142 lines
6.6 KiB
Plaintext
142 lines
6.6 KiB
Plaintext
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/*
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ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/**
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* @defgroup ADC ADC Driver
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* @brief Generic ADC Driver.
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* @details This module implements a generic ADC (Analog to Digital Converter)
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* driver supporting a variety of buffer and conversion modes.
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* @pre In order to use the ADC driver the @p HAL_USE_ADC option
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* must be enabled in @p halconf.h.
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*
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* @section adc_1 Driver State Machine
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* The driver implements a state machine internally, not all the driver
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* functionalities can be used in any moment, any transition not explicitly
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* shown in the following diagram has to be considered an error and shall
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* be captured by an assertion (if enabled).
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* @if LATEX_PDF
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* @dot
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digraph example {
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rankdir="LR";
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size="5, 7";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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stop [label="ADC_STOP\nLow Power"];
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uninit [label="ADC_UNINIT", style="bold"];
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ready [label="ADC_READY\nClock Enabled"];
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active [label="ADC_ACTIVE\nConverting"];
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error [label="ADC_ERROR\nError"];
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complete [label="ADC_COMPLETE\nComplete"];
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uninit -> stop [label="\n adcInit()", constraint=false];
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stop -> ready [label="\nadcStart()"];
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ready -> ready [label="\nadcStart()\nadcStopConversion()"];
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ready -> stop [label="\nadcStop()"];
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stop -> stop [label="\nadcStop()"];
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ready -> active [label="\nadcStartConversion() (async)\nadcConvert() (sync)"];
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active -> ready [label="\nadcStopConversion()\nsync return"];
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active -> active [label="\nasync callback (half buffer, circular)\nasync callback (full buffer)\n>acg_endcb<"];
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active -> complete [label="\n\nasync callback (full buffer)\n>end_cb<"];
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active -> error [label="\n\nasync callback (error)\n>error_cb<"];
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complete -> active [label="\nadcStartConversionI()\nthen\ncallback return"];
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complete -> ready [label="\ncallback return"];
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error -> active [label="\nadcStartConversionI()\nthen\ncallback return"];
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error -> ready [label="\ncallback return"];
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}
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* @enddot
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* @else
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* @dot
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digraph example {
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rankdir="LR";
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node [shape=circle, fontname=Helvetica, fontsize=8, fixedsize="true", width="0.9", height="0.9"];
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edge [fontname=Helvetica, fontsize=8];
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stop [label="ADC_STOP\nLow Power"];
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uninit [label="ADC_UNINIT", style="bold"];
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ready [label="ADC_READY\nClock Enabled"];
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active [label="ADC_ACTIVE\nConverting"];
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error [label="ADC_ERROR\nError"];
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complete [label="ADC_COMPLETE\nComplete"];
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uninit -> stop [label="\n adcInit()", constraint=false];
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stop -> ready [label="\nadcStart()"];
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ready -> ready [label="\nadcStart()\nadcStopConversion()"];
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ready -> stop [label="\nadcStop()"];
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stop -> stop [label="\nadcStop()"];
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ready -> active [label="\nadcStartConversion() (async)\nadcConvert() (sync)"];
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active -> ready [label="\nadcStopConversion()\nsync return"];
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active -> active [label="\nasync callback (half buffer, circular)\nasync callback (full buffer)\n>acg_endcb<"];
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active -> complete [label="\n\nasync callback (full buffer)\n>end_cb<"];
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active -> error [label="\n\nasync callback (error)\n>error_cb<"];
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complete -> active [label="\nadcStartConversionI()\nthen\ncallback return"];
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complete -> ready [label="\ncallback return"];
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error -> active [label="\nadcStartConversionI()\nthen\ncallback return"];
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error -> ready [label="\ncallback return"];
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}
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* @enddot
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* @endif
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*
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* @section adc_2 ADC Operations
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* The ADC driver is quite complex, an explanation of the terminology and of
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* the operational details follows.
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*
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* @subsection adc_2_1 ADC Conversion Groups
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* The @p ADCConversionGroup is the objects that specifies a physical
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* conversion operation. This structure contains some standard fields and
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* several implementation-dependent fields.<br>
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* The standard fields define the CG mode, the number of channels belonging
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* to the CG and the optional callbacks.<br>
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* The implementation-dependent fields specify the physical ADC operation
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* mode, the analog channels belonging to the group and any other
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* implementation-specific setting. Usually the extra fields just mirror
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* the physical ADC registers, please refer to the vendor's MCU Reference
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* Manual for details about the available settings. Details are also available
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* into the documentation of the ADC low level drivers and in the various
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* sample applications.
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*
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* @subsection adc_2_2 ADC Conversion Modes
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* The driver supports several conversion modes:
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* - <b>One Shot</b>, the driver performs a single group conversion then stops.
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* - <b>Linear Buffer</b>, the driver performs a series of group conversions
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* then stops. This mode is like a one shot conversion repeated N times,
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* the buffer pointer increases after each conversion. The buffer is
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* organized as an S(CG)*N samples matrix, when S(CG) is the conversion
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* group size (number of channels) and N is the buffer depth (number of
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* repeated conversions).
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* - <b>Circular Buffer</b>, much like the linear mode but the operation does
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* not stop when the buffer is filled, it is automatically restarted
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* with the buffer pointer wrapping back to the buffer base.
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* .
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* @subsection adc_2_3 ADC Callbacks
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* The driver is able to invoke callbacks during the conversion process. A
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* callback is invoked when the operation has been completed or, in circular
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* mode, when the buffer has been filled and the operation is restarted. In
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* circular mode a callback is also invoked when the buffer is half filled.<br>
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* The "half filled" and "filled" callbacks in circular mode allow to
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* implement "streaming processing" of the sampled data, while the driver is
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* busy filling one half of the buffer the application can process the
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* other half, this allows for continuous interleaved operations.
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*
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* The driver is not thread safe for performance reasons, if you need to access
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* the ADC bus from multiple threads then use the @p adcAcquireBus() and
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* @p adcReleaseBus() APIs in order to gain exclusive access.
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*
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* @ingroup HAL_NORMAL_DRIVERS
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*/
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