/**
  @page DAC_GenerateWaveform_TriggerHW_Init DAC example
  
  @verbatim
  ******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
  * @file    Examples_LL/DAC/DAC_GenerateWaveform_TriggerHW_Init/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the DAC_GenerateWaveform_TriggerHW_Init example.
  ******************************************************************************
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. 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.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, 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.
  *
  ******************************************************************************
  @endverbatim

@par Example Description
This example describes how to use the DAC peripheral to generate
a waveform voltage from digital data stream transfered by DMA; 
This example is based on the STM32F2xx DAC LL API; 
peripheral initialization done using LL initialization function
to demonstrate LL init usage.

Example configuration:
One DAC channel (DAC1 channel1) is configured to connect DAC channel output on GPIO pin
to get the samples from DMA transfer and to get conversion trigger from timer.

Other peripherals configured in this example:
one DMA channel and one timer are configured to provide samples to be generated
by DAC peripheral:
sinus waveform, frequency 1kHz, amplitude Vdda.
(these settings can be customized by changing the defined values for the waveform generation parameters in main.c file).

Example execution:
From the main program execution, LED1 is toggling quickly while waiting for
user button press.
DMA and timer are configured and activated to transfer data and trig DAC conversion.
Then, the DAC is configured and activated: waveform is generated on DAC output
indefinitely.
DAC channel output value is provided by DMA transfer, a new value is loaded
at each trigger from trimer.
Finally, LED1 is turned-on.

LED1 is toggling slowly when error is detected.

Connection needed:
None. 
Oscilloscope for monitoring DAC channel output (cf pin below).
Other peripheral used:
  1 GPIO for push button
  1 GPIO for DAC channel output PA.04 (Board Nucleo144: morpho connector CN11 pin 32 (in front of Arduino connector CN9 pin A2), Zio connector CN7 pin 17)
  For waveform voltage generation: 1 DMA channel, 1 timer.

@par Keywords

Analog, DAC, Waveform, Voltage output, Oscilloscope, Signal, Hardware trigger, DMA, Timer, Sinus

@par Directory contents 

  - DAC/DAC_GenerateWaveform_TriggerHW_Init/Inc/stm32f2xx_it.h          Interrupt handlers header file
  - DAC/DAC_GenerateWaveform_TriggerHW_Init/Inc/main.h                  Header for main.c module
  - DAC/DAC_GenerateWaveform_TriggerHW_Init/Inc/stm32_assert.h          Template file to include assert_failed function
  - DAC/DAC_GenerateWaveform_TriggerHW_Init/Src/stm32f2xx_it.c          Interrupt handlers
  - DAC/DAC_GenerateWaveform_TriggerHW_Init/Src/main.c                  Main program
  - DAC/DAC_GenerateWaveform_TriggerHW_Init/Src/system_stm32f2xx.c      STM32F2xx system source file


@par Hardware and Software environment

  - This example runs on STM32F207xx devices.
    
  - This example has been tested with NUCLEO-F207ZG board and can be
    easily tailored to any other supported device and development board.


@par How to use it ? 

In order to make the program work, you must do the following :
 - Open your preferred toolchain
 - Rebuild all files and load your image into target memory
 - Run the example

 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */
