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@33:c3ec596a29c2, 2016-11-07 (annotated)

Committer:
Adrian Suciu
Date:
Mon Nov 07 16:27:12 2016 +0200
Revision:
33:c3ec596a29c2
Parent:
24:dae7123d432a 
Added CN0391, CN0396 and CN0397 shields

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Adrian Suciu 24:dae7123d432a 1 /**
Adrian Suciu 24:dae7123d432a 2 * @file AD7791.cpp
Adrian Suciu 24:dae7123d432a 3 * @brief Source file for AD7791 ADC
Adrian Suciu 24:dae7123d432a 4 * @author Analog Devices Inc.
Adrian Suciu 24:dae7123d432a 5 *
Adrian Suciu 24:dae7123d432a 6 * For support please go to:
Adrian Suciu 24:dae7123d432a 7 * Github: https://github.com/analogdevicesinc/mbed-adi
Adrian Suciu 24:dae7123d432a 8 * Support: https://ez.analog.com/community/linux-device-drivers/microcontroller-no-os-drivers
Adrian Suciu 24:dae7123d432a 9 * Product: http://www.analog.com/ad7791
Adrian Suciu 24:dae7123d432a 10 * More: https://wiki.analog.com/resources/tools-software/mbed-drivers-all
Adrian Suciu 24:dae7123d432a 11
Adrian Suciu 24:dae7123d432a 12 ********************************************************************************
Adrian Suciu 24:dae7123d432a 13 * Copyright 2016(c) Analog Devices, Inc.
Adrian Suciu 24:dae7123d432a 14 *
Adrian Suciu 24:dae7123d432a 15 * All rights reserved.
Adrian Suciu 24:dae7123d432a 16 *
Adrian Suciu 24:dae7123d432a 17 * Redistribution and use in source and binary forms, with or without
Adrian Suciu 24:dae7123d432a 18 * modification, are permitted provided that the following conditions are met:
Adrian Suciu 24:dae7123d432a 19 * - Redistributions of source code must retain the above copyright
Adrian Suciu 24:dae7123d432a 20 * notice, this list of conditions and the following disclaimer.
Adrian Suciu 24:dae7123d432a 21 * - Redistributions in binary form must reproduce the above copyright
Adrian Suciu 24:dae7123d432a 22 * notice, this list of conditions and the following disclaimer in
Adrian Suciu 24:dae7123d432a 23 * the documentation and/or other materials provided with the
Adrian Suciu 24:dae7123d432a 24 * distribution.
Adrian Suciu 24:dae7123d432a 25 * - Neither the name of Analog Devices, Inc. nor the names of its
Adrian Suciu 24:dae7123d432a 26 * contributors may be used to endorse or promote products derived
Adrian Suciu 24:dae7123d432a 27 * from this software without specific prior written permission.
Adrian Suciu 24:dae7123d432a 28 * - The use of this software may or may not infringe the patent rights
Adrian Suciu 24:dae7123d432a 29 * of one or more patent holders. This license does not release you
Adrian Suciu 24:dae7123d432a 30 * from the requirement that you obtain separate licenses from these
Adrian Suciu 24:dae7123d432a 31 * patent holders to use this software.
Adrian Suciu 24:dae7123d432a 32 * - Use of the software either in source or binary form, must be run
Adrian Suciu 24:dae7123d432a 33 * on or directly connected to an Analog Devices Inc. component.
Adrian Suciu 24:dae7123d432a 34 *
Adrian Suciu 24:dae7123d432a 35 * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
Adrian Suciu 24:dae7123d432a 36 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
Adrian Suciu 24:dae7123d432a 37 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
Adrian Suciu 24:dae7123d432a 38 * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
Adrian Suciu 24:dae7123d432a 39 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
Adrian Suciu 24:dae7123d432a 40 * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
Adrian Suciu 24:dae7123d432a 41 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
Adrian Suciu 24:dae7123d432a 42 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
Adrian Suciu 24:dae7123d432a 43 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
Adrian Suciu 24:dae7123d432a 44 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Adrian Suciu 24:dae7123d432a 45 *
Adrian Suciu 24:dae7123d432a 46 ********************************************************************************/
Adrian Suciu 24:dae7123d432a 47
Adrian Suciu 24:dae7123d432a 48 #include <stdint.h>
Adrian Suciu 24:dae7123d432a 49 #include "mbed.h"
Adrian Suciu 24:dae7123d432a 50 #include "AD7791.h"
Adrian Suciu 24:dae7123d432a 51
Adrian Suciu 24:dae7123d432a 52 /**
Adrian Suciu 24:dae7123d432a 53 * @brief AD7791 constructor, sets CS pin and SPI format
Adrian Suciu 24:dae7123d432a 54 * @param reference_voltage - the reference voltage to be used in computation
Adrian Suciu 24:dae7123d432a 55 * @param CS - (optional)chip select of the AD7791
Adrian Suciu 24:dae7123d432a 56 * @param MOSI - (optional)pin of the SPI interface
Adrian Suciu 24:dae7123d432a 57 * @param MISO - (optional)pin of the SPI interface
Adrian Suciu 24:dae7123d432a 58 * @param SCK - (optional)pin of the SPI interface
Adrian Suciu 24:dae7123d432a 59 */
Adrian Suciu 24:dae7123d432a 60 AD7791::AD7791(float reference_voltage,
Adrian Suciu 24:dae7123d432a 61 PinName CS,
Adrian Suciu 24:dae7123d432a 62 PinName MOSI,
Adrian Suciu 24:dae7123d432a 63 PinName MISO,
Adrian Suciu 24:dae7123d432a 64 PinName SCK) :
Adrian Suciu 24:dae7123d432a 65 miso(MISO), ad7791(MOSI, MISO, SCK), cs(CS), _vref(reference_voltage)
Adrian Suciu 24:dae7123d432a 66 {
Adrian Suciu 24:dae7123d432a 67 cs = true; // cs is active low
Adrian Suciu 24:dae7123d432a 68 ad7791.format(8, _SPI_MODE);
Adrian Suciu 24:dae7123d432a 69 _continous_conversion = true;
Adrian Suciu 24:dae7123d432a 70 _channel = DIFFERENTIAL;
Adrian Suciu 24:dae7123d432a 71 }
Adrian Suciu 24:dae7123d432a 72
Adrian Suciu 24:dae7123d432a 73 /**
Adrian Suciu 24:dae7123d432a 74 * @brief Set AD7791 SPI frequency
Adrian Suciu 24:dae7123d432a 75 * @param hz - SPI bus frequency in hz
Adrian Suciu 24:dae7123d432a 76 * @return none
Adrian Suciu 24:dae7123d432a 77 */
Adrian Suciu 24:dae7123d432a 78 void AD7791::frequency(int hz)
Adrian Suciu 24:dae7123d432a 79 {
Adrian Suciu 24:dae7123d432a 80 ad7791.frequency(hz);
Adrian Suciu 24:dae7123d432a 81 }
Adrian Suciu 24:dae7123d432a 82
Adrian Suciu 24:dae7123d432a 83 /**
Adrian Suciu 24:dae7123d432a 84 * @brief Resets the AD7791
Adrian Suciu 24:dae7123d432a 85 * @return none
Adrian Suciu 24:dae7123d432a 86 */
Adrian Suciu 24:dae7123d432a 87 void AD7791::reset()
Adrian Suciu 24:dae7123d432a 88 {
Adrian Suciu 24:dae7123d432a 89 ad7791.format(8, _SPI_MODE);
Adrian Suciu 24:dae7123d432a 90 cs = false;
Adrian Suciu 24:dae7123d432a 91 wait_us(_DELAY_TIMING);
Adrian Suciu 24:dae7123d432a 92 ad7791.write(_RESET);
Adrian Suciu 24:dae7123d432a 93 ad7791.write(_RESET);
Adrian Suciu 24:dae7123d432a 94 ad7791.write(_RESET);
Adrian Suciu 24:dae7123d432a 95 ad7791.write(_RESET);
Adrian Suciu 24:dae7123d432a 96 wait_us(_DELAY_TIMING);
Adrian Suciu 24:dae7123d432a 97 cs = true;
Adrian Suciu 24:dae7123d432a 98 _continous_conversion = true;
Adrian Suciu 24:dae7123d432a 99 }
Adrian Suciu 24:dae7123d432a 100
Adrian Suciu 24:dae7123d432a 101 /**
Adrian Suciu 24:dae7123d432a 102 * Sets the mode register. Also sets continous mode and range based on the value
Adrian Suciu 24:dae7123d432a 103 * written in reg_val
Adrian Suciu 24:dae7123d432a 104 * @param reg_val
Adrian Suciu 24:dae7123d432a 105 */
Adrian Suciu 24:dae7123d432a 106 void AD7791::write_mode_reg(uint8_t reg_val)
Adrian Suciu 24:dae7123d432a 107 {
Adrian Suciu 24:dae7123d432a 108 write_reg(MODE_REG, reg_val);
Adrian Suciu 24:dae7123d432a 109 uint8_t continous_mode = (reg_val & 0xC0);
Adrian Suciu 24:dae7123d432a 110 if(continous_mode == 0x00) {
Adrian Suciu 24:dae7123d432a 111 _continous_conversion = true;
Adrian Suciu 24:dae7123d432a 112 } else {
Adrian Suciu 24:dae7123d432a 113 _continous_conversion = false;
Adrian Suciu 24:dae7123d432a 114 }
Adrian Suciu 24:dae7123d432a 115 /* uint8_t range = (reg_val & 0x30);
Adrian Suciu 24:dae7123d432a 116 _PGA_gain = 1 << (range >> 4);*/
Adrian Suciu 24:dae7123d432a 117
Adrian Suciu 24:dae7123d432a 118 }
Adrian Suciu 24:dae7123d432a 119
Adrian Suciu 24:dae7123d432a 120 /**
Adrian Suciu 24:dae7123d432a 121 * Reads the mode register and returns its value
Adrian Suciu 24:dae7123d432a 122 * @return value of the mode register
Adrian Suciu 24:dae7123d432a 123 */
Adrian Suciu 24:dae7123d432a 124 uint8_t AD7791::read_mode_reg()
Adrian Suciu 24:dae7123d432a 125 {
Adrian Suciu 24:dae7123d432a 126 return read_reg(MODE_REG);
Adrian Suciu 24:dae7123d432a 127 }
Adrian Suciu 24:dae7123d432a 128
Adrian Suciu 24:dae7123d432a 129 /**
Adrian Suciu 24:dae7123d432a 130 * Writes the filter register
Adrian Suciu 24:dae7123d432a 131 * @param regValue value to be written.
Adrian Suciu 24:dae7123d432a 132 */
Adrian Suciu 24:dae7123d432a 133 void AD7791::write_filter_reg(uint8_t reg_val)
Adrian Suciu 24:dae7123d432a 134 {
Adrian Suciu 24:dae7123d432a 135 write_reg(FILTER_REG, reg_val);
Adrian Suciu 24:dae7123d432a 136 }
Adrian Suciu 24:dae7123d432a 137
Adrian Suciu 24:dae7123d432a 138 /**
Adrian Suciu 24:dae7123d432a 139 * Reads the filter register and returns its value
Adrian Suciu 24:dae7123d432a 140 * @return the value of the filter register
Adrian Suciu 24:dae7123d432a 141 */
Adrian Suciu 24:dae7123d432a 142 uint8_t AD7791::read_filter_reg()
Adrian Suciu 24:dae7123d432a 143 {
Adrian Suciu 24:dae7123d432a 144 return read_reg(FILTER_REG);
Adrian Suciu 24:dae7123d432a 145 }
Adrian Suciu 24:dae7123d432a 146
Adrian Suciu 24:dae7123d432a 147 /**
Adrian Suciu 24:dae7123d432a 148 * Reads the data register and returns its value
Adrian Suciu 24:dae7123d432a 149 * @return value of the data register
Adrian Suciu 24:dae7123d432a 150 */
Adrian Suciu 24:dae7123d432a 151 uint32_t AD7791::read_data_reg()
Adrian Suciu 24:dae7123d432a 152 {
Adrian Suciu 24:dae7123d432a 153 uint32_t data_result;
Adrian Suciu 24:dae7123d432a 154 ad7791.format(8, _SPI_MODE);
Adrian Suciu 24:dae7123d432a 155 cs = false;
Adrian Suciu 24:dae7123d432a 156 ad7791.write(_DATA_READ | (static_cast<uint8_t>(_channel)));
Adrian Suciu 24:dae7123d432a 157 data_result = ((ad7791.write(_DUMMY_BYTE)) << 16);
Adrian Suciu 24:dae7123d432a 158 data_result |= ((ad7791.write(_DUMMY_BYTE)) << 8 );
Adrian Suciu 24:dae7123d432a 159 data_result |= (ad7791.write(_DUMMY_BYTE));
Adrian Suciu 24:dae7123d432a 160 cs = true;
Adrian Suciu 24:dae7123d432a 161 return data_result;
Adrian Suciu 24:dae7123d432a 162 }
Adrian Suciu 24:dae7123d432a 163
Adrian Suciu 24:dae7123d432a 164 /**
Adrian Suciu 24:dae7123d432a 165 * Reads the status register of the ADC and returns its value
Adrian Suciu 24:dae7123d432a 166 * @return value of the status reg
Adrian Suciu 24:dae7123d432a 167 */
Adrian Suciu 24:dae7123d432a 168 uint8_t AD7791::read_status_reg()
Adrian Suciu 24:dae7123d432a 169 {
Adrian Suciu 24:dae7123d432a 170 return read_reg(STATUS_REG);
Adrian Suciu 24:dae7123d432a 171 }
Adrian Suciu 24:dae7123d432a 172
Adrian Suciu 24:dae7123d432a 173
Adrian Suciu 24:dae7123d432a 174 /**
Adrian Suciu 24:dae7123d432a 175 * @brief Enables/disables continous_conversion mode
Adrian Suciu 24:dae7123d432a 176 * In Single Conversion mode, read_u16 method will read the MODE register of the ADC,
Adrian Suciu 24:dae7123d432a 177 * then write the Start single conversion bit and wait for the DOUT/RDY pin to go low,
Adrian Suciu 24:dae7123d432a 178 * When the pin is driven low, data register is read back from the ADC.
Adrian Suciu 24:dae7123d432a 179 *
Adrian Suciu 24:dae7123d432a 180 * In Continous conversion mode, read_u16 method will poll the DOUT/RDY pin, if it is low,
Adrian Suciu 24:dae7123d432a 181 * the data register is read back from the ADC.
Adrian Suciu 24:dae7123d432a 182 *
Adrian Suciu 24:dae7123d432a 183 * @param mode
Adrian Suciu 24:dae7123d432a 184 * true - continous conversion mode enabled
Adrian Suciu 24:dae7123d432a 185 * false - single conversion mode enabled
Adrian Suciu 24:dae7123d432a 186 */
Adrian Suciu 24:dae7123d432a 187 void AD7791::set_conversion_mode(AD7791Mode_t mode)
Adrian Suciu 24:dae7123d432a 188 {
Adrian Suciu 24:dae7123d432a 189 uint8_t mode_reg_val;
Adrian Suciu 24:dae7123d432a 190 mode_reg_val = read_mode_reg() & 0x3F;
Adrian Suciu 24:dae7123d432a 191 mode_reg_val = mode_reg_val | (static_cast<uint8_t>(mode));
Adrian Suciu 24:dae7123d432a 192 write_mode_reg(mode);
Adrian Suciu 24:dae7123d432a 193 }
Adrian Suciu 24:dae7123d432a 194
Adrian Suciu 24:dae7123d432a 195 /**
Adrian Suciu 24:dae7123d432a 196 * - From mbed AnalogIn API -
Adrian Suciu 24:dae7123d432a 197 * @brief Read the input voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
Adrian Suciu 24:dae7123d432a 198 * Depending on the conversion mode, this method will have different behavior. Conversion mode is set using
Adrian Suciu 24:dae7123d432a 199 * set_continous_conversion_mode(bool).
Adrian Suciu 24:dae7123d432a 200 *
Adrian Suciu 24:dae7123d432a 201 * In Single Conversion mode, read_u16 method will read the MODE register of the ADC,
Adrian Suciu 24:dae7123d432a 202 * then write the Start single conversion bit and wait for the DOUT/RDY pin to go low,
Adrian Suciu 24:dae7123d432a 203 * When the pin is driven low, data register is read back from the ADC.
Adrian Suciu 24:dae7123d432a 204 *
Adrian Suciu 24:dae7123d432a 205 * In Continous conversion mode, read_u16 method will poll the DOUT/RDY pin, if it is low,
Adrian Suciu 24:dae7123d432a 206 * the data register is read back from the ADC.
Adrian Suciu 24:dae7123d432a 207 *
Adrian Suciu 24:dae7123d432a 208 * @return 16-bit unsigned short representing the current input voltage, normalised to a 16-bit value
Adrian Suciu 24:dae7123d432a 209 * returns -1 (0xFFFF) along with a debug message if conversion failed.
Adrian Suciu 24:dae7123d432a 210 */
Adrian Suciu 24:dae7123d432a 211 uint32_t AD7791::read_u32(void)
Adrian Suciu 24:dae7123d432a 212 {
Adrian Suciu 24:dae7123d432a 213 uint32_t data_result = 0;
Adrian Suciu 24:dae7123d432a 214 ad7791.format(8, _SPI_MODE);
Adrian Suciu 24:dae7123d432a 215 cs = false;
Adrian Suciu 24:dae7123d432a 216 uint16_t timeout_cnt = 0;
Adrian Suciu 24:dae7123d432a 217 if(_continous_conversion == false) {
Adrian Suciu 24:dae7123d432a 218
Adrian Suciu 24:dae7123d432a 219 uint8_t mode_reg = read_mode_reg();
Adrian Suciu 24:dae7123d432a 220 wait_us(_DELAY_TIMING);
Adrian Suciu 24:dae7123d432a 221
Adrian Suciu 24:dae7123d432a 222 cs = false;
Adrian Suciu 24:dae7123d432a 223 mode_reg = (mode_reg & 0x3F) | MD1; // mask single conversion bits
Adrian Suciu 24:dae7123d432a 224 ad7791.write((MODE_REG << 4) | (static_cast<uint8_t>(_channel))); // start single conversion
Adrian Suciu 24:dae7123d432a 225 ad7791.write(mode_reg);
Adrian Suciu 24:dae7123d432a 226 timeout_cnt = _SINGLE_CONVERSION_TIMEOUT; // starts timeout
Adrian Suciu 24:dae7123d432a 227 } else {
Adrian Suciu 24:dae7123d432a 228 timeout_cnt = _CONTINOUS_CONVERSION_TIMEOUT; // starts timeout
Adrian Suciu 24:dae7123d432a 229 }
Adrian Suciu 24:dae7123d432a 230 wait_us(1);
Adrian Suciu 24:dae7123d432a 231
Adrian Suciu 24:dae7123d432a 232 while(miso) { // wait for the MISO pin to go low.
Adrian Suciu 24:dae7123d432a 233 if(timeout_cnt) {
Adrian Suciu 24:dae7123d432a 234 timeout_cnt--;
Adrian Suciu 24:dae7123d432a 235 } else {
Adrian Suciu 24:dae7123d432a 236 cs = true;
Adrian Suciu 24:dae7123d432a 237 #ifdef AD7791_DEBUG_MODE
Adrian Suciu 24:dae7123d432a 238 printf("timeout occurred reading the AD7791. "); // error, MISO line didn't toggle
Adrian Suciu 24:dae7123d432a 239 #endif
Adrian Suciu 24:dae7123d432a 240 return -1; // ERROR
Adrian Suciu 24:dae7123d432a 241 }
Adrian Suciu 24:dae7123d432a 242 wait_us(10);
Adrian Suciu 24:dae7123d432a 243 }
Adrian Suciu 24:dae7123d432a 244
Adrian Suciu 24:dae7123d432a 245 ad7791.write(_DATA_READ | (static_cast<uint8_t>(_channel)));
Adrian Suciu 24:dae7123d432a 246 data_result = ((ad7791.write(_DUMMY_BYTE)) << 16);
Adrian Suciu 24:dae7123d432a 247 data_result |= ((ad7791.write(_DUMMY_BYTE)) << 8 );
Adrian Suciu 24:dae7123d432a 248 data_result |= (ad7791.write(_DUMMY_BYTE));
Adrian Suciu 24:dae7123d432a 249 cs = true;
Adrian Suciu 24:dae7123d432a 250 return data_result;
Adrian Suciu 24:dae7123d432a 251 }
Adrian Suciu 24:dae7123d432a 252
Adrian Suciu 24:dae7123d432a 253 uint16_t AD7791::read_u16(void)
Adrian Suciu 24:dae7123d432a 254 {
Adrian Suciu 24:dae7123d432a 255 uint32_t data = read_u32();
Adrian Suciu 24:dae7123d432a 256 return static_cast<uint16_t>((data & 0xffff00) >> 8);
Adrian Suciu 24:dae7123d432a 257 }
Adrian Suciu 24:dae7123d432a 258
Adrian Suciu 24:dae7123d432a 259 /**
Adrian Suciu 24:dae7123d432a 260 * @brief Reads a register of the AD7791
Adrian Suciu 24:dae7123d432a 261 * @param address - address of the register
Adrian Suciu 24:dae7123d432a 262 * @return value of the register
Adrian Suciu 24:dae7123d432a 263 */
Adrian Suciu 24:dae7123d432a 264 uint16_t AD7791::read_reg(AD7791Register_t address)
Adrian Suciu 24:dae7123d432a 265 {
Adrian Suciu 24:dae7123d432a 266 uint16_t data = address << 12;
Adrian Suciu 24:dae7123d432a 267 data |= _DUMMY_BYTE;
Adrian Suciu 24:dae7123d432a 268 data |= _READ_FLAG;
Adrian Suciu 24:dae7123d432a 269 data |= (static_cast<uint8_t>(_channel) << 8);
Adrian Suciu 24:dae7123d432a 270 return write_spi(data);
Adrian Suciu 24:dae7123d432a 271 }
Adrian Suciu 24:dae7123d432a 272
Adrian Suciu 24:dae7123d432a 273 /**
Adrian Suciu 24:dae7123d432a 274 * @brief Writes a register of the AD7791
Adrian Suciu 24:dae7123d432a 275 * @param address - address of the register
Adrian Suciu 24:dae7123d432a 276 * @param reg_val - value to be written
Adrian Suciu 24:dae7123d432a 277 * @return none
Adrian Suciu 24:dae7123d432a 278 *
Adrian Suciu 24:dae7123d432a 279 */
Adrian Suciu 24:dae7123d432a 280 void AD7791::write_reg(AD7791Register_t address, uint8_t reg_val)
Adrian Suciu 24:dae7123d432a 281 {
Adrian Suciu 24:dae7123d432a 282 uint16_t spi_data = address << 12;
Adrian Suciu 24:dae7123d432a 283 spi_data |= reg_val;
Adrian Suciu 24:dae7123d432a 284 spi_data |= (static_cast<uint8_t>(_channel) << 8);
Adrian Suciu 24:dae7123d432a 285 write_spi(spi_data);
Adrian Suciu 24:dae7123d432a 286 }
Adrian Suciu 24:dae7123d432a 287
Adrian Suciu 24:dae7123d432a 288 /**
Adrian Suciu 24:dae7123d432a 289 * @brief Writes 16bit data to the AD7791 SPI interface
Adrian Suciu 24:dae7123d432a 290 * @param reg_val to be written
Adrian Suciu 24:dae7123d432a 291 * @return data returned by the AD7791
Adrian Suciu 24:dae7123d432a 292 */
Adrian Suciu 24:dae7123d432a 293 uint16_t AD7791::write_spi(uint16_t reg_val)
Adrian Suciu 24:dae7123d432a 294 {
Adrian Suciu 24:dae7123d432a 295 uint16_t data_result;
Adrian Suciu 24:dae7123d432a 296 uint8_t upper_byte = (reg_val >> 8) & 0xFF;
Adrian Suciu 24:dae7123d432a 297 uint8_t lower_byte = reg_val & 0xFF;
Adrian Suciu 24:dae7123d432a 298 ad7791.format(8, _SPI_MODE);
Adrian Suciu 24:dae7123d432a 299 cs = false;
Adrian Suciu 24:dae7123d432a 300 data_result = (ad7791.write(upper_byte) << 8);
Adrian Suciu 24:dae7123d432a 301 data_result |= ad7791.write(lower_byte);
Adrian Suciu 24:dae7123d432a 302 cs = true;
Adrian Suciu 24:dae7123d432a 303 return data_result;
Adrian Suciu 24:dae7123d432a 304 }
Adrian Suciu 24:dae7123d432a 305
Adrian Suciu 24:dae7123d432a 306 /**
Adrian Suciu 24:dae7123d432a 307 * Sets the reference voltage of the AD7790
Adrian Suciu 24:dae7123d432a 308 * @param ref reference voltage to be set
Adrian Suciu 24:dae7123d432a 309 */
Adrian Suciu 24:dae7123d432a 310 void AD7791::set_reference_voltage(float ref)
Adrian Suciu 24:dae7123d432a 311 {
Adrian Suciu 24:dae7123d432a 312 _vref = ref;
Adrian Suciu 24:dae7123d432a 313 }
Adrian Suciu 24:dae7123d432a 314
Adrian Suciu 24:dae7123d432a 315 /**
Adrian Suciu 24:dae7123d432a 316 * Gets the reference voltage of the AD7790
Adrian Suciu 24:dae7123d432a 317 * @return reference voltage
Adrian Suciu 24:dae7123d432a 318 */
Adrian Suciu 24:dae7123d432a 319 float AD7791::get_reference_voltage(void)
Adrian Suciu 24:dae7123d432a 320 {
Adrian Suciu 24:dae7123d432a 321 return _vref;
Adrian Suciu 24:dae7123d432a 322 }
Adrian Suciu 24:dae7123d432a 323
Adrian Suciu 24:dae7123d432a 324 /**
Adrian Suciu 24:dae7123d432a 325 * Reads the data register of the ADC and converts the result to volts
Adrian Suciu 24:dae7123d432a 326 * Gain needs to be correctly set using set_gain in order to get accurate results
Adrian Suciu 24:dae7123d432a 327 * @return voltage of the ADC input
Adrian Suciu 24:dae7123d432a 328 */
Adrian Suciu 24:dae7123d432a 329 float AD7791::read_voltage(void)
Adrian Suciu 24:dae7123d432a 330 {
Adrian Suciu 24:dae7123d432a 331 return data_to_voltage(read_u32());
Adrian Suciu 24:dae7123d432a 332 }
Adrian Suciu 24:dae7123d432a 333
Adrian Suciu 24:dae7123d432a 334 /**
Adrian Suciu 24:dae7123d432a 335 * Converts an uint16_t to voltage.
Adrian Suciu 24:dae7123d432a 336 * Gain needs to be correctly set using set_gain in order to get accurate results
Adrian Suciu 24:dae7123d432a 337 * @param data in uint16_t format
Adrian Suciu 24:dae7123d432a 338 * @return float value of voltage (in V)
Adrian Suciu 24:dae7123d432a 339 */
Adrian Suciu 24:dae7123d432a 340 float AD7791::data_to_voltage(uint32_t data)
Adrian Suciu 24:dae7123d432a 341 {
Adrian Suciu 24:dae7123d432a 342 return ((data / static_cast<float>(_RESOLUTION / 2)) - 1) * (_vref );
Adrian Suciu 24:dae7123d432a 343 }
Adrian Suciu 24:dae7123d432a 344
Adrian Suciu 24:dae7123d432a 345 /**
Adrian Suciu 24:dae7123d432a 346 * Converts voltage to an uint16_t.
Adrian Suciu 24:dae7123d432a 347 * Gain needs to be correctly set using set_gain in order to get accurate results
Adrian Suciu 24:dae7123d432a 348 * @param voltage to be converted
Adrian Suciu 24:dae7123d432a 349 * @return data in uint16_t format
Adrian Suciu 24:dae7123d432a 350 */
Adrian Suciu 24:dae7123d432a 351 uint32_t AD7791::voltage_to_data(float voltage)
Adrian Suciu 24:dae7123d432a 352 {
Adrian Suciu 24:dae7123d432a 353 return (((voltage / _vref) + 1) * static_cast<float>(_RESOLUTION / 2));
Adrian Suciu 24:dae7123d432a 354 }
Adrian Suciu 24:dae7123d432a 355
Adrian Suciu 24:dae7123d432a 356 /**
Adrian Suciu 24:dae7123d432a 357 * Sets the conversion channel.
Adrian Suciu 24:dae7123d432a 358 * @param channel
Adrian Suciu 24:dae7123d432a 359 */
Adrian Suciu 24:dae7123d432a 360 void AD7791::set_channel(AD7791Channel_t channel)
Adrian Suciu 24:dae7123d432a 361 {
Adrian Suciu 24:dae7123d432a 362 _channel = channel;
Adrian Suciu 24:dae7123d432a 363 }
Adrian Suciu 24:dae7123d432a 364
Adrian Suciu 24:dae7123d432a 365 /**
Adrian Suciu 24:dae7123d432a 366 * - From mbed AnalogIn API -
Adrian Suciu 24:dae7123d432a 367 * Read the input voltage, represented as a float in the range [0.0, 1.0] - uses the read_u16 method
Adrian Suciu 24:dae7123d432a 368 * @returns A floating-point value representing the current input voltage, measured as a percentage
Adrian Suciu 24:dae7123d432a 369 * returns 1.0 along with a debug message if the conversion failed
Adrian Suciu 24:dae7123d432a 370 */
Adrian Suciu 24:dae7123d432a 371 float AD7791::read(void)
Adrian Suciu 24:dae7123d432a 372 {
Adrian Suciu 24:dae7123d432a 373 float percent;
Adrian Suciu 24:dae7123d432a 374 uint32_t data;
Adrian Suciu 24:dae7123d432a 375 data = read_u32();
Adrian Suciu 24:dae7123d432a 376 percent = (data / static_cast<float>(_RESOLUTION) ); // translate bipolar conversion to [0.0, 1.0] domain
Adrian Suciu 24:dae7123d432a 377 return percent;
Adrian Suciu 24:dae7123d432a 378 }
Adrian Suciu 24:dae7123d432a 379
Adrian Suciu 24:dae7123d432a 380 #ifdef MBED_OPERATORS
Adrian Suciu 24:dae7123d432a 381
Adrian Suciu 24:dae7123d432a 382 /**
Adrian Suciu 24:dae7123d432a 383 * - From mbed AnalogIn API -
Adrian Suciu 24:dae7123d432a 384 * An operator shorthand for read()
Adrian Suciu 24:dae7123d432a 385 * The float() operator can be used as a shorthand for read() to simplify common code sequences
Adrian Suciu 24:dae7123d432a 386 */
Adrian Suciu 24:dae7123d432a 387 AD7791::operator float()
Adrian Suciu 24:dae7123d432a 388 {
Adrian Suciu 24:dae7123d432a 389 return read();
Adrian Suciu 24:dae7123d432a 390 }
Adrian Suciu 24:dae7123d432a 391
Adrian Suciu 24:dae7123d432a 392 #endif
Adrian Suciu 24:dae7123d432a 393
Adrian Suciu 24:dae7123d432a 394
Adrian Suciu 24:dae7123d432a 395