Mindboards

muntoo wrote:

milluzaj wrote: I learned the screen has a refresh rate of about 50 ms. You might need a wait to display some of the stuff at higher speeds.

timpattinson wrote:10 FPS, hardware limitation.

Has anyone actually tested that? You could try using NeXTScreen at 50ms poll rate with AVI capture, and see how many frames you can see of the line growing:

Code: Select all

//#define POINT

task main()
{
    for(int x = 0; x < 100; x += 5)
    {
#ifdef POINT
        PointOut(x, 32, 1);
#else
        LineOut(0, 32, x, 32, 1);
#endif
        Wait(50);
    }
}

timpattinson wrote:Have now.
2nd latest test release:
With #define commented out:


With #define:


AVI File(with no #define):

nxt_000.zip

(126.86 KiB) Downloaded 283 times

AVI File: (with #define)

nxt_000_2_000.zip

(102.92 KiB) Downloaded 313 times

Jason J Railton wrote:What you’re doing in code is transferring screen data over a serial link to the single-frame buffer held on the LCD driver chip. You’re not controlling the display’s pixels directly. The LCD controller then refreshes the physical screen from that buffer at a rate of around 60Hz or 70Hz. It doesn’t matter how quickly you actually dump data over the serial link, the display only gets refreshed at the rate dictated by the LCD controller.

That’s why small matrix ‘passive’ LCD devices (like calculators, the original Nintendo Game Boy, and the Grapevine PDA on my desk) only have two shades of grey. They flick between two images as fast as possible, but are able to control the delay between refreshes slightly so that one of the frames lasts a little longer than the other, and you get two different shades of grey. They can’t regulate the brightness of individual pixels like more recent ‘active’ colour LCD displays do (TFTs have a discrete transistor for each pixel). [1]

Dick Swan wrote:This is also the place to change the frame rate from 76 to 95 as was mentioned in one of the other posts. [2]

muntoo wrote:They flick between two images as fast as possible, but are able to control the delay between refreshes slightly so that one of the frames lasts a little longer than the other, and you get two different shades of grey.

aswin0 wrote:This means that, in theory, we could make a grayscale display for the NXT!