Wrong color camera and slow LTDC

Chuev.Vladimir · ‎2015-09-10

Posted on September 10, 2015 at 14:06

Excuse my English, I am using Google translator.

I use STM32F7. I have two problems.

1) The colors of the camera are not displayed correctly, here are some photos of my problem:

[[this link/image has been flagged as malicious by our security scan software and has been deleted]]

2) The display is updated slowly.

But the picture is displayed quickly if it is one, and there is a delay:

// ------ fast

displayPosL1(320, 240, 0, 0);

Camera_SnapshotStart();

HAL_Delay(200);

displayBackgroundL1((uint32_t)&cameraImage);

// ------

// ------ slowly:

displayPosL1(320, 240, 0, 0);

Camera_SnapshotStart();

HAL_Delay(100);

displayBackgroundL1((uint32_t)&cameraImage);

// ------

// slowly:

while(1){

displayPosL1(320, 240, 0, 0);

Camera_SnapshotStart();

HAL_Delay(100);

displayBackgroundL1((uint32_t)&cameraImage); // Quickly the first time only

HAL_Delay(1000);

// ------

};

// ------

Videos:

fast -

https://youtu.be/sHMj33K9PFE

slowly -

https://youtu.be/20vrmiVyM-M

#ltdc #stm32f7 #cacamera #ov7670

waclawek.jan · ‎2015-09-10

Posted on September 10, 2015 at 22:05

1) The colors of the camera are not displayed correctly, here are some photos of my problem:

Well, obviously the pixel format of camera as grabbed by mcu, and of the display controller, don't match... I am not going to guess, what's wrong. You should thoroughly study the available documentation for camera, the camera interface on mcu, and the lcd; and of course you shouldn't rely on some pre-baked software of dubious origin (''library'').

You can also experiment: start with a single color (a piece of red paper, say), trying to match a single channel of the camera (i.e. ''as purely red as possible'', ''as purely green as possible'', ''as purely blue as possible''); change its intensity (change external illumination) and observe changes the obtained picture. If the camera has AGC or automatic color corrections, this may prove an impossible exercise.

> 2) The display is updated slowly.

> But the picture is displayed quickly if it is one, and there is a delay:

Why do you believe it should be faster?

JW

PS. I don't know what is your mother tongue, but there might be helpful fora in your language out there - e.g. if you speak Russian, try caxapa.ru/arm.html

https://youtu.be/20vrmiVyM-M

Chuev.Vladimir · ‎2015-09-10

Posted on September 11, 2015 at 08:57

1) Thanks, I'll try to deal with it

2) I found a solution to the problem, it was the fact that the camera is working at 7fps

On the forums with my tongue no one helps :(