P1 Video scaling

pic18f2550

Hello,
I would like to modify this driver a little.
The resolution in the memory is 256x192.
The resolution on the monitor is 512x384.
To double the lines is no problem but how do I get the pixel 2x in a row?
Halving the pixel clock is not possible with 35MHz.
Does anyone have a tip?

Ariba

To half the pixelrate, try to change:

                        movi    frqa,#(pr / 5) << 3     'set pixel rate                                      

into

                        movi    frqa,#(pr / 5) << 2     'set pixel rate                                      

or set the PLL to x2 instead of x4

Andy

Edit: You also need to set the pixel based constants like hp, vp, hf, hs, hb to half the value.

Wuerfel_21

Far simpler, no need to change the main video clock, just double up the VSCL value used for the visible area. See documentation for that register.

pic18f2550

vscl_pixel long 1 << 12 + 32 '1 pixel per clock and 32 pixels per set
----->
vscl_pixel long 2 << 12 + 32 '2 pixelclock per pixel and 32 pixels per set

With the correct description, I now also understand this.

'  xtiles = hp / 32              '{Pixelbreite}
  xtiles = hp / 64              '{Pixelbreite}

Wuerfel_21

@pic18f2550 said:

vscl_pixel long 1 << 12 + 32 '1 pixel per clock and 32 pixels per set
----->
vscl_pixel long 2 << 12 + 32 '2 pixelclock per pixel and 32 pixels per set

You actually need to double the 32, too. That indicates the number of video clocks per WAITVID tile. So by setting 2 << 12 + 32, you only actually get the first 16 pixels.

pic18f2550

Ok.
I couldn't recognise this connection in the translated texts.

Thank you.

vscl_pixel long 2 << 12 + 64 '2 pixelclock per pixel and 32 pixels per set