Rohan Gurav / Mbed OS Sean_AdiSense1000_V21

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Fork of AdiSense1000_V21 by Sean Wilson

doc/key_topics.md@19:a6d4bdcffb84, 2018-01-08 (annotated)

Committer:
kevin1990
Date:
Mon Jan 08 16:32:34 2018 +0000
Revision:
19:a6d4bdcffb84
v1.0_RC4 Release

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kevin1990 19:a6d4bdcffb84 1 Key Topics
kevin1990 19:a6d4bdcffb84 2 ==========
kevin1990 19:a6d4bdcffb84 3
kevin1990 19:a6d4bdcffb84 4 [TOC]
kevin1990 19:a6d4bdcffb84 5
kevin1990 19:a6d4bdcffb84 6 # Register Interface {#registerinterface}
kevin1990 19:a6d4bdcffb84 7 The ADI Sense module provides a register-style interface for the purpose
kevin1990 19:a6d4bdcffb84 8 of exchanging configuration, status, and data with the host application
kevin1990 19:a6d4bdcffb84 9 processor.
kevin1990 19:a6d4bdcffb84 10
kevin1990 19:a6d4bdcffb84 11 ## Overview {#registerinterface_overview}
kevin1990 19:a6d4bdcffb84 12 The registers can be divided broadly into the following categories:
kevin1990 19:a6d4bdcffb84 13 * Command input register
kevin1990 19:a6d4bdcffb84 14 - This special register is used to issue commands to the module.
kevin1990 19:a6d4bdcffb84 15 - New commands are typically ignored until the running command
kevin1990 19:a6d4bdcffb84 16 has completed (as indicated via the Status registers)
kevin1990 19:a6d4bdcffb84 17 * Configuration input registers
kevin1990 19:a6d4bdcffb84 18 - Configuration registers are used to specify configuration parameters
kevin1990 19:a6d4bdcffb84 19 for use by the module, typically specifying details such as operating
kevin1990 19:a6d4bdcffb84 20 mode, sensor information, limits, and many other options.
kevin1990 19:a6d4bdcffb84 21 - Changes to configuration input registers are typically ignored until a
kevin1990 19:a6d4bdcffb84 22 command is issued to "apply" the configuration on the device.
kevin1990 19:a6d4bdcffb84 23 * Status output registers
kevin1990 19:a6d4bdcffb84 24 - Status information is provided by the module via these read-only registers
kevin1990 19:a6d4bdcffb84 25 - Dedicated output signals (e.g. ERROR and ALERT) may be linked with this
kevin1990 19:a6d4bdcffb84 26 status information
kevin1990 19:a6d4bdcffb84 27 - The host application processor may acknowledge and reset/clear the status
kevin1990 19:a6d4bdcffb84 28 indicators by reading the relevant status registers. The status indicators
kevin1990 19:a6d4bdcffb84 29 will be set again if the underlying condition is subsequently detected again
kevin1990 19:a6d4bdcffb84 30 * Data output registers
kevin1990 19:a6d4bdcffb84 31 - Measurement data samples produced by the module are typically accessed via
kevin1990 19:a6d4bdcffb84 32 a FIFO-style register which may be read repeatedly until all available data
kevin1990 19:a6d4bdcffb84 33 has been consumed.
kevin1990 19:a6d4bdcffb84 34 - Data samples are provided in a pre-determined format according to the
kevin1990 19:a6d4bdcffb84 35 measurement mode, and typically comprise a processed measurement value,
kevin1990 19:a6d4bdcffb84 36 status flags, measurement channel identifier and, optionally, the raw
kevin1990 19:a6d4bdcffb84 37 (unprocessed) data sample retrieved from the sensor input channel.
kevin1990 19:a6d4bdcffb84 38 * Keyhole access registers
kevin1990 19:a6d4bdcffb84 39 - Access to large internal memory regions within the module is typically
kevin1990 19:a6d4bdcffb84 40 provided via an pair of "keyhole" registers, consisting of an address
kevin1990 19:a6d4bdcffb84 41 register and a data register. An address (i.e. an starting offset within
kevin1990 19:a6d4bdcffb84 42 the region) must first be written to the address register, then the
kevin1990 19:a6d4bdcffb84 43 companion data register may be accessed repeatedly to read/write data to
kevin1990 19:a6d4bdcffb84 44 the corresponding region. The address is automatically incremented with
kevin1990 19:a6d4bdcffb84 45 each access to the data register, so that data can be transferred in a
kevin1990 19:a6d4bdcffb84 46 single burst for efficiency.
kevin1990 19:a6d4bdcffb84 47
kevin1990 19:a6d4bdcffb84 48 # Configuration {#configuration}
kevin1990 19:a6d4bdcffb84 49 The ADI Sense module is a flexible measurement processor which must be
kevin1990 19:a6d4bdcffb84 50 configured via the [register interface](@ref #registerinterface) before it
kevin1990 19:a6d4bdcffb84 51 can be used to acquire data from its external sensor inputs.
kevin1990 19:a6d4bdcffb84 52
kevin1990 19:a6d4bdcffb84 53 ## Overview {#configuration_overview}
kevin1990 19:a6d4bdcffb84 54 A configuration consists of the following elements:
kevin1990 19:a6d4bdcffb84 55 * Global configuration register settings, such as:
kevin1990 19:a6d4bdcffb84 56 - Operating modes
kevin1990 19:a6d4bdcffb84 57 - Power configuration
kevin1990 19:a6d4bdcffb84 58 - Measurement cycle timing
kevin1990 19:a6d4bdcffb84 59 - External reference values
kevin1990 19:a6d4bdcffb84 60 * Channel-specific register settings, such as:
kevin1990 19:a6d4bdcffb84 61 - measurement count
kevin1990 19:a6d4bdcffb84 62 - connected sensor type
kevin1990 19:a6d4bdcffb84 63 - sensor configuration details
kevin1990 19:a6d4bdcffb84 64 - settling time
kevin1990 19:a6d4bdcffb84 65 - filter options
kevin1990 19:a6d4bdcffb84 66 - threshold limits
kevin1990 19:a6d4bdcffb84 67 - calibration adjustments
kevin1990 19:a6d4bdcffb84 68 * Optional user-defined analog sensor linearisation data
kevin1990 19:a6d4bdcffb84 69 - used to compensate for inherent non-linear characteristics of analog sensors
kevin1990 19:a6d4bdcffb84 70 - supplied via a Look-Up Table data structure with a specific format
kevin1990 19:a6d4bdcffb84 71 - allows the user to leverage the data acquisition and processing features
kevin1990 19:a6d4bdcffb84 72 of the ADI Sense module for use with non-standard or unsupported sensors
kevin1990 19:a6d4bdcffb84 73
kevin1990 19:a6d4bdcffb84 74 ## Configuration data structure {#configuration_data}
kevin1990 19:a6d4bdcffb84 75 Although the module can be configured and managed directly via the
kevin1990 19:a6d4bdcffb84 76 [register interface](@ref #registerinterface), the ADI Sense Host Library
kevin1990 19:a6d4bdcffb84 77 provides a level of abstraction above this which allows a more simplified
kevin1990 19:a6d4bdcffb84 78 programming paradigm for the device.
kevin1990 19:a6d4bdcffb84 79
kevin1990 19:a6d4bdcffb84 80 A single C-language configuration data structure can be used to define all
kevin1990 19:a6d4bdcffb84 81 configuration values for the ADI Sense module. This can be passed to the
kevin1990 19:a6d4bdcffb84 82 relevant ADI Sense Host Library API functions, which will do the work of
kevin1990 19:a6d4bdcffb84 83 translating the configuration details into the appropriate register values
kevin1990 19:a6d4bdcffb84 84 and sending them to the module via its host communication interface.
kevin1990 19:a6d4bdcffb84 85
kevin1990 19:a6d4bdcffb84 86 The [examples](doc/examples.md) provided with the ADI Sense Host Library
kevin1990 19:a6d4bdcffb84 87 demonstrate this configuration method. Individual configurations are stored
kevin1990 19:a6d4bdcffb84 88 and compiled as .c files, and a configuration may be selected and loaded by
kevin1990 19:a6d4bdcffb84 89 the application code. Note that only the essential configuration fields are
kevin1990 19:a6d4bdcffb84 90 filled, depending on the specific sensor configuration and operating mode
kevin1990 19:a6d4bdcffb84 91 required.
kevin1990 19:a6d4bdcffb84 92
kevin1990 19:a6d4bdcffb84 93 ## Loading and Applying a configuration {#configuration_loading}
kevin1990 19:a6d4bdcffb84 94 Configuration data must first be loaded via the @ref adi_sense_SetConfig API
kevin1990 19:a6d4bdcffb84 95 function - which updates the registers on the module according to the supplied
kevin1990 19:a6d4bdcffb84 96 configuration details - and then applied by calling the @ref
kevin1990 19:a6d4bdcffb84 97 adi_sense_ApplyConfigUpdates function which issues a special command to instruct
kevin1990 19:a6d4bdcffb84 98 the module to apply the new configuration. If user-defined linearisation data
kevin1990 19:a6d4bdcffb84 99 is also required, this must also be loaded via the @ref
kevin1990 19:a6d4bdcffb84 100 adi_sense_1000_SetLutData function _before_ applying the new configuration.
kevin1990 19:a6d4bdcffb84 101
kevin1990 19:a6d4bdcffb84 102 To avoid loading the configuration details to the module every time it is
kevin1990 19:a6d4bdcffb84 103 powered on, it is possible to save it to non-volatile memory on the module
kevin1990 19:a6d4bdcffb84 104 using @ref adi_sense_SaveConfig and @ref adi_sense_SaveLutData. The saved
kevin1990 19:a6d4bdcffb84 105 configuration is automatically restored by default when the module is
kevin1990 19:a6d4bdcffb84 106 subsequently reset or powered on, and can also be reloaded on demand if required
kevin1990 19:a6d4bdcffb84 107 using the @ref adi_sense_RestoreConfig and @ref adi_sense_RestoreLutData
kevin1990 19:a6d4bdcffb84 108 functions. Note that, in all cases, @ref adi_sense_ApplyConfigUpdates _must_
kevin1990 19:a6d4bdcffb84 109 be called to instruct the module to apply the configuration before will be used.
kevin1990 19:a6d4bdcffb84 110
kevin1990 19:a6d4bdcffb84 111 Once a valid configuration has been loaded and applied, the user may issue
kevin1990 19:a6d4bdcffb84 112 commands to the module to initiate measurement cycles, internal calibration, or
kevin1990 19:a6d4bdcffb84 113 diagnostic routines (all of which depend on a valid configuration being applied
kevin1990 19:a6d4bdcffb84 114 in advance).
kevin1990 19:a6d4bdcffb84 115
kevin1990 19:a6d4bdcffb84 116 ## Configuration errors {#configuration_errors}
kevin1990 19:a6d4bdcffb84 117 Attempts to load invalid configuration details will be flagged via the relevant
kevin1990 19:a6d4bdcffb84 118 status registers and signals. After calling @ref adi_sense_ApplyConfigUpdates,
kevin1990 19:a6d4bdcffb84 119 it is advisable to check the status of the module by calling @ref
kevin1990 19:a6d4bdcffb84 120 adi_sense_GetStatus and examining the relevant status information returned from
kevin1990 19:a6d4bdcffb84 121 the module. Subsequent commands issued to the module may not execute correctly
kevin1990 19:a6d4bdcffb84 122 in the presence of unresolved configuration errors.
kevin1990 19:a6d4bdcffb84 123
kevin1990 19:a6d4bdcffb84 124 # Measurement Cycles {#measurementcycles}
kevin1990 19:a6d4bdcffb84 125 ## Overview {#measurementcycles_overview}
kevin1990 19:a6d4bdcffb84 126 Conversions are carried out sequentially across each of the enabled channels in
kevin1990 19:a6d4bdcffb84 127 a predictable pattern which has a defined order and user-specified number of
kevin1990 19:a6d4bdcffb84 128 conversions per channel. This is typically referred to as the _Measurement
kevin1990 19:a6d4bdcffb84 129 Sequence_.
kevin1990 19:a6d4bdcffb84 130
kevin1990 19:a6d4bdcffb84 131 A _Measurement Cycle_ essentially consists of a single _Measurement Sequence_
kevin1990 19:a6d4bdcffb84 132 which may be repeated at specified time intervals.
kevin1990 19:a6d4bdcffb84 133
kevin1990 19:a6d4bdcffb84 134 The configuration parameters required to define the Measurement Cycle and
kevin1990 19:a6d4bdcffb84 135 Sequence are as follows:
kevin1990 19:a6d4bdcffb84 136 * Cycle interval time (specified in microseconds/milliseconds/seconds)
kevin1990 19:a6d4bdcffb84 137 * For each enabled sensor input channel:
kevin1990 19:a6d4bdcffb84 138 - Number of conversions-per-cycle
kevin1990 19:a6d4bdcffb84 139 - Extra settling time (specified in microseconds)
kevin1990 19:a6d4bdcffb84 140
kevin1990 19:a6d4bdcffb84 141 In addition to the cycle time, the following operating modes dictate when and
kevin1990 19:a6d4bdcffb84 142 how many cycles should be executed:
kevin1990 19:a6d4bdcffb84 143 * **Single-Cycle Mode**
kevin1990 19:a6d4bdcffb84 144 - Executes a single Measurement Cycle and stops
kevin1990 19:a6d4bdcffb84 145 * **Continuous Mode**
kevin1990 19:a6d4bdcffb84 146 - Executes Measurement Cycles continuously until stopped by the host
kevin1990 19:a6d4bdcffb84 147 application processor
kevin1990 19:a6d4bdcffb84 148 * **Multi-Cycle Mode**
kevin1990 19:a6d4bdcffb84 149 - Executes a specified number (burst) of Measurement Cycles and stores the
kevin1990 19:a6d4bdcffb84 150 results in a buffer for retrieval by the host.
kevin1990 19:a6d4bdcffb84 151 - Repeats this indefinitely at specified intervals (multi-cycle burst
kevin1990 19:a6d4bdcffb84 152 interval) until stopped by the host application processor.
kevin1990 19:a6d4bdcffb84 153
kevin1990 19:a6d4bdcffb84 154 ## Executing Measurement Cycles {#measurementcycles_executing}
kevin1990 19:a6d4bdcffb84 155 Once a valid configuration is loaded (see @ref #configuration),
kevin1990 19:a6d4bdcffb84 156 Measurement Cycles are initiated by the host application processor via @ref
kevin1990 19:a6d4bdcffb84 157 adi_sense_StartMeasurement, and may be stopped if necessary via @ref
kevin1990 19:a6d4bdcffb84 158 adi_sense_StopMeasurement. These functions issue the relevant commands to the
kevin1990 19:a6d4bdcffb84 159 ADI Sense module via its dedicate command register.
kevin1990 19:a6d4bdcffb84 160
kevin1990 19:a6d4bdcffb84 161 Certain auxiliary tasks may also be carried out internally by the module on a
kevin1990 19:a6d4bdcffb84 162 per-cycle basis, such as Calibration and Diagnostics. These are discussed in
kevin1990 19:a6d4bdcffb84 163 in later sections below.
kevin1990 19:a6d4bdcffb84 164
kevin1990 19:a6d4bdcffb84 165 ## Sequence Order {#measurementcycles_sequence}
kevin1990 19:a6d4bdcffb84 166 The sequence is constructed according to which channels are enabled and how many
kevin1990 19:a6d4bdcffb84 167 measurements must be performed per channel. The arrangement is similar to
kevin1990 19:a6d4bdcffb84 168 round-robin scheduling - a measurement is carried out on each enabled channel, in
kevin1990 19:a6d4bdcffb84 169 ascending channel order, and then the loop is repeated until the requested number
kevin1990 19:a6d4bdcffb84 170 of measurements on each channel has been satisfied.
kevin1990 19:a6d4bdcffb84 171
kevin1990 19:a6d4bdcffb84 172 For example, lets say channels [0, 3, 4, 5] are enabled, with measurementsPerCycle
kevin1990 19:a6d4bdcffb84 173 set as follows:
kevin1990 19:a6d4bdcffb84 174
kevin1990 19:a6d4bdcffb84 175 channelId | measurementsPerCycle
kevin1990 19:a6d4bdcffb84 176 --------- | --------------------
kevin1990 19:a6d4bdcffb84 177 CJC_1 | 4
kevin1990 19:a6d4bdcffb84 178 SENSOR_0 | 2
kevin1990 19:a6d4bdcffb84 179 I2C_1 | 3
kevin1990 19:a6d4bdcffb84 180 SPI_0 | 1
kevin1990 19:a6d4bdcffb84 181
kevin1990 19:a6d4bdcffb84 182 The length of the sequence would be 10 measurements in total, and the order in
kevin1990 19:a6d4bdcffb84 183 which the channel measurements appear in the sequence would look like this:
kevin1990 19:a6d4bdcffb84 184
kevin1990 19:a6d4bdcffb84 185 | **CJC_1** | **SENSOR_0** | **I2C_1** | **SPI_0** | **CJC_1** | **SENSOR_0** | **I2C_1** | **CJC_1** | **I2C_1** | **CJC_1** |
kevin1990 19:a6d4bdcffb84 186
kevin1990 19:a6d4bdcffb84 187 When measurement data samples are retrieved from the ADI Sense by the host
kevin1990 19:a6d4bdcffb84 188 application, this is the order in which those data samples will appear.
kevin1990 19:a6d4bdcffb84 189
kevin1990 19:a6d4bdcffb84 190 The ADI Sense 1000 provides up to 13 measurement channels, and allows a maximum
kevin1990 19:a6d4bdcffb84 191 measurementsPerCycle of 128, so a single cycle can produce a maximum of 1664
kevin1990 19:a6d4bdcffb84 192 measurements. In other words, the maximum length of the sequence is 1664.
kevin1990 19:a6d4bdcffb84 193
kevin1990 19:a6d4bdcffb84 194 ## Sequence Timing {#measurementcycles_timing}
kevin1990 19:a6d4bdcffb84 195 The timing of each measurement within the sequence depends on a number of factors:
kevin1990 19:a6d4bdcffb84 196 * **Settling time**
kevin1990 19:a6d4bdcffb84 197 - A settling time is applied when switching between each channel (unless only
kevin1990 19:a6d4bdcffb84 198 a single channel in the sequence), particularly to allow the analog
kevin1990 19:a6d4bdcffb84 199 front-end circuit to stabilise before a conversion is performed.
kevin1990 19:a6d4bdcffb84 200 - Each channel is subject to a minimum settling time (e.g. 500 microseconds)
kevin1990 19:a6d4bdcffb84 201 - Additional settling time can be configured per-channel if required
kevin1990 19:a6d4bdcffb84 202 - As the analog sensor channels are multi-plexed into a single physical input
kevin1990 19:a6d4bdcffb84 203 channel, with different front-end circuit configurations for each, the
kevin1990 19:a6d4bdcffb84 204 settling and conversion of the analog channels must be done one-at-a-time in
kevin1990 19:a6d4bdcffb84 205 series. Their settling time starts only when the channel is reached in the
kevin1990 19:a6d4bdcffb84 206 sequence.
kevin1990 19:a6d4bdcffb84 207 - Digital sensors operate independently, and so are activated in parallel to
kevin1990 19:a6d4bdcffb84 208 other sensors. Consequently, their settling time may start at the start of
kevin1990 19:a6d4bdcffb84 209 a cycle, or immediately after a previous conversion result has been obtained
kevin1990 19:a6d4bdcffb84 210 from the sensor.
kevin1990 19:a6d4bdcffb84 211 * **Conversion time**
kevin1990 19:a6d4bdcffb84 212 - Once the settling time has passed, a conversion is initiated to obtain a raw
kevin1990 19:a6d4bdcffb84 213 measurement value from the sensor input.
kevin1990 19:a6d4bdcffb84 214 - The time required for the conversion may be influenced by factors such as
kevin1990 19:a6d4bdcffb84 215 filter configuration (in the case of analog channels) or specific digital
kevin1990 19:a6d4bdcffb84 216 sensor performance characteristics and configuration options.
kevin1990 19:a6d4bdcffb84 217 * **Processing time**
kevin1990 19:a6d4bdcffb84 218 - Once the raw conversion result is obtained, it is subjected to further
kevin1990 19:a6d4bdcffb84 219 processing to apply correction for non-linear sensors, calibration
kevin1990 19:a6d4bdcffb84 220 adjustments, and conversion into standard measurement units
kevin1990 19:a6d4bdcffb84 221 - The processing time varies depending on the sensor type and correction
kevin1990 19:a6d4bdcffb84 222 algorithms to be applied, but a standard budget of processing time (e.g.
kevin1990 19:a6d4bdcffb84 223 500 microseconds) is allocated to each channel to produce consistent and
kevin1990 19:a6d4bdcffb84 224 predictable time separation between the measurement results.
kevin1990 19:a6d4bdcffb84 225
kevin1990 19:a6d4bdcffb84 226 So, to summarise, the distinct phases for each measurement on each channel
kevin1990 19:a6d4bdcffb84 227 typically look like this:
kevin1990 19:a6d4bdcffb84 228
kevin1990 19:a6d4bdcffb84 229 **settling** > **conversion** > **processing** > **publishing**
kevin1990 19:a6d4bdcffb84 230
kevin1990 19:a6d4bdcffb84 231 Taking the sequence example in the previous section, let's assume a base
kevin1990 19:a6d4bdcffb84 232 settling time (_Ts_) and processing time (_Tp_) of 500 microseconds for each channel
kevin1990 19:a6d4bdcffb84 233 and the following variable timing parameters _Te_ and _Tc_ (in units of microseconds):
kevin1990 19:a6d4bdcffb84 234
kevin1990 19:a6d4bdcffb84 235 channelId | extraSettlingTime (_Te_) | conversionTime (_Tc_) | sum (_Ts_ + _Te_ + _Tc_ + _Tp_) | measurementsPerCycle | total
kevin1990 19:a6d4bdcffb84 236 --------- | ------------------------ | --------------------- | ------------------------------- | -------------------- | -----
kevin1990 19:a6d4bdcffb84 237 CJC_1 | 4000 | 50000 | 55000 | 4 | 220000
kevin1990 19:a6d4bdcffb84 238 SENSOR_0 | 1000 | 50000 | 52000 | 2 | 104000
kevin1990 19:a6d4bdcffb84 239 I2C_1 | 20000 | 1000 | 22000 | 3 | 66000
kevin1990 19:a6d4bdcffb84 240 SPI_0 | 0 | 800 | 1800 | 1 | 1800
kevin1990 19:a6d4bdcffb84 241
kevin1990 19:a6d4bdcffb84 242 To clarify: _Te_ above comes directly from the channel configuration. _Tc_, however,
kevin1990 19:a6d4bdcffb84 243 is dictated by the sensor and its configuration.
kevin1990 19:a6d4bdcffb84 244
kevin1990 19:a6d4bdcffb84 245 The minimum time required for the cycle to complete is, in the above example,
kevin1990 19:a6d4bdcffb84 246 391800 microseconds.
kevin1990 19:a6d4bdcffb84 247
kevin1990 19:a6d4bdcffb84 248 If the selected operating mode is Continuous or Multi-Cycle mode, the
kevin1990 19:a6d4bdcffb84 249 configuration must also specify the interval between successive cycles
kevin1990 19:a6d4bdcffb84 250 (cycleInterval). If this is less than the actual time required to
kevin1990 19:a6d4bdcffb84 251 complete the cycle, the next cycle will start immediately after the
kevin1990 19:a6d4bdcffb84 252 completion of the previous one; if it is more, there will be a delay
kevin1990 19:a6d4bdcffb84 253 until the next cycle is started.
kevin1990 19:a6d4bdcffb84 254
kevin1990 19:a6d4bdcffb84 255 ## Measurement Results storage and retrieval {#measurementcycles_publishing}
kevin1990 19:a6d4bdcffb84 256 As part of module configuration, a data-ready mode must be selected to decide
kevin1990 19:a6d4bdcffb84 257 how measurements results are made available and retained for consuming by the
kevin1990 19:a6d4bdcffb84 258 host application processor:
kevin1990 19:a6d4bdcffb84 259
kevin1990 19:a6d4bdcffb84 260 * **Per-Conversion**
kevin1990 19:a6d4bdcffb84 261 - In this mode, each measurement result (a.k.a. data sample) is made available
kevin1990 19:a6d4bdcffb84 262 as soon as it is ready.
kevin1990 19:a6d4bdcffb84 263 - Only a single result is stored, and it is overwritten when the next
kevin1990 19:a6d4bdcffb84 264 measurement result becomes ready. Only the latest result is retained.
kevin1990 19:a6d4bdcffb84 265 - The host application processor must, therefore, consume each single
kevin1990 19:a6d4bdcffb84 266 measurement result (by reading the DATA_FIFO register) as soon as the
kevin1990 19:a6d4bdcffb84 267 result becomes available.
kevin1990 19:a6d4bdcffb84 268 * **Per-Cycle**
kevin1990 19:a6d4bdcffb84 269 - In this mode, the measurement results from a full cycle (10 data samples,
kevin1990 19:a6d4bdcffb84 270 in the example above) are made available only when the measurement cycle is
kevin1990 19:a6d4bdcffb84 271 complete.
kevin1990 19:a6d4bdcffb84 272 - The results are overwritten when the next measurement cycle (if any)
kevin1990 19:a6d4bdcffb84 273 is completed.
kevin1990 19:a6d4bdcffb84 274 - The host application processor must consume the measurement results in a
kevin1990 19:a6d4bdcffb84 275 batch as soon as they become available.
kevin1990 19:a6d4bdcffb84 276 * **Per-Multicycle-Burst**
kevin1990 19:a6d4bdcffb84 277 - In this mode, the measurement results from a burst of measurement cycles
kevin1990 19:a6d4bdcffb84 278 are made available only when thise measurement cycles are completed.
kevin1990 19:a6d4bdcffb84 279 - The results are overwritten when the next burst of measurement cycles
kevin1990 19:a6d4bdcffb84 280 are completed.
kevin1990 19:a6d4bdcffb84 281 - The host application processor must consume the measurement results in a
kevin1990 19:a6d4bdcffb84 282 batch as soon as they become available.
kevin1990 19:a6d4bdcffb84 283 - Note that this data-ready mode is only available when the Multi-Cycle
kevin1990 19:a6d4bdcffb84 284 operating mode is also selected.
kevin1990 19:a6d4bdcffb84 285
kevin1990 19:a6d4bdcffb84 286 When new measurement results are ready for retrieval, the DRDY output signal
kevin1990 19:a6d4bdcffb84 287 is asserted. The host application may check this signal continuously, or attach
kevin1990 19:a6d4bdcffb84 288 an interrupt notification to this signal, to ensure that measurement results are
kevin1990 19:a6d4bdcffb84 289 retrieved in a timely fashion before they are subsequently overwritten by the
kevin1990 19:a6d4bdcffb84 290 next conversion/cycle. Alternatively, the host application may also read the
kevin1990 19:a6d4bdcffb84 291 STATUS register to check the DRDY status indicator.
kevin1990 19:a6d4bdcffb84 292
kevin1990 19:a6d4bdcffb84 293 The ADI Sense Host Library API provides the following functions which are
kevin1990 19:a6d4bdcffb84 294 relevant for data retrieval:
kevin1990 19:a6d4bdcffb84 295 * @ref adi_sense_RegisterGpioCallback for recieving DRDY interrupt notifications
kevin1990 19:a6d4bdcffb84 296 * @ref adi_sense_GetGpioState for polling the state of the DRDY signal
kevin1990 19:a6d4bdcffb84 297 * @ref adi_sense_GetStatus for reading the module status registers
kevin1990 19:a6d4bdcffb84 298 * @ref adi_sense_GetData for retrieveing the measurement results from the module
kevin1990 19:a6d4bdcffb84 299
kevin1990 19:a6d4bdcffb84 300 The @ref adi_sense_1000_GetDataReadyModeInfo API function, specific to the ADI
kevin1990 19:a6d4bdcffb84 301 Sense 1000, is also useful for obtaining information on the number of
kevin1990 19:a6d4bdcffb84 302 measurement results to expect when the DRDY indicator is asserted, based on the
kevin1990 19:a6d4bdcffb84 303 operating and data-ready mode configuration settings currently set in the module
kevin1990 19:a6d4bdcffb84 304 registers.
kevin1990 19:a6d4bdcffb84 305
kevin1990 19:a6d4bdcffb84 306 # Calibration {#calibration}
kevin1990 19:a6d4bdcffb84 307 The ADI Sense module incorporates a number of calibration measures to ensure
kevin1990 19:a6d4bdcffb84 308 the accuracy of measurement results, described in the following sections. These
kevin1990 19:a6d4bdcffb84 309 mostly pertain to the analog measurement channels, but some provisions are also
kevin1990 19:a6d4bdcffb84 310 included for calibration of digital sensors.
kevin1990 19:a6d4bdcffb84 311
kevin1990 19:a6d4bdcffb84 312 ## Factory calibration {#calibration_factory}
kevin1990 19:a6d4bdcffb84 313 Calibration is performed during factory production for error introduced by
kevin1990 19:a6d4bdcffb84 314 components (e.g. resistors, switches) present on the signal paths of the
kevin1990 19:a6d4bdcffb84 315 module's analog front-end. Calibration offset and gain values are calculated
kevin1990 19:a6d4bdcffb84 316 and stored in non-volatile memory within the module as part of the production
kevin1990 19:a6d4bdcffb84 317 process. These are applied automatically without intervention from the host
kevin1990 19:a6d4bdcffb84 318 application.
kevin1990 19:a6d4bdcffb84 319
kevin1990 19:a6d4bdcffb84 320 ## Internal auto-calibration {#calibration_internal}
kevin1990 19:a6d4bdcffb84 321 The high-accuracy ADC incorporated within the ADI Sense module includes
kevin1990 19:a6d4bdcffb84 322 internal calibration functions to assist in removing offset or gain errors
kevin1990 19:a6d4bdcffb84 323 internal to that ADC. As this is a time-consuming process, it is invoked
kevin1990 19:a6d4bdcffb84 324 only in the following circumstances:
kevin1990 19:a6d4bdcffb84 325 * The host application issues a self-calibration command (@ref
kevin1990 19:a6d4bdcffb84 326 adi_sense_RunCalibration)
kevin1990 19:a6d4bdcffb84 327 * The host application updates the module configuration and the module
kevin1990 19:a6d4bdcffb84 328 determines, based on the configuration changes, that re-calibration is
kevin1990 19:a6d4bdcffb84 329 required. In this case, the calibration is carried out at the point
kevin1990 19:a6d4bdcffb84 330 where the new configuration settings are applied (@ref
kevin1990 19:a6d4bdcffb84 331 adi_sense_ApplyConfigUpdates)
kevin1990 19:a6d4bdcffb84 332
kevin1990 19:a6d4bdcffb84 333 In all cases, a valid configuration must be set and it used as part of the
kevin1990 19:a6d4bdcffb84 334 calibration process. External sensors and reference circuits must be
kevin1990 19:a6d4bdcffb84 335 connected for calibration to work correctly.
kevin1990 19:a6d4bdcffb84 336
kevin1990 19:a6d4bdcffb84 337 ## User calibration {#calibration_user}
kevin1990 19:a6d4bdcffb84 338 Additional gain and offset correction parameters may be specified per-channel as
kevin1990 19:a6d4bdcffb84 339 part of the module configuration. These are applied as a final step to each
kevin1990 19:a6d4bdcffb84 340 measurement result from the channel during the final stages of processing before
kevin1990 19:a6d4bdcffb84 341 the data sample is made available to the host processor.
kevin1990 19:a6d4bdcffb84 342
kevin1990 19:a6d4bdcffb84 343 # Diagnostics {#diagnostics}
kevin1990 19:a6d4bdcffb84 344 The ADC within the ADI Sense module includes a range of sophisticated diagnostic
kevin1990 19:a6d4bdcffb84 345 features to automatically detect error conditions such as under-/over-voltage on
kevin1990 19:a6d4bdcffb84 346 analog input signals, supply voltage errors, reference detection errors and more.
kevin1990 19:a6d4bdcffb84 347 These are enabled by default and, if triggered, will result in an ERROR or ALERT
kevin1990 19:a6d4bdcffb84 348 signal being asserted by the module. Diagnostic status can be queried via the
kevin1990 19:a6d4bdcffb84 349 module status registers (@ref adi_sense_GetStatus).
kevin1990 19:a6d4bdcffb84 350
kevin1990 19:a6d4bdcffb84 351 Additional diagnostic tests may be executed by the module to detect additional
kevin1990 19:a6d4bdcffb84 352 error conditions such as a disconnected or mis-wired sensor. These tests are
kevin1990 19:a6d4bdcffb84 353 typically time-consuming, and so are carried out only if selected by the user:
kevin1990 19:a6d4bdcffb84 354 * Sensor diagnostics may be requested by executing a dedicated diagnostics
kevin1990 19:a6d4bdcffb84 355 command (@ref adi_sense_RunDiagnostics)
kevin1990 19:a6d4bdcffb84 356 * Sensor diagnostics may be optionally executed at the start of each measurement
kevin1990 19:a6d4bdcffb84 357 cycle, at a frequency determined by the user through the configuration
kevin1990 19:a6d4bdcffb84 358 parameters (see @ref ADI_SENSE_1000_DIAGNOSTICS_CONFIG)
kevin1990 19:a6d4bdcffb84 359
kevin1990 19:a6d4bdcffb84 360 # Sensor Linearisation {#linearisation}
kevin1990 19:a6d4bdcffb84 361 Analog sensors typically produce an output which is not completely linear or
kevin1990 19:a6d4bdcffb84 362 directly proportional with respect to their input. Different sensor types
kevin1990 19:a6d4bdcffb84 363 generally have different linearity characteristics, each requiring different
kevin1990 19:a6d4bdcffb84 364 correction methods or coefficients for accurate translation of the sensor output
kevin1990 19:a6d4bdcffb84 365 back to the corresponding input. Typical methods include use of linearisation
kevin1990 19:a6d4bdcffb84 366 formulae (e.g. polynomial equations with variable coefficients), or tables of
kevin1990 19:a6d4bdcffb84 367 sample input values and their corresponding outputs which can be used with
kevin1990 19:a6d4bdcffb84 368 interpolation to perform the translation.
kevin1990 19:a6d4bdcffb84 369
kevin1990 19:a6d4bdcffb84 370 The ADI Sense module performs linearisation and calibration correction of the
kevin1990 19:a6d4bdcffb84 371 analog sensor measurements, and incorporates the linearisation functions
kevin1990 19:a6d4bdcffb84 372 complete with coefficients or translation tables for a range of supported sensor
kevin1990 19:a6d4bdcffb84 373 types. On the ADI Sense 1000, for example, measurement results from any
kevin1990 19:a6d4bdcffb84 374 [sensor types](@ref ADI_SENSE_1000_ADC_SENSOR_TYPE) named with the
kevin1990 19:a6d4bdcffb84 375 "_L1" suffix or with a specific sensor model name (e.g. @ref
kevin1990 19:a6d4bdcffb84 376 ADI_SENSE_1000_ADC_SENSOR_VOLTAGE_PRESSURE_AMPHENOL_NPA300X) will be
kevin1990 19:a6d4bdcffb84 377 automatically linearised using built-in linearisation functions and coefficients
kevin1990 19:a6d4bdcffb84 378 or translation tables.
kevin1990 19:a6d4bdcffb84 379
kevin1990 19:a6d4bdcffb84 380 It is also possible to have ADI Sense perform linearisation on other sensor
kevin1990 19:a6d4bdcffb84 381 types. A range of [sensor type IDs](@ref ADI_SENSE_1000_ADC_SENSOR_TYPE) named
kevin1990 19:a6d4bdcffb84 382 with an "_L2" suffix are reserved for this purpose. By specifying one of these
kevin1990 19:a6d4bdcffb84 383 sensor types, and by providing the necessary linearisation information for that
kevin1990 19:a6d4bdcffb84 384 sensor type as part of a "look-up table" data structure loaded via the @ref
kevin1990 19:a6d4bdcffb84 385 adi_sense_1000_SetLutData API function, the ADI Sense module can be extended to
kevin1990 19:a6d4bdcffb84 386 work with sensor variants which require a different linearisation what is
kevin1990 19:a6d4bdcffb84 387 already provided through built-in methods. Linearisation data may be provided
kevin1990 19:a6d4bdcffb84 388 in the form of a coefficient list for a polynomial equation, or as a
kevin1990 19:a6d4bdcffb84 389 translation table, depending on what is most appropriate for that sensor.
kevin1990 19:a6d4bdcffb84 390
kevin1990 19:a6d4bdcffb84 391 Translation tables can be expressed in a number of formats, such as 1- or
kevin1990 19:a6d4bdcffb84 392 2-Dimensional tables, with equally- or non-equally-spaced vectors. 2-D tables
kevin1990 19:a6d4bdcffb84 393 are used where the sensor output is affected by both the sensor input and
kevin1990 19:a6d4bdcffb84 394 another factor such as the operating temperature of the sensor itself. If the
kevin1990 19:a6d4bdcffb84 395 sensor output values can be captured for an equally-spaced set of input values
kevin1990 19:a6d4bdcffb84 396 (i.e. values separated by a constant increment, such as 3,6,9,12,etc.), the
kevin1990 19:a6d4bdcffb84 397 equally-spaced table formats allow for a more compact represenation as only the
kevin1990 19:a6d4bdcffb84 398 ouput values need to be listed individually.
kevin1990 19:a6d4bdcffb84 399
kevin1990 19:a6d4bdcffb84 400 Multiple coefficient lists can be specified for a given sensor type, along with
kevin1990 19:a6d4bdcffb84 401 an applicable range of input values, as it may be necessary to apply different
kevin1990 19:a6d4bdcffb84 402 equations depending on the input range. For example, RTD sensors feature a
kevin1990 19:a6d4bdcffb84 403 different linearity curve for input ranges above/below 0 degrees Celsius.
kevin1990 19:a6d4bdcffb84 404
kevin1990 19:a6d4bdcffb84 405 The ADI Sense 1000 allows a flexible look-up table (LUT) data structure up to a
kevin1990 19:a6d4bdcffb84 406 [maximum size](@ref ADI_SENSE_LUT_MAX_SIZE) to be loaded by the user for use
kevin1990 19:a6d4bdcffb84 407 with custom "L2" sensor types. The LUT data structure format, defined as @ref
kevin1990 19:a6d4bdcffb84 408 ADI_SENSE_1000_LUT, allows for a variable set of tables of different formats
kevin1990 19:a6d4bdcffb84 409 to be included as part of the overall data structure. Each table is preceeded
kevin1990 19:a6d4bdcffb84 410 by a descriptor which specifies the format of the following table. A single
kevin1990 19:a6d4bdcffb84 411 top-level header at the start of the LUT specifies how many tables are contained
kevin1990 19:a6d4bdcffb84 412 within. The LUT structure basically looks like this:
kevin1990 19:a6d4bdcffb84 413
kevin1990 19:a6d4bdcffb84 414 |---------------------|
kevin1990 19:a6d4bdcffb84 415 | top-level header |
kevin1990 19:a6d4bdcffb84 416 |---------------------|
kevin1990 19:a6d4bdcffb84 417 | table #0 descriptor |
kevin1990 19:a6d4bdcffb84 418 | table #0 data |
kevin1990 19:a6d4bdcffb84 419 |---------------------|
kevin1990 19:a6d4bdcffb84 420 | table #1 descriptor |
kevin1990 19:a6d4bdcffb84 421 | table #1 data |
kevin1990 19:a6d4bdcffb84 422 |---------------------|
kevin1990 19:a6d4bdcffb84 423 ~~~
kevin1990 19:a6d4bdcffb84 424 |---------------------|
kevin1990 19:a6d4bdcffb84 425 | table #N descriptor |
kevin1990 19:a6d4bdcffb84 426 | table #N data |
kevin1990 19:a6d4bdcffb84 427 |---------------------|
kevin1990 19:a6d4bdcffb84 428
kevin1990 19:a6d4bdcffb84 429 To cater for this flexibility, the data structure definition is inherently
kevin1990 19:a6d4bdcffb84 430 complex. To absorb some of this complexity, a supplementary API function named
kevin1990 19:a6d4bdcffb84 431 @ref adi_sense_1000_AssembleLutData is provided. By providing a list of
kevin1990 19:a6d4bdcffb84 432 pointers to descriptors and data elements for each table to be included in the
kevin1990 19:a6d4bdcffb84 433 LUT structure, along with buffer of allocated memory, this function constructs
kevin1990 19:a6d4bdcffb84 434 the top-level header and appends each table and also fills some fields within
kevin1990 19:a6d4bdcffb84 435 the table descriptors (e.g. length, CRC). Please refer to the "user_lut_data"
kevin1990 19:a6d4bdcffb84 436 application example for an illustration of how this function can be used.
kevin1990 19:a6d4bdcffb84 437