/**
@page DMA2D_BlendingWithAlphaInversion DMA2D blending with alpha inversion example
@verbatim
******************************************************************************
* @file DMA2D/DMA2D_BlendingWithAlphaInversion/readme.txt
* @author MCD Application Team
* @brief Description of the STM32F7xx DMA2D blending with alpha inversion example.
******************************************************************************
* @attention
*
* Copyright (c) 2016 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim
@par Example Description
How to configure the DMA2D peripheral for memory-to-memory operation with
blending transfer and alpha inversion modes.
At the beginning of the main program the HAL_Init() function is called to reset
all the peripherals, initialize the Flash interface and the systick.
Then the SystemClock_Config() function is used to configure the system
clock (SYSCLK) to run at 200 MHz.
In this transfer mode two input sources are fetched : foreground and background.
In this example, the foreground and background are configured as following :
- Foreground object
- input memory address at FLASH memory (static image arrays coded in FLASH).
- Format : RGB565
- Size : 240x130
- Background object
- input memory address at FLASH memory (static image arrays coded in FLASH).
- Format : RGB565
- Size : 240x130
- The constant alpha for foreground is decreased to see the background.
- The alpha mode for foreground and background is configured to see two
superposed images in the resulting image out of the ChromArt DMA2D operation.
- The Foreground alpha inversion is set sequentially to regular then inverted to demonstrate
this new DMA2D feature capability.
The DMA2D blends the two sources pixels buffers stored into the FLASH to compute
the resulting pixel in dedicated output buffer.
The transferred data to the output memory address is the result of the blending operation
between background and foreground (with Foreground alpha inversion set to regular and inverted).
Next step in the pixel pipeline is the use of the LTDC to display the result blending image.
The example acts as follow :
In an infinite while loop
- Use the DMA2D to blend the two sources images.
- If the foreground alpha inversion is disabled (set to DMA2D_REGULAR_ALPHA) :
- Copy the blended image to the LTDC display frame buffer with the following message :
<20>Display Blended Image: Foreground Alpha Inversion OFF<46>
- If the foreground alpha inversion is enabled (set to DMA2D_INVERTED_ALPHA) :
- Copy the blended image to the LTDC display frame buffer with the following message :
<20>Display Blended Image: Foreground Alpha Inversion ON<4F>
- Change the alpha inversion setting, wait for 5 sec and go to the next loop.
As consequence user can see the result blending image with foreground alpha inversion enabled and disabled.
STM32769I-DISCOVERY board's LEDs can be used to monitor the transfer status:
- LED2 is ON when the DMA2D transfer is complete.
- LED1 toggles every when there is a DMA2D transfer error.
- LED1 is ON when there is an error in LTDC transfer/Init process.
@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
@note The application need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@note The STM32F7xx devices can reach a maximum clock frequency of 216MHz but as this example uses SDRAM,
the system clock is limited to 200MHz. Indeed proper functioning of the SDRAM is only guaranteed
at a maximum system clock frequency of 200MHz.
@note The example shows how to use the DMA2D blending with alpha inversion set on the foreground layer.
Nevertheless the same parameter can be applied on the background DMA2D layer depending of the user
application requirements.
@par Keywords
Display, Graphic, DMA2D, LCD, SRAM, ARGB4444, Blending, Alpha Inversion, Memory to memory, Foreground,
Background, RGB565, LTDC, Pixel
@Note<74>If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
<20><><A0><A0><A0>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
<0A><><A0><A0><A0><A0>The address and the size of cacheable buffers (shared between CPU and other masters) must be properly updated to be aligned to cache line size (32 bytes).
@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
<0A><><A0><A0><A0> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
<0A><><A0><A0><A0><A0>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
<0A><><A0><A0><A0><A0>Even though the user must manage the cache coherence for read accesses.
<0A><><A0><A0><A0><A0>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
<0A><><A0><A0><A0><A0>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>
@par Directory contents
- DMA2D/DMA2D_BlendingWithAlphaInversion/Inc/main.h Main configuration file
- DMA2D/DMA2D_BlendingWithAlphaInversion/Inc/stm32f7xx_it.h Interrupt handlers header file
- DMA2D/DMA2D_BlendingWithAlphaInversion/Inc/stm32f7xx_hal_conf.h HAL configuration file
- DMA2D/DMA2D_BlendingWithAlphaInversion/Inc/RGB565_230x170_1.h Image used for DMAD2D validation
- DMA2D/DMA2D_BlendingWithAlphaInversion/Inc/RGB565_230x170_2.h Image used for DMAD2D validation
- DMA2D/DMA2D_BlendingWithAlphaInversion/Src/main.c Main program
- DMA2D/DMA2D_BlendingWithAlphaInversion/Src/stm32f7xx_it.c Interrupt handlers
- DMA2D/DMA2D_BlendingWithAlphaInversion/Src/stm32f7xx_hal_msp.c HAL MSP module
- DMA2D/DMA2D_BlendingWithAlphaInversion/Src/system_stm32f7xx.c STM32F7xx system clock configuration file
@par Hardware and Software environment
- This example runs on STM32F767xx/STM32F769xx/STM32F777xx/STM32F779xx devices.
- This example has been tested with STM32F769I-DISCOVERY 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: Project->Rebuild all
- Load project image: Project->Download and Debug
- Run program: Debug->Go(F5)
*/
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