/*! LTC2498: 24-Bit, 16-Channel Delta Sigma ADCs with Easy Drive Input Current Cancellation @verbatim The LTC2498 is a 16-channel (8-differential) 24-bit No Latency Delta Sigma TM ADC with Easy Drive technology. The patented sampling scheme eliminates dynamic input current errors and the shortcomings of on-chip buffering through automatic cancellation of differential input current. This allows large external source impedances, and rail-to-rail input signals to be directly digitized while maintaining exceptional DC accuracy. SPI DATA FORMAT (MSB First): Byte #1 Byte #2 Data Out : !EOC DMY SIG D28 D27 D26 D25 D24 D23 D22 D21 D20 D19 D18 D17 D16 Data In : 1 0 EN SGL OS A2 A1 A0 EN2 IM FA FB SPD X X X Byte #3 Byte #4 D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 *D3 *D2 *D1 *D0 X X X X X X X X X X X X X X X X !EOC : End of Conversion Bit (Active Low) DMY : Dummy Bit (Always 0) SIG : Sign Bit (1-data positive, 0-data negative) Dx : Data Bits *Dx : Data Bits Below lsb EN : Enable Bit (0-keep previous mode, 1-change mode) SGL : Enable Single-Ended Bit (0-differential, 1-single-ended) OS : ODD/Sign Bit Ax : Address Select Bit IM : Internal Temperature Sensor Bit(0-ADC , 1-Temperature Sensor) Fx : Frequency Rejection Bits SPD : Speed Mode Bit (0-1x, 1-2x) FIMSPD : Double Output Rate Select Bit (0-Normal rate, auto-calibration on, 2x rate, auto_calibration off) Command Byte #1 1 0 EN SGL OS S2 S1 S0 Comments 1 0 0 X X X X X Keep Previous Mode 1 0 1 0 X X X X Differential Mode 1 0 1 1 X X X X Single-Ended Mode Example Code: Read Channel 0 in Single-Ended uint16_t miso_timeout = 1000; adc_command = LTC2498_CH0 | LTC2498_OSR_32768 | LTC2498_SPEED_2X; // Build ADC command for channel 0 // OSR = 32768*2 = 65536 if(LTC2498_EOC_timeout(LTC2498_CS, miso_timeout)) // Check for EOC return; // Exit if timeout is reached LTC2498_read(LTC2498_CS, adc_command, &adc_code); // Throws out last reading if(LTC2498_EOC_timeout(LTC2498_CS, miso_timeout)) // Check for EOC return; // Exit if timeout is reached LTC2498_read(LTC2498_CS, adc_command, &adc_code); // Obtains the current reading and stores to adc_code variable // Convert adc_code to voltage adc_voltage = LTC2498_code_to_voltage(adc_code, LTC2498_lsb, LTC2498_offset_code); @endverbatim http://www.linear.com/product/LTC2498 http://www.linear.com/product/LTC2498#demoboards Copyright 2018(c) Analog Devices, Inc. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. - Neither the name of Analog Devices, Inc. nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. - The use of this software may or may not infringe the patent rights of one or more patent holders. This license does not release you from the requirement that you obtain separate licenses from these patent holders to use this software. - Use of the software either in source or binary form, must be run on or directly connected to an Analog Devices Inc. component. THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /*! @file @ingroup LTC2498 Header for LTC2498: 24-Bit, 16-Channel Delta Sigma ADCs with Selectable Speed/Resolution */ #ifndef LTC2498_H #define LTC2498_H //! Define the SPI CS pin #ifndef LTC2498_CS #define LTC2498_CS QUIKEVAL_CS #endif /*! @name Mode Configuration @{ */ #define LTC2498_KEEP_PREVIOUS_MODE LTC24XX_HS_MULTI_KEEP_PREVIOUS_MODE #define LTC2498_KEEP_PREVIOUS_SPEED_RESOLUTION LTC24XX_HS_MULTI_KEEP_PREVIOUS_SPEED_RESOLUTION #define LTC2498_SPEED_1X LTC24XX_HS_MULTI_SPEED_1X #define LTC2498_SPEED_2X LTC24XX_HS_MULTI_SPEED_2X #define LTC2498_INTERNAL_TEMP 0xC0 // Select rejection frequency - 50 and 60, 50, or 60Hz #define LTC2498_R50 LTC24XX_EZ_MULTI_R50 #define LTC2498_R60 LTC24XX_EZ_MULTI_R60 #define LTC2498_R50_R60 LTC24XX_EZ_MULTI_R55 /*! @} */ /*! @name Single-Ended Channels Configuration @{ */ #define LTC2498_CH0 LTC24XX_MULTI_CH_CH0 #define LTC2498_CH1 LTC24XX_MULTI_CH_CH1 #define LTC2498_CH2 LTC24XX_MULTI_CH_CH2 #define LTC2498_CH3 LTC24XX_MULTI_CH_CH3 #define LTC2498_CH4 LTC24XX_MULTI_CH_CH4 #define LTC2498_CH5 LTC24XX_MULTI_CH_CH5 #define LTC2498_CH6 LTC24XX_MULTI_CH_CH6 #define LTC2498_CH7 LTC24XX_MULTI_CH_CH7 #define LTC2498_CH8 LTC24XX_MULTI_CH_CH8 #define LTC2498_CH9 LTC24XX_MULTI_CH_CH9 #define LTC2498_CH10 LTC24XX_MULTI_CH_CH10 #define LTC2498_CH11 LTC24XX_MULTI_CH_CH11 #define LTC2498_CH12 LTC24XX_MULTI_CH_CH12 #define LTC2498_CH13 LTC24XX_MULTI_CH_CH13 #define LTC2498_CH14 LTC24XX_MULTI_CH_CH14 #define LTC2498_CH15 LTC24XX_MULTI_CH_CH15 /*! @} */ /*! @name Differential Channel Configuration @{ */ #define LTC2498_P0_N1 LTC24XX_MULTI_CH_P0_N1 #define LTC2498_P1_N0 LTC24XX_MULTI_CH_P1_N0 #define LTC2498_P2_N3 LTC24XX_MULTI_CH_P2_N3 #define LTC2498_P3_N2 LTC24XX_MULTI_CH_P3_N2 #define LTC2498_P4_N5 LTC24XX_MULTI_CH_P4_N5 #define LTC2498_P5_N4 LTC24XX_MULTI_CH_P5_N4 #define LTC2498_P6_N7 LTC24XX_MULTI_CH_P6_N7 #define LTC2498_P7_N6 LTC24XX_MULTI_CH_P7_N6 #define LTC2498_P8_N9 LTC24XX_MULTI_CH_P8_N9 #define LTC2498_P9_N8 LTC24XX_MULTI_CH_P9_N8 #define LTC2498_P10_N11 LTC24XX_MULTI_CH_P10_N11 #define LTC2498_P11_N10 LTC24XX_MULTI_CH_P11_N10 #define LTC2498_P12_N13 LTC24XX_MULTI_CH_P12_N13 #define LTC2498_P13_N12 LTC24XX_MULTI_CH_P13_N12 #define LTC2498_P14_N15 LTC24XX_MULTI_CH_P14_N15 #define LTC2498_P15_N14 LTC24XX_MULTI_CH_P15_N14 /*! @} */ /*Commands Construct a channel / resolution control word by bitwise ORing one choice from the channel configuration and one choice from the Oversample ratio configuration. You can also enable 2Xmode, which will increase sample rate by a factor of 2 but introduce an offset of up to 2mV (refer to datasheet EC table.) Example - read channel 3 single-ended at OSR2048, with 2X mode enabled. adc_command = (LTC2498_CH3 | LTC2498_SPEED_2X; */ //! Checks for EOC with a specified timeout. //! @return Returns 0=successful, 1=unsuccessful (exceeded timeout) int8_t LTC2498_EOC_timeout(uint8_t cs, //!< Chip Select pin uint16_t miso_timeout //!< Timeout (in milliseconds) ); //! Reads from LTC2498. void LTC2498_read(uint8_t cs, //!< Chip select uint8_t adc_command_high, //!< High byte command written to LTC2498 uint8_t adc_command_low, //!< Low byte command written to LTC2498 int32_t *adc_code //!< 4 byte conversion code read from LTC2498 ); //! Calculates the voltage corresponding to an adc code, given the reference (in volts) //! @return Returns voltage calculated from ADC code. float LTC2498_code_to_voltage(int32_t adc_code, //!< Code read from adc float vref //!< VRef (in volts) ); #endif // LTC2498_H