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1768e93710
The default driver type is just an index into a device array defined by the board. If a platform wants to encode additional information in the device type, it can define a custom type. This means we can just set the default type to whatever fits the target CPU best. On ARM this will still be a 32 bit word, but on AVR it will by a 8 bit byte.
138 lines
3.7 KiB
C
138 lines
3.7 KiB
C
/*
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* Copyright (C) 2014 Simon Brummer
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* 2015-2016 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup drivers_periph_dac DAC
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* @ingroup drivers_periph
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* @brief DAC peripheral driver interface
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*
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* Similar to the ADC driver interface (@ref drivers_periph_adc), the DAC
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* interface uses the concept of lines, corresponds to a tuple of a DAC device
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* and a DAC output channel.
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*
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* The DAC interface expects data to be served as a 16-bit unsigned integer,
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* independent of the actual resolution of the hardware device. It is up to the
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* DAC driver, to scale the given value to the maximal width that can be
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* handled. The device driver should, on the other hand, implement the DAC in a
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* way, that it will use the bit width, that comes closest to 16-bit.
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*
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* This kind of 'auto-scaling' is quite sufficient for this interface, as
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* standard DAC peripherals use a fixed conversion resolution internally anyway,
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* so that any particular bit-width configuration on this driver level would not
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* have much effect...
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*
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* # (Low-) Power Implications
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*
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* The configured DAC peripherals are active (and consume power) from the point
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* of initialization. When calling dac_poweroff(), the implementation **should**
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* disable the given DAC line and put the DAC peripheral to sleep (e.g. through
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* peripheral clock gating). When woken up again through dac_poweron(), the
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* given DAC line **should** transparently continue it's previous operation.
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*
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* The DAC driver implementation may need to block (and free) certain power
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* modes in the driver's dac_init(), dac_poweron(), and the dac_poweroff()
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* functions.
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*
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* @{
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* @file
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* @brief DAC peripheral driver interface definition
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*
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* @author Simon Brummer <simon.brummer@haw-hamburg.de>
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*/
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#ifndef PERIPH_DAC_H
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#define PERIPH_DAC_H
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#include <stdint.h>
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#include <limits.h>
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#include "periph_cpu.h"
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#include "periph_conf.h"
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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 Define default DAC type identifier
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*/
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#ifndef HAVE_DAC_T
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typedef uint_fast8_t dac_t;
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#endif
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/**
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* @brief Return codes used by the DAC driver interface
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*/
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enum {
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DAC_OK = 0,
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DAC_NOLINE = -1
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};
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/**
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* @brief Default DAC undefined value
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*/
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#ifndef DAC_UNDEF
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#define DAC_UNDEF (UINT_FAST8_MAX)
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#endif
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/**
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* @brief Default DAC access macro
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*/
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#ifndef DAC_LINE
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#define DAC_LINE(x) (x)
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#endif
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/**
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* @brief Initialize the given DAC line
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*
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* After initialization, the corresponding DAC line is active and its output is
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* set to 0.
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*
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* @param[in] line DAC line to initialize
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*
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* @return DAC_OK on success
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* @return DAC_NOLINE on invalid DAC line
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*/
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int8_t dac_init(dac_t line);
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/**
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* @brief Write a value onto DAC Device on a given Channel
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*
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* The value is always given as 16-bit value and is internally scaled to the
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* actual resolution that the DAC unit provides (e.g. 12-bit). So to get the
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* maximum output voltage, this function has to be called with @p value set to
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* 65535 (UINT16_MAX).
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*
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* @param[in] line DAC line to set
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* @param[in] value value to set @p line to
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*/
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void dac_set(dac_t line, uint16_t value);
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/**
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* @brief Enable the given DAC line
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*
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* @param[in] line DAC line to power on
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*/
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void dac_poweron(dac_t line);
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/**
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* @brief Disable the given DAC line
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*
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* @param[in] line DAC line to power off
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*/
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void dac_poweroff(dac_t line);
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#ifdef __cplusplus
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}
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#endif
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#endif /* PERIPH_DAC_H */
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/** @} */
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