set_gain in order to get accurate results
Adrian Suciu 13:66c8e4ce4ff1 326 * @return voltage of the ADC input
Adrian Suciu 13:66c8e4ce4ff1 327 */
Adrian Suciu 13:66c8e4ce4ff1 328 float AD7791::read_voltage(void)
Adrian Suciu 13:66c8e4ce4ff1 329 {
Adrian Suciu 13:66c8e4ce4ff1 330 return data_to_voltage(read_u32());
Adrian Suciu 13:66c8e4ce4ff1 331 }
Adrian Suciu 13:66c8e4ce4ff1 332
Adrian Suciu 13:66c8e4ce4ff1 333 /**
Adrian Suciu 13:66c8e4ce4ff1 334 * Converts an uint16_t to voltage.
Adrian Suciu 13:66c8e4ce4ff1 335 * Gain needs to be correctly set using set_gain in order to get accurate results
Adrian Suciu 13:66c8e4ce4ff1 336 * @param data in uint16_t format
Adrian Suciu 13:66c8e4ce4ff1 337 * @return float value of voltage (in V)
Adrian Suciu 13:66c8e4ce4ff1 338 */
Adrian Suciu 13:66c8e4ce4ff1 339 float AD7791::data_to_voltage(uint32_t data)
Adrian Suciu 13:66c8e4ce4ff1 340 {
Adrian Suciu 13:66c8e4ce4ff1 341 return ((data / static_cast<float>(_RESOLUTION / 2)) - 1) * (_vref );
Adrian Suciu 13:66c8e4ce4ff1 342 }
Adrian Suciu 13:66c8e4ce4ff1 343
Adrian Suciu 13:66c8e4ce4ff1 344 /**
Adrian Suciu 13:66c8e4ce4ff1 345 * Converts voltage to an uint16_t.
Adrian Suciu 13:66c8e4ce4ff1 346 * Gain needs to be correctly set using set_gain in order to get accurate results
Adrian Suciu 13:66c8e4ce4ff1 347 * @param voltage to be converted
Adrian Suciu 13:66c8e4ce4ff1 348 * @return data in uint16_t format
Adrian Suciu 13:66c8e4ce4ff1 349 */
Adrian Suciu 13:66c8e4ce4ff1 350 uint32_t AD7791::voltage_to_data(float voltage)
Adrian Suciu 13:66c8e4ce4ff1 351 {
Adrian Suciu 13:66c8e4ce4ff1 352 return (((voltage / _vref) + 1) * static_cast<float>(_RESOLUTION / 2));
Adrian Suciu 13:66c8e4ce4ff1 353 }
Adrian Suciu 13:66c8e4ce4ff1 354
Adrian Suciu 13:66c8e4ce4ff1 355 /**
Adrian Suciu 13:66c8e4ce4ff1 356 * Sets the conversion channel.
Adrian Suciu 13:66c8e4ce4ff1 357 * @param channel
Adrian Suciu 13:66c8e4ce4ff1 358 */
Adrian Suciu 13:66c8e4ce4ff1 359 void AD7791::set_channel(AD7791Channel_t channel)
Adrian Suciu 13:66c8e4ce4ff1 360 {
Adrian Suciu 13:66c8e4ce4ff1 361 _channel = channel;
Adrian Suciu 13:66c8e4ce4ff1 362 }
Adrian Suciu 13:66c8e4ce4ff1 363
Adrian Suciu 13:66c8e4ce4ff1 364 /**
Adrian Suciu 13:66c8e4ce4ff1 365 * - From mbed AnalogIn API -
Adrian Suciu 13:66c8e4ce4ff1 366 * Read the input voltage, represented as a float in the range [0.0, 1.0] - uses the read_u16 method
Adrian Suciu 13:66c8e4ce4ff1 367 * @returns A floating-point value representing the current input voltage, measured as a percentage
Adrian Suciu 13:66c8e4ce4ff1 368 * returns 1.0 along with a debug message if the conversion failed
Adrian Suciu 13:66c8e4ce4ff1 369 */
Adrian Suciu 13:66c8e4ce4ff1 370 float AD7791::read(void)
Adrian Suciu 13:66c8e4ce4ff1 371 {
Adrian Suciu 13:66c8e4ce4ff1 372 float percent;
Adrian Suciu 13:66c8e4ce4ff1 373 uint32_t data;
Adrian Suciu 13:66c8e4ce4ff1 374 data = read_u32();
Adrian Suciu 13:66c8e4ce4ff1 375 percent = (data / static_cast<float>(_RESOLUTION) ); // translate bipolar conversion to [0.0, 1.0] domain
Adrian Suciu 13:66c8e4ce4ff1 376 return percent;
Adrian Suciu 13:66c8e4ce4ff1 377 }
Adrian Suciu 13:66c8e4ce4ff1 378
Adrian Suciu 13:66c8e4ce4ff1 379 #ifdef MBED_OPERATORS
Adrian Suciu 13:66c8e4ce4ff1 380
Adrian Suciu 13:66c8e4ce4ff1 381 /**
Adrian Suciu 13:66c8e4ce4ff1 382 * - From mbed AnalogIn API -
Adrian Suciu 13:66c8e4ce4ff1 383 * An operator shorthand for read()
Adrian Suciu 13:66c8e4ce4ff1 384 * The float() operator can be used as a shorthand for read() to simplify common code sequences
Adrian Suciu 13:66c8e4ce4ff1 385 */
Adrian Suciu 13:66c8e4ce4ff1 386 AD7791::operator float()
Adrian Suciu 13:66c8e4ce4ff1 387 {
Adrian Suciu 13:66c8e4ce4ff1 388 return read();
Adrian Suciu 13:66c8e4ce4ff1 389 }
Adrian Suciu 13:66c8e4ce4ff1 390
Adrian Suciu 13:66c8e4ce4ff1 391 #endif
Adrian Suciu 13:66c8e4ce4ff1 392
Adrian Suciu 13:66c8e4ce4ff1 393
Adrian Suciu 13:66c8e4ce4ff1 394