251 lines
10 KiB
C
251 lines
10 KiB
C
/*
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ChibiOS/GFX - Copyright (C) 2012
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Joel Bodenmann aka Tectu <joel@unormal.org>
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This file is part of ChibiOS/GFX.
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ChibiOS/GFX is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/GFX is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file include/gadc/gadc.h
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* @brief GADC - Periodic ADC subsystem header file.
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*
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* @addtogroup GADC
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*
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* @details The reason why ChibiOS/GFX has it's own ADC abstraction is because
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* the Chibi-OS drivers are very CPU specific and do not
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* provide a way across all hardware platforms to create periodic
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* ADC conversions. There are also issues with devices with different
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* characteristics or periodic requirements on the same ADC
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* device (but different channels). This layer attempts to solve these
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* problems to provide a architecture neutral API. It also provides extra
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* features such as multi-buffer chaining for high speed ADC sources.
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* It provides one high speed virtual ADC device (eg a microphone) and
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* numerous low speed (less than 100Hz) virtual ADC devices (eg dials,
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* temperature sensors etc). The high speed device has timer based polling
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* to ensure exact conversion periods and a buffer management system.
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* The low speed devices are assumed to be non-critical timing devices
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* and do not have any buffer management.
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* Note that while only one high speed device has been provided it can
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* be used to read multiple physical ADC channels on the one physical
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* ADC device.
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* All callback routines are thread based unlike the Chibi-OS interrupt based
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* routines.
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*
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* @{
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*/
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#ifndef _GADC_H
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#define _GADC_H
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#include "gfx.h"
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#if GFX_USE_GADC || defined(__DOXYGEN__)
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/* Include the driver defines */
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#include "gadc_lld_config.h"
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/*===========================================================================*/
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/* Type definitions */
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/*===========================================================================*/
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// Event types for GADC
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#define GEVENT_ADC (GEVENT_GADC_FIRST+0)
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/**
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* @brief The High Speed ADC event structure.
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* @{
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*/
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typedef struct GEventADC_t {
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/**
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* @brief The type of this event (GEVENT_ADC)
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*/
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GEventType type;
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/**
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* @brief The event flags
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*/
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uint16_t flags;
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/**
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* @brief The event flag values.
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* @{
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*/
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#define GADC_HSADC_LOSTEVENT 0x0001 /**< @brief The last GEVENT_HSDADC event was lost */
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/** @} */
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/**
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* @brief The number of conversions in the buffer
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*/
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size_t count;
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/**
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* @brief The buffer containing the conversion samples
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*/
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adcsample_t *buffer;
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} GEventADC;
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/**
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* @brief A callback function (executed in a thread context)
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*/
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typedef void (*GADCCallbackFunction)(adcsample_t *buffer, void *param);
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/*===========================================================================*/
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/* External declarations. */
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/*===========================================================================*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Initialise the high speed ADC.
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* @details Initialises but does not start the conversions.
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*
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* @param[in] physdev A value passed to describe which physical ADC devices/channels to use.
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* @param[in] frequency The frequency to create ADC conversions
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* @param[in] buffer The static buffer to put the ADC samples into.
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* @param[in] bufcount The total number of conversions that will fit in the buffer.
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* @param[in] countPerEvent The number of conversions to do before returning an event.
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*
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* @note If the high speed ADC is running it will be stopped.
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* @note Due to a bug in Chibi-OS countPerEvent must be even. If bufcount is not
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* evenly divisable by countPerEvent, the remainder must also be even.
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* @note The physdev parameter may be used to turn on more than one ADC channel.
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* Each channel is then interleaved into the provided buffer. Note 'bufcount'
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* and 'countPerEvent' parameters describe the number of conversions not the
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* number of samples.
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* As an example, if physdev turns on 2 devices then the buffer contains
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* alternate device samples and the buffer must contain 2 * bufcount samples.
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* The exact meaning of physdev is hardware dependent.
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* @note The buffer is circular. When the end of the buffer is reached it will start
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* putting data into the beginning of the buffer again.
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* @note The event listener must process the event (and the data in it) before the
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* next event occurs. If not, the following event will be lost.
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* @note If bufcount is evenly divisable by countPerEvent, then every event will return
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* countPerEvent conversions. If bufcount is not evenly divisable, it will return
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* a block of samples containing less than countPerEvent samples when it reaches the
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* end of the buffer.
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* @note While the high speed ADC is running, low speed conversions can only occur at
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* the frequency of the high speed events. Thus if high speed events are
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* being created at 50Hz (eg countPerEvent = 100, frequency = 5kHz) then the maximum
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* frequency for low speed conversions is likely to be 50Hz (although it might be
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* 100Hz on some hardware).
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*
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* @api
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*/
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void gadcHighSpeedInit(uint32_t physdev, uint32_t frequency, adcsample_t *buffer, size_t bufcount, size_t samplesPerEvent);
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#if GFX_USE_GEVENT || defined(__DOXYGEN__)
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/**
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* @brief Turn on sending results to the GEVENT sub-system.
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* @details Returns a GSourceHandle to listen for GEVENT_ADC events.
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*
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* @note The high speed ADC will not use the GEVENT system unless this is
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* called first. This saves processing time if the application does
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* not want to use the GEVENT sub-system for the high speed ADC.
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* Once turned on it cannot be turned off.
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* @note The high speed ADC is capable of signalling via this method and a binary semaphore
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* at the same time.
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*
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* @api
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*/
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GSourceHandle gadcHighSpeedGetSource(void);
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#endif
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/**
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* @brief Allow retrieving of results from the high speed ADC using a Binary Semaphore and a static event buffer.
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*
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* @param[in] pbsem The binary semaphore is signaled when data is available.
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* @param[in] pEvent The static event buffer to place the result information.
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*
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* @note Passing a NULL for pbsem or pEvent will turn off signalling via this method.
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* @note The high speed ADC is capable of signalling via this method and the GEVENT
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* sub-system at the same time.
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*
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* @api
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*/
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void gadcHighSpeedSetBSem(BinarySemaphore *pbsem, GEventADC *pEvent);
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/**
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* @brief Start the high speed ADC conversions.
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* @pre It must have been initialised first with @p gadcHighSpeedInit()
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*
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* @api
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*/
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GSourceHandle gadcHighSpeedStart(void);
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/**
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* @brief Stop the high speed ADC conversions.
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*
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* @api
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*/
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void gadcHighSpeedStop(void);
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/**
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* @brief Perform a single low speed ADC conversion
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* @details Blocks until the conversion is complete
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* @pre This should not be called from within a GTimer callback as this routine
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* blocks until the conversion is ready.
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*
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* @param[in] physdev A value passed to describe which physical ADC devices/channels to use.
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* @param[in] buffer The static buffer to put the ADC samples into.
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*
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* @note This may take a while to complete if the high speed ADC is running as the
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* conversion is interleaved with the high speed ADC conversions on a buffer
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* completion.
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* @note The result buffer must be large enough to store one sample per device
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* described by the 'physdev' parameter.
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* @note If calling this routine would exceed @p GADC_MAX_LOWSPEED_DEVICES simultaneous low
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* speed devices, the routine will wait for an available slot to complete the
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* conversion.
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* @note Specifying more than one device in physdev is possible but discouraged as the
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* calculations to ensure the high speed ADC correctness will be incorrect. Symptoms
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* from over-running the high speed ADC include high speed samples being lost.
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*
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* @api
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*/
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void gadcLowSpeedGet(uint32_t physdev, adcsample_t *buffer);
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/**
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* @brief Perform a low speed ADC conversion with callback (in a thread context)
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* @details Returns FALSE if there are no free low speed ADC slots. See @p GADC_MAX_LOWSPEED_DEVICES for details.
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*
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* @param[in] physdev A value passed to describe which physical ADC devices/channels to use.
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* @param[in] buffer The static buffer to put the ADC samples into.
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* @param[in] fn The callback function to call when the conversion is complete.
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* @param[in] param A parameter to pass to the callback function.
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*
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* @note This may be safely called from within a GTimer callback.
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* @note The callback may take a while to occur if the high speed ADC is running as the
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* conversion is interleaved with the high speed ADC conversions on a buffer
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* completion.
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* @note The result buffer must be large enough to store one sample per device
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* described by the 'physdev' parameter.
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* @note As this routine uses a low speed ADC, it asserts if you try to run more than @p GADC_MAX_LOWSPEED_DEVICES
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* at the same time.
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* @note Specifying more than one device in physdev is possible but discouraged as the
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* calculations to ensure the high speed ADC correctness will be incorrect. Symptoms
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* from over-running the high speed ADC include high speed samples being lost.
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*
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* @api
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*/
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bool gadcLowSpeedStart(uint32_t physdev, adcsample_t *buffer, GADCCallbackFunction fn, void *param);
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#ifdef __cplusplus
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}
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#endif
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#endif /* GFX_USE_GADC */
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#endif /* _GADC_H */
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/** @} */
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