AD5270.cpp

00001 /**
00002 *   @file     AD5270.cpp
00003 *   @brief    Source file for AD5270 rheostat
00004 *   @author   Analog Devices Inc.
00005 *
00006 * For support please go to:
00007 * Github: https://github.com/analogdevicesinc/mbed-adi
00008 * Support: https://ez.analog.com/community/linux-device-drivers/microcontroller-no-os-drivers
00009 * Product: http://www.analog.com/ad5270
00010 * More: https://wiki.analog.com/resources/tools-software/mbed-drivers-all
00011 
00012 ********************************************************************************
00013 * Copyright 2016(c) Analog Devices, Inc.
00014 *
00015 * All rights reserved.
00016 *
00017 * Redistribution and use in source and binary forms, with or without
00018 * modification, are permitted provided that the following conditions are met:
00019 *  - Redistributions of source code must retain the above copyright
00020 *    notice, this list of conditions and the following disclaimer.
00021 *  - Redistributions in binary form must reproduce the above copyright
00022 *    notice, this list of conditions and the following disclaimer in
00023 *    the documentation and/or other materials provided with the
00024 *    distribution.
00025 *  - Neither the name of Analog Devices, Inc. nor the names of its
00026 *    contributors may be used to endorse or promote products derived
00027 *    from this software without specific prior written permission.
00028 *  - The use of this software may or may not infringe the patent rights
00029 *    of one or more patent holders.  This license does not release you
00030 *    from the requirement that you obtain separate licenses from these
00031 *    patent holders to use this software.
00032 *  - Use of the software either in source or binary form, must be run
00033 *    on or directly connected to an Analog Devices Inc. component.
00034 *
00035 * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
00036 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
00037 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00038 * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
00039 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
00040 * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
00041 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00042 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00043 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
00044 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00045 *
00046 ********************************************************************************/
00047 
00048 
00049 #include "mbed.h"
00050 #include "AD5270.h"
00051 
00052 /**
00053  * @brief AD5270 constructor, sets CS pin and SPI format
00054  * @param CS - (optional)chip select of the AD5270
00055  * @param max_resistance - (optional) nominal resistance of the AD5270 chip in ohms
00056  * @param MOSI - (optional)pin of the SPI interface
00057  * @param MISO - (optional)pin of the SPI interface
00058  * @param SCK  - (optional)pin of the SPI interface
00059  */
00060 AD5270::AD5270(PinName CS, float max_resistance, PinName MOSI, PinName MISO, PinName SCK):
00061     ad5270(MOSI, MISO, SCK), cs(CS), _max_resistance(max_resistance)
00062 {
00063     cs = true;
00064     ad5270.format(8, _SPI_MODE);
00065 }
00066 
00067 /**
00068  * @brief Compute for the nearest RDAC value from given resistance
00069  * @param resistance - resistor
00070  * @return RDAC value - closest possible to given resistance
00071  */
00072 uint16_t AD5270::calc_RDAC(float resistance)
00073 {
00074     return static_cast<uint16_t>( (resistance / _max_resistance) * 1024.0 );
00075 }
00076 
00077 /**
00078  * @brief sets a new value for the RDAC
00079  * @param resistance new value for the resistance
00080  * @return actual value of the resistance in the RDAC
00081  */
00082 float AD5270::write_RDAC(float resistance)
00083 {
00084     // Compute for the RDAC code nearest to the required feedback resistance
00085     uint16_t RDAC_val = calc_RDAC(resistance);
00086     float RDAC_Value = ((static_cast<float> (RDAC_val) * _max_resistance) / 1024.0); // inverse operation to get actual resistance in the RDAC
00087     write_wiper_reg(RDAC_val);
00088     return RDAC_Value;
00089 }
00090 
00091 /**
00092  * Reads the RDAC register
00093  * @return RDAC resistor value
00094  */
00095 float AD5270::read_RDAC()
00096 {
00097     uint16_t RDAC_val = read_wiper_reg();
00098     return ((static_cast<float> (RDAC_val) * _max_resistance) / 1024.0);
00099 }
00100 
00101 /**
00102  *  @brief Puts the AD5270 SDO line in to Hi-Z mode
00103  *  @return none
00104  */
00105 void AD5270::set_SDO_HiZ(void)
00106 {
00107     write_reg(HI_Z_Cmd);
00108     wait_us(2);
00109     write_reg(NO_OP_cmd);
00110 }
00111 
00112 /**
00113  * @brief Set AD5270 SPI frequency
00114  * @param hz - SPI bus frequency in hz
00115  * @return none
00116  */
00117 void AD5270::frequency(int hz)
00118 {
00119     ad5270.frequency(hz);
00120 }
00121 
00122 /**
00123  * @brief Issues AD5270 a command
00124  * @param command - command to be sent
00125  * @param data - (optional)value for the requested command
00126  * @return response form the AD5270
00127  */
00128 uint16_t AD5270::write_cmd(uint8_t command, uint16_t data, bool toggle_cs)
00129 {
00130     /* build 16 bit data to be written - Command + Value */
00131     uint16_t ui16Command = ((command & 0x3C) << 8) | (data & 0x3FF);
00132     return write_reg(ui16Command, toggle_cs);
00133 }
00134 
00135 /**
00136  *  Enables the 50TP memory programming
00137  */
00138 void AD5270::enable_50TP_programming()
00139 {
00140     uint8_t regVal = read_ctrl_reg();
00141     write_cmd(WRITE_CTRL_REG, regVal | PROGRAM_50TP_ENABLE); // RDAC register write protect -  allow update of wiper position through digital interface
00142 }
00143 
00144 /**
00145  *  Stores current RDAC content to the 50TP memory
00146  */
00147 void AD5270::store_50TP()
00148 {
00149     write_cmd(STORE_50TP);
00150     wait_ms(_WRITE_OPERATION_50TP_TIMEOUT);
00151 }
00152 
00153 /**
00154  * Disables the 50TP memory programming
00155  */
00156 void AD5270::disable_50TP_programming()
00157 {
00158     uint8_t regVal = read_ctrl_reg();
00159     write_cmd(WRITE_CTRL_REG, regVal & (~PROGRAM_50TP_ENABLE));
00160 }
00161 
00162 /**
00163  * @brief Writes 16bit data to the AD5270 SPI interface
00164  * @param data to be written
00165  * @return data returned by the AD5270
00166  */
00167 uint16_t AD5270::write_reg(uint16_t data, bool toggle_cs)
00168 {
00169     uint16_t result;
00170     uint8_t upper_byte = (data >> 8) & 0xFF;
00171     uint8_t lower_byte =  data & 0xFF;
00172     ad5270.format(8, _SPI_MODE);
00173     cs = false & toggle_cs;
00174     result  = ((ad5270.write(upper_byte)) << 8);
00175     result |=   ad5270.write(lower_byte);
00176     cs = true & toggle_cs;
00177     return result;
00178 }
00179 
00180 /**
00181  * @brief Gets maximum resistance of the AD5270 digital rheostat
00182  * @return maximum resistance in ohms
00183  */
00184 float AD5270::get_max_resistance()
00185 {
00186     return _max_resistance;
00187 }
00188 
00189 /**
00190  * Writes the wiper register. This includes reading the control register,
00191  * setting write protect off, writing the wiper, and reverting the settings
00192  * to the control reg.
00193  * @param data to be written
00194  */
00195 void AD5270::write_wiper_reg(uint16_t data)
00196 {
00197     uint8_t reg_val = read_ctrl_reg();
00198     write_cmd(WRITE_CTRL_REG, reg_val | RDAC_WRITE_PROTECT); // RDAC register write protect -  allow update of wiper position through digital interface
00199     write_cmd(WRITE_RDAC, data); // write data to the RDAC register
00200     write_cmd(WRITE_CTRL_REG, reg_val); // RDAC register write protect -  allow update of wiper position through digital interface
00201 }
00202 
00203 /**
00204  * Reads the wiper register value
00205  * @return value of the wiper register
00206  */
00207 uint16_t AD5270::read_wiper_reg(void)
00208 {
00209     uint16_t RDAC_val;
00210     write_cmd(READ_RDAC);
00211     wait_us(_REG_OPERATION_TIMEOUT);
00212     RDAC_val = write_cmd(NO_OP);
00213     return RDAC_val;
00214 }
00215 
00216 /**
00217  * Reads the last programmed value of the 50TP memory
00218  * @return last programmed value
00219  */
00220 uint8_t AD5270::read_50TP_last_address(void)
00221 {
00222     uint8_t ret_val;
00223     write_cmd(READ_50TP_ADDRESS);
00224     wait_us(_MEMORY_OPERATION_TIMEOUT);
00225     ret_val = write_cmd(NO_OP);
00226     return ret_val;
00227 }
00228 
00229 /**
00230  * Reads the content of a 50TP memory address
00231  * @param address memory to be read
00232  * @return value stored in the 50TP address
00233  */
00234 uint16_t AD5270::read_50TP_memory(uint8_t address)
00235 {
00236     uint16_t ret_val;
00237     write_cmd(READ_50TP_CONTENTS, address);
00238     wait_us(_MEMORY_OPERATION_TIMEOUT);
00239     ret_val = write_cmd(NO_OP);
00240     return ret_val;
00241 }
00242 
00243 /**
00244  * Writes the control register
00245  * @param data to be written
00246  */
00247 void AD5270::write_ctrl_reg(uint8_t data)
00248 {
00249     write_cmd(WRITE_CTRL_REG, data);
00250 }
00251 
00252 /**
00253  * Reads the control register
00254  * @return value of the control register
00255  */
00256 uint8_t AD5270::read_ctrl_reg(void)
00257 {
00258     uint8_t ret_val;
00259     write_cmd(READ_CTRL_REG);
00260     wait_us(_REG_OPERATION_TIMEOUT);
00261     ret_val = write_cmd(NO_OP);
00262     return ret_val;
00263 }
00264 
00265 /**
00266  * Resets the wiper register value to the data last written in the 50TP
00267  */
00268 void AD5270::reset_RDAC(void)
00269 {
00270     write_cmd(SW_RST);
00271 }
00272 
00273 /**
00274  * Changes the device mode, enabled or shutdown
00275  * @param mode - new mode of the device
00276  */
00277 void AD5270::change_mode(AD5270Modes_t mode)
00278 {
00279     write_cmd(SW_SHUTDOWN, static_cast<uint8_t>(mode));
00280 }
00281 
00282 void AD5270::daisy_chain(uint8_t *buffer, uint8_t size)
00283 {
00284     cs = 0;
00285     for(int i = 0; i < size; i++)
00286         buffer[i] = ad5270.write(buffer[i]);
00287     cs = 1;
00288 }
00289