Display jitters and object skewing

[SAnve]

Hi TouchGFX Team,

  I am currently integrating TouchGFX on STM32F746NE custom board with TFT display of 800x480 resolution . I am using 24bit color depth. Currently facing two issues

1. I see lot of jitters on screen when there is a screen update. I could avoid by increasing VSYNC and Vertical Porch timings. But that resulted in lower refresh rate and caused screen flickering. Is there a way in TouchGFX to use additional buffers to draw and avoid such jitters ?

2. Second issue is object skewing, object appears perfectly fine on TouchGFX designer , but downloaded objects are skewed on y axis. What could be the root cause and How can I avoid this ?

Please let me know

Thanks & Best Regards,

Sanjay

[Martin KJELDSEN]

Hi @SAnve​,

1. Yes, you can use single or double buffering. Please see HAL::setFrameBufferStartAddresses().
2. Please show me some example of this. Sounds like porch setting issue.

/Martin

[SAnve]

Hi Martin,

Thanks for your response.

1. Currently I have enabled double buffering and animation storage

Below are source code lines

hal.setFrameBufferStartAddress((uint16_t*)frameBuf0, bitDepth, true, true);

I had to enable following settings to get rid of jitters on the screen

hal.setFrameRateCompensation(true);

hal.lockDMAToFront Porch(true);

I suspect that before framebuffer update is complete it is used for updating display. Only reducing VSYNC, VBP and VFP values avoids jitters, but it introduces flicker due to reduced refresh rate. Please let me know your input to overcome this issue.

2. Please find attached file, where you can see clock dial is skewed on y-axis.

Thanks & Best Regards,

Sanjay