Hi Alexandra , i write bold my question to example:
Transferring Frame Buffers on SPI Display
The STM32G081 evaluation kit has a SPI display. The principle for transferring the rectangles to the display is the same as for the DSI, but some details are different.
First, when a rectangle is drawn, we start a transfer if none is already in progress:
STM32G0HAL.cpp
void STM32G0HAL::flushFrameBuffer(const touchgfx::Rect& rect)
{
HAL::flushFrameBuffer(rect);
frameBufferAllocator->markBlockReadyForTransfer(); here marked
//start transfer if not running already!
if (!LCDManager_IsTransmittingData()) but here maybe not transfered , is this clean?
{
touchgfx::Rect r;
const uint8_t* pixels = frameBufferAllocator->getBlockForTransfer(r);
LCDManager_SendFrameBufferBlockWithPosition((uint8_t*)pixels, r.x, r.y, r.width, r.height);
}
}
The function LCDManager_SendFrameBufferBlockWithPosition starts a SPI transfer to the display using DMA.
The SPI transfer complete handler calls a function when the transfer is complete:
STM32G0HAL.cpp
void HAL_SPI_TxCpltCallback(SPI_HandleTypeDef *hspi) SPI complete dont say what is complete
{
UNUSED(hspi); WTF unused
LCD_CS_HIGH();
isTransmittingData = 0;
//Change to SPI datasize to 8 bit from 16 bit
heval_Spi.Instance->CR2 &= ~(SPI_DATASIZE_16BIT - SPI_DATASIZE_8BIT);
//signal transfer complete
LCDManager_TransferComplete(); here marked as complete rect send but this maybe isnt true, you need send commands to display then data
}
The LCDManager_TransferComplete functions starts a new transfer:
STM32G0HAL.cpp
void LCDManager_TransferComplete() this function is called from where, when only up marked line then is good for big chaos
{
touchgfx::startNewTransfer();
}
void startNewTransfer()
{
FrameBufferAllocator* fba = HAL::getInstance()->getFrameBufferAllocator();
fba->freeBlockAfterTransfer();
blockIsTransferred = true;
if (fba->hasBlockReadyForTransfer())
{
touchgfx::Rect r; seems as unassigned but ok is assigned as reference in getBlockForTransfer
const uint8_t* pixels = fba->getBlockForTransfer(r);
LCDManager_SendFrameBufferBlockWithPosition((uint8_t*)pixels, r.x, r.y, r.width, r.height);
and this send i see as more important speed function for framebuffering to work, but no one word around this in example
}
}
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Maybe this is clear for you but i see little chaos without info how SPI display work.
For explain full framebuffer for 50Hz framerate need transfer all pixels in max time 1/50s .
No memory or stack heap trouble.
Partial framebuffer seems use ManyBlockAllocator, but too any heap. Why? Next chaos...
